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Dissertations / Theses on the topic 'Molecular rotation'
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1
Bloomquist, Casey. "Detection and characterization of unidirectional molecular rotation." Thesis, University of British Columbia, 2012. http://hdl.handle.net/2429/43141.
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The main goal of this work is the detection of the directionality of molecular rotation and the characterization of two experimental approaches to controlling the directionality of molecular rotation with ultrashort pulses. Control of the directionality of molecular rotation is desired in order to learn more about the internal properties of molecular systems as well as for studying and controlling molecular interactions. Further, the techniques for generating unidirectional molecular rotation must be studied to understand the properties of the molecular ensembles that are generated. In order to detect the directionality of molecular rotation, we use circular polarization sensitive resonance-enhanced multiphoton ionization spectroscopy to allow state-selective directionality detection. In this work we explain this technique and demonstrate its ability to measure the directionality of individual rotational states. The two methods for controlling the directionality of molecular rotation are based on the molecular interaction with either a pair of pulses (a “double-kick” scheme) or a larger sequence of pulses (a “chiral pulse train” scheme). In both cases, rotational control is achieved by varying the polarization of and the time delay between consecutive laser pulses. The double-kick and chiral train methods have demonstrated the ability to control the directionality of molecular rotation but have not been extensively studied. In this work, we perform experiments with both the double-kick and chiral train techniques for thorough comparison and characterization of both methods. We show that both methods produce significant rotational directionality. We also demonstrate that increasing the number of excitation pulses enables one to control the sense of molecular rotation and predominately excite a single rotational state, i.e. quantum state selectivity. To further explore the capabilities of both techniques we perform experiments on selectivity in mixtures of spin isomers and molecular isotoplogues. We demonstrate the ability of both techniques to generate counter-rotation of molecular nuclear spin isomers (here, ortho- and para-nitrogen) and molecular isotopologues.
2
Aston, Georgina Margaret. "Molecular dynamics with muon spin relaxation/rotation." Thesis, University of East Anglia, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.338062.
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Johnson, Mark R. "Molecular rotation and the quantum-classical transition." Thesis, University of Nottingham, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.334785.
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4
Newton, Tony Christopher. "Low temperature rotation in small molecular groups." Thesis, University of Nottingham, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.280102.
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5
Qi, Fei. "Light-driven molecular rotary motors." HKBU Institutional Repository, 2017. https://repository.hkbu.edu.hk/etd_oa/434.
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In the past two decades, a number of artificial molecular motors have been constructed using organic molecules as components which can perform unidirectional motion. Among the best-known examples are the light-activated molecular rotary motors synthesized and analyzed in B. L. Feringa's lab. Yet there is limited understanding of the photoisomerization and thermal isomerization processes that control the speed and energy conversion efficiency of these molecular devices. The present thesis work aims at: 1) developing a computational methodology to provide the atomic and electronic details that allow for quantitative descriptions of light-activated molecular motion, 2) improving the understanding of the physical principles governing photo- and thermal-isomerization processes in specific molecular systems, and 3) proposing a new strategy of molecule design to assist experimental investigations. A key component in our methodology is the calculation of the potential energy surface (PES) spanned by collective atomic coordinates using ab initio quantum mechanical methods. This is done both for the electronic ground state, which is relatively straightforward, and for the photo-excited state, which is more involved. Once the PES is known, classical statistical mechanical methods can be used to analyze the dynamics of the slow variables from which information about the rotational motion can be extracted. Calculation of the PES is computationally expensive if one were to sample the very high dimensional space of the atomic coordinates. A new method, based on the torque experienced by individual atoms, is developed to capture key aspects of the intramolecular relaxation in terms of angular variables associated with the rotational degrees of freedom. The effectiveness of the approach is tested on specific light-driven molecular rotary motors that were successfully synthesized and analyzed in previous experiments. Finally, based on the experience accumulated in this study, a new molecular rotary motor driven by visible light is proposed to reach MHz rotational frequency.
6
Gurusinghe, Ranil Malaka. "Methyl Internal Rotation Probed by Rotational Spectroscopy." Kent State University / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=kent1476282624055414.
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7
Rhee, Won Myung. "A Comprehensive Model for the Rotational Spectra of Propyne CH₃CCH in the Ground and V₁₀=1,2,3,4,5 Vibrational States." Thesis, North Texas State University, 1986. https://digital.library.unt.edu/ark:/67531/metadc332026/.
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The energy states of C₃ᵥ symmetric top polyatomic molecules were studied. Both classical and quantum mechanical methods have been used to introduce the energy states of polyatomic molecules. Also, it is shown that the vibration-rotation spectra of polyatomic molecules in the ground and excited vibrational states can be predicted by group theory. A comprehensive model for predicting rotational frequency components in various v₁₀ vibrational levels of propyne was developed by using perturbation theory and those results were compared with other formulas for C₃ᵥ symmetric top molecules. The v₁₀=1,2,3 and ground rotational spectra of propyne in the frequency range 17-70 GHz have been reassigned by using the derived comprehensive model. The v₁₀=3 and v₁₀=4 rotational spectra of propyne have been investigated in the 70 GHz, and 17 to 52 GHz regions, respectively, and these spectral components assigned using the comprehensive model. Molecular constants for these vibrationally excited states have been determined from more than 100 observed rotational transitions. From these experimentally observed components and a model based upon first principles for C₃ᵥ symmetry molecules, rotational constants have been expressed in a form which enables one to predict rotational components for vibrational levels for propyne up to v₁₀=5. This comprehensive model also appears to be useful in predicting rotational components in more highly excited vibrational levels but data were not available for comparison with the theory. Several techniques of assignment of rotational spectra for each excited vibrational state are discussed. To get good agreement between theory and experiment, an additional term 0.762(J+1) needed to be added to Kℓ=1 states in v₁₀=3. No satisfactory theoretical explanation of this term has been found. Experimentally measured frequencies for rotational components for J→(J+1)=+1 (0≤J≤3) in each vibration v₁₀=n (0≤n≤4) are presented and compared with those calculated using the results of basic perturbation theory. The v₉=2 rotational spectrum of the propyne molecule was introduced in Appendix A to compare the rotational spectra of the same molecule in different vibrational levels v₉ and v₁₀.
8
Korobenko, Aleksey. "Control of molecular rotation with an optical centrifuge." Thesis, University of British Columbia, 2016. http://hdl.handle.net/2429/58640.
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The major purpose of this work is the experimental study of the applicability of an optical centrifuge - a novel tool, utilizing non-resonant broadband laser
radiation to excite molecular rotation - to produce and control molecules
in extremely high rotational states, so called molecular "super rotors", and
to study their optical, magnetic, acoustic, hydrodynamic and quantum mechanical
properties.Science, Faculty of
Physics and Astronomy, Department of
Graduate
9
Debenham, Peter Mark. "Molecular rotation in the quantum and classical regions." Thesis, University of Nottingham, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.284053.
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10
Holland, James K. "High resolution vibration rotation spectrum of fluoroacetylene." Thesis, University of Reading, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.280472.
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Pilizota, Teuta. "A programmable optical angle clamp for rotary molecular motors." Thesis, University of Oxford, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.670185.
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12
Yuan, Peng. "Raman and NMR Investigation of Molecular Reorientation and Internal Rotation in Liquids." Thesis, University of North Texas, 1991. https://digital.library.unt.edu/ark:/67531/metadc278558/.
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Molecular rotational motions are known to influence both Raman scattering of light and nuclear spin relaxation. Therefore, the application of Raman bandshape analysis and NMR relaxation time measurements to probe molecular dynamics in liquids will provide us with a deeper understanding of the dynamical behavior and structure of molecules in the liquid phase. Presented here are (i) studies of molecular reorientation of acetonitrile in the neat liquid phase and in solution by Raman bandshape analysis and NMR relaxation; (ii) studies of reorientational dynamics and internal rotation in transition metal clusters by NMR relaxation.
13
Paso, Risto. "Rotation-vibration spectroscopy of certain symmetric top molecules." Oulu : University of Oulu, 1985. http://catalog.hathitrust.org/api/volumes/oclc/12672901.html.
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14
Ware, John Matthew. "The Rotational Spectra of Propyne in the Ground, V₁₀=1, V₁₀=2, and V₉=1 Vibrational States." Thesis, North Texas State University, 1985. https://digital.library.unt.edu/ark:/67531/metadc332054/.
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The problem of a vibrating-rotating polyatomic molecule is treated, with emphasis given to the case of molecules with C_3v symmetry. It is shown that several of the gross features of the rotational spectra of polyatomic molecules in excited vibrational states can be predicted by group theoretical considerations. Expressions for the rotational transition frequencies of molecules of C_3v symmetry in the ground vibrational state, singly excited degenerate vibrational states, and doubly excited degenerate vibrational states are given. The derivation of these expressions by fourth order perturbation theory as given by Amat, Nielsen, and Tarrago is discussed.
The ground and V_10=1 rotational spectra of propyne have been investigated in the 17 to 70 GHz, and 17 to 53 GHz regions, respectively, and compared with predictions based on higher frequency measurements. The V_9=1 and V_10=2 rotational spectra of propyne have been investigated and assigned for the first time. A perturbation of the V_9=1 rotational spectra for K=-l has been discovered and discussed.
15
Gromova, Olga. "High resolution molecular spectroscopy of the sulfur-containing XY2 type molecules." Dijon, 2010. http://www.theses.fr/2010DIJOS090.
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Dans cette thèse, nous avons effectué des spectres d'absorption à haute résolution de H2S, D2S, HDS et SO2 enregistrés pour la première fois ou avec une meilleure précision expérimentale que les spectres antérieurs. Nous avons développé une méthode originale de "global fitting" qui nous a permis l'analyse de 22 bandes vibrationnelles soit un total de 9700 transitions rovibrationnelles pour la molécule de D2S. Nous avons appliqué cette méthode à des molécules de symétrie CS, en particulier tout le spectre rovibrationnel de la molécule HDS a été analysé. La méthode SPGF est appliquée aux molécules triatomiques H2S, D2S, HDS. Une procédure originale permettant l'identification des bandes très peu intenses a été mise au point pour la première fois et appliquée aux bandes chaudes de la molécule SO2. Le formalisme U(p+1) est adapté aux molécules triatomiques non linéaires de symétrie C2v et les paramètres d'un Hamiltonien vibrationnel sont déterminés dans le cas de la molécule D2SIn this thesis, we analyzed the high resolution absorption molecular spectra of H2S, D2S, HDS and SO2 registered for the first time or with better experimental characteristics as compared with those registered before. For the first time in the practice of rotation-vibrational spectroscopy in the frame of the developed method of "global fitting" the analysis of 22 bands (as a whole more than 9700 rotation-vibrational lines) of D2S molecule is realized. This method of "global fitting" is developed with regard to molecules of Cs symmetry ; on this basis a simultaneous analysis of all the known up to the present rotation-vibrational spectra of HDS molecule is realized. The SPGF method is applied to the three-atom molecules H2S, D2S, HDS. An original procedure of the identification of very weak lines is developed for the first time and practically realized for the example of "hot" lines of SO2 molecule. U(p+1) formalism is adapted to the three-atom non-linear molecules of C2v symmetry and the parameters of a vibrational Hamiltonian is developed in the case of the D2S molecule
16
Lin, Ying. "Progress toward synthetic molecular motors : directed single bond rotation in a prototypical biaryl lactone system /." view abstract or download file of text, 2007. http://proquest.umi.com/pqdweb?did=1324377621&sid=1&Fmt=2&clientId=11238&RQT=309&VName=PQD.
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Thesis (Ph. D.)--University of Oregon, 2007.Typescript. Includes vita and abstract. Includes bibliographical references (leaves 109-124). Also available for download via the World Wide Web; free to University of Oregon users.
17
Hajsaleh, Jamal Y. (Jamal Yousef). "An Experimental Study of Collision Broadening of some Excited Rotational States of the Bending Vibration of Methyl Cyanide." Thesis, University of North Texas, 1993. https://digital.library.unt.edu/ark:/67531/metadc278369/.
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A double modulation microwave spectrometer is used to evaluate the linewidth parameters for some excited rotational components in the bending vibration v_8 of 13CH3 13C 15N and 13CH3C15N isotopomers of methyl cyanide. The linewidth parameters for self-broadening of the ΔJ=2←1 rotational components for the ground v_8 , 1v_8, and the 2v_8 vibrations were determined over a pressure range of 1 to 13 mtorr and at a temperature of 300 K. The double modulation technique is used to explore the high eighth derivative of the line shape profile of the spectral line. This technique proved to give good signal-to-noise ratios and enabled the recovery of weak signals. An experimental method is developed to correct for source modulation broadening. The tests of the ratios of the two inner peak's separation of the eighth derivative of the line showed that they were up to 95% similar to those for a Lorentzian line shape function. The line shapes were assumed to be Lorentzian for the theoretical analysis of the derivative profiles and comparisons were made between experiment and theory on this basis. Dipole moments for vibrationally excited states were calculated from linewidth parameters and show systematic decrease with the increase of excitation. Impact parameters were calculated using the "hard sphere" model of the kinetic theory of gases. The results were many times larger than the size of the molecule itself. This suggests that the dominant interaction is a long range dipole-dipole force interaction.
18
Haviv, Sasson. "CCVJ's fluorescence lifetime as a viscosity measurement tool and its possible application as a tunable picoseconds reference lifetime standard." Diss., Columbia, Mo. : University of Missouri-Columbia, 2007. http://hdl.handle.net/10355/4947.
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Thesis (M.S.)--University of Missouri-Columbia, 2007.The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on November 11, 2008) Includes bibliographical references.
19
Chen, Jen Hui. "Molecular Dynamics and Interactions in Liquids." Thesis, North Texas State University, 1985. https://digital.library.unt.edu/ark:/67531/metadc331452/.
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Various modern spectroscopies have been utilized with considerable success in recent years to probe the dynamics of vibrational and reorientational relaxation of molecules in condensed phases. We have studied the temperature dependence of the polarized and depolarized Raman spectra of various modes in the following dihalomethanes: dibromomethane, dichloromethane, dichloromethane-d2, and bromochloromethane. Among other observed trends, we have found the following: Vibrational dephasing times calculated from the bend) and (C-Br stretch) lineshapes are of the same magnitude in CI^B^. The vibrational dephasing time of [C-D(H) stretch] is twice as long in CD2Cl2 as in CH-^C^, and the relaxation time of (C-Cl stretch) is greater in CI^C^ than in CD2CI2. Isotropic relaxation times for all three stretching vibrations are significantly shorter in C^BrCl than in CI^C^ or CI^B^. Application of the Kubo model revealed that derived modulation times are close to equal for equivalent vibrations in the various dihalomethanes. Thus, the more efficient relaxation of the A^ modes in CE^BrCl can be attributed almost entirely to the broader mean squared frequency perturbation of the vibrations in this molecule.
20
Brydges, Stacey McGlinchey Michael J. "The search for correlated rotation in sterically hindered, multi-n-bladed carbon(n)argon(n)(x+/-) (n = 5, 6 and 7) propellers: from models to molecules /." *McMaster only, 2003.
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21
Dahl, Bartholomew James. "The design and synthesis of prototypical artificial molecular motors : studies of directed bond rotation in chiral biaryls /." view abstract or download file of text, 2007. http://proquest.umi.com/pqdweb?did=1288652831&sid=3&Fmt=2&clientId=11238&RQT=309&VName=PQD.
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Thesis (Ph. D.)--University of Oregon, 2007.Typescript. Includes vita and abstract. Includes bibliographical references (leaves 151-165). Also available for download via the World Wide Web; free to University of Oregon users.
22
Warrington, R. B. "Measurements of parity non-conserving optical rotation in atomic bismuth transitions." Thesis, University of Oxford, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.358699.
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23
Alanko, S. (Seppo). "High resolution infrared spectroscopy on the fundamental bands of 13CH3I." Doctoral thesis, University of Oulu, 1999. http://urn.fi/urn:isbn:9514251857.
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Abstract
This thesis deals with the rotation-vibration theory and high resolution infrared spectroscopy of semirigid C3 molecules. Semirigid molecules form a class of molecules which are strongly bound with one well defined structure, and without low frequency internal motions. The theory, as well as the experimental studies of semirigid molecules are of special importance in the field of rotation-vibration spectroscopy. They provide a good starting point for interpreting and analyzing the spectra of practically all types of molecules.
In this work, the theory is reviewed fromthe standpoint of one particular molecule, 13CH3I, which is a prolate symmetric top with C3 symmetry. The origin and the properties of the rotation-vibration Hamiltonian are discussed in detail. Molecular symmetry plays an important role in these studies. The expansion of the Hamiltonian for nuclear motion in powers of the vibrational operators converges rapidly as numerical examples thoughout the treatment indicate. The molecule is thus a good subject for the perturbation calculations, also reviewed here in detail. 13CH3I can be considered as a model example of semirigid molecules.
From the spectroscopic point of view, this thesis is a study of the six fundamental bands of 13CH3I. The rotational analysis of the vibrational ground state is first given. Special attention is paid to obtaining the axial rotational constants which are problematic for symmetric top molecules. The relatively high energy level density of 13CH3I leads to several resonances. The fundamental bands, especially the higher ones, must therefore be treated as parts of band systems. Care is paid to properly take into account the effects of the near-lying vibrational levels on the constants of the fundamentals. Certain ambiguities in the rotation-vibration Hamiltonian of 13CH3I are also discussed.
24
Russ, Nicholas Joel. "Local Correlation: Implementation and Application to Molecular Response Properties." Diss., Virginia Tech, 2006. http://hdl.handle.net/10919/27004.
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One of the most promising methods for surmounting the high-degree polynomial scaling wall associated with electron correlating wave function methods is the local correlation technique of Pulay and Saebø. They have proposed using a set of localized occupied and virtual orbitals free of the canonical constraint commonly employed in quantum chemistry, resulting in a method that scales linearly (in the asymptotic limit) with molecular size. Pulay and Saeb$oslash; first applied their methods to configuration interaction and later to M$oslash;ller-Plesset perturbation theory. Werner et al. have have extended the local correlation scheme of Pulay and Saeb$oslash; to coupled-cluster theory.
One of the pitfalls of the local correlation methods developed by Pulay and Saeb$oslash; is the dependence of domain selection on the molecular geometry. In other words, as the geometry changes the domain structure of the local correlation calculation can change also, leading to discontinuities in the potential energy surface. We have examined the size of these discontinuities for the homolytic bond cleavage of fluoromethane and the heterolytic bond dissociation of singlet ketene and propadienone.
Properties such as polarizabilities and optical rotation are realized through linear response theory, where the Hamiltonian is subject to an external perturbation and the wave function is allowed to respond to the applied perturbation. Within the context of local correlation it is necessary to understand how the domain structure alters in response to an applied perturbation. We have proposed using solutions to the CPHF equations (coupled-perturbed Hartree-Fock) in order to predict the correlation response to an applied perturbation. We have applied this technique to the calculation of polarizabilities, with very favorable results, and also to optical rotation, with mixed results.Ph. D.
25
Kersell, Heath Ryan. "Investigations on the Complex Rotations of Molecular Nanomachines." Ohio University / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1307126123.
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Jiang, Jun Ph D. Massachusetts Institute of Technology. "Exploring the effect of a potential barrier on the molecular rotation-vibration structure." Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/113971.
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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Chemistry, 2017.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 265-279).
The goal of this thesis is to explore the effect of a potential barrier on the rotation-vibration structure of the sulfur dioxide (SO₂) C̃̃ state and the acetylene (HCCH) Ã state. The minimum-energy geometry of both electronically excited states is qualitatively different from their respective electronic ground state geometry. The SO₂ C state exhibits a barrier (~100 cm-¹) at the C₂u, geometry along the antisymmetric-stretching direction, separating two equivalent minimum-energy configurations with C, geometry. The HCCH A-state potential energy surface (PES) supports both trans- and cis-bent conformers (but not a linear configuration). The trans- and cis-conformer-wells are separated by a barrier of ~5000 cm-¹ (above the trans-bent minimum energy). For both the SO₂ C̃ state and the HCCH Ã-state, the presence of a potential barrier greatly complicates the rotation-vibration structure of the molecule. Interpretation of these barrier-related spectroscopic patterns requires both new experimental observations and new analysis tools, both of which are discussed in this thesis. For the SO₂ C̃ state, an IR-UV double-resonance excitation scheme enables direct observations of levels with odd quanta in the antisymmetric-stretching vibrational mode (v3). A new anharmonic force field is derived for the SO₂ C̃ state, which allows accurate determination of the shape of the barrier on the C̃-state PES. In addition, we develop tools, based on perturbation theory, the polyad model, and semiclassical analysis, to interpret the effect of the barrier on the C̃-state rotation-vibration structure. The cis-trans isomerization in the HCCH Ã-state has been the focus of the Field group acetylene project for the past ten years. However, the diminishing detection efficiency of the laser-induced fluorescence (LIF) scheme (due to acetylene predissociation), combined with a partial breakdown of the polyad fit model, has made it increasingly difficult to understand the HCCH A-state level-structure near the top of the cis-trans isomerization barrier. Two new sensitive and convenient action schemes are reported in this thesis to detect predissociated Ã-state rovibrational levels. The first scheme is based on detection of H-atoms by two-photon laser-induced (3d <-- 1s) fluorescence (3d --> 2p), and the second scheme is based on fluorescence detection of C₂ and C₂H fragments, photolyzed via resonance with the probed Ã-state levels. The photodissciation processes that give rise to the strong photofragment fluorescence signals are also studied in this thesis.
by Jun Jiang.
Ph. D.
27
Al-Share, Mohammad A. (Mohammad Abdel). "Anomalous Behavior in the Rotational Spectra of the v₈=2 and the v₈=3 Vibrations for the ¹³C and ¹⁵N Tagged Isotopes of the CH₃CN Molecule in the Frequency Range 17-95 GHz." Thesis, University of North Texas, 1990. https://digital.library.unt.edu/ark:/67531/metadc330976/.
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The rotational microwave spectra of the three isotopes (^13CH_3^12C^15N, ^12CH_3^13C^15N, and ^13CH_3^13C^15N) of the methyl cyanide molecule in the v_8=3, v_8=2, v_7=1 and v_4=1 vibrational energy levels for the rotational components 1£J£5 (for a range of frequency 17-95 GHz.) were experimentally and theoretically examined. Rotational components in each vibration were measured to determine the mutual interactions in each vibration between any of the vibrational levels investigated.
The method of isotopic substitution was employed for internal tuning of each vibrational level by single and double substitution of ^13C in the two sites of the molecule. It was found that relative frequencies within each vibration with respect to another vibration were shifted in a systematic way. The results given in this work were interpreted on the basis of these energy shifts. Large departure between experimentally measured and theoretically predicted frequency for the quantum sets (J, K=±l, ϑ=±1), Kϑ-l in the v_8=3 vibrational states for the ^13c and ^15N tagged isotopes of CH_3CN showed anomalous behavior which was explained as being due to Fermi resonance. Accidently strong resonances (ASR) were introduced to account for some departures which were not explained by Fermi resonance.
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Niyogi, Sandip. "Synthesis and characterization of molecules to study the conformational barriers of fluorocarbon chains." Thesis, University of North Texas, 2000. https://digital.library.unt.edu/ark:/67531/metadc2511/.
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Fluorocarbons are known to be stiffer than their hydrocarbon analogues, a property that underlines the extensive industrial application of fluorocarbon materials. Although there has been previous studies on the rotational barrier of molecules having fluorocarbon centers, a detailed systematic study is necessary to quantify flurocarbon stiffness. The molecules, Pyrene-(CF2)n-Pyrene, Pyrene-(CF2)n-F, Pyrene-(CH2)n-Pyrene and Pyrene-(CH2)n-H were therefore synthesized to enable the determination of the barrier to rotation of the carbon backbone in fluorocarbons. Conformational studies will be completed with steady-state and time-dependent emission spectroscopy.
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Zhang, Wei. "Computational simulation of biological systems studies on protein folding and protein structure prediction /." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file 2.84Mb, 184 p, 2005. http://wwwlib.umi.com/dissertations/fullcit/3181881.
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Huang, Yue. "Interactions between grain boundary faceting, migration, and grain rotation : color group and molecular dynamics simulation approaches /." Thesis, Connect to this title online; UW restricted, 2006. http://hdl.handle.net/1773/10597.
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Horrom, Travis Scott. "Experimental Generation and Manipulation of Quantum Squeezed Vacuum via Polarization Self-Rotation in Rb Vapor." W&M ScholarWorks, 2013. https://scholarworks.wm.edu/etd/1539623619.
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Nonclassical states of light are of increasing interest due to their applications in the emerging field of quantum information processing and communication. Squeezed light is such a state of the electromagnetic field in which the quantum noise properties are altered compared with those of coherent light. Squeezed light and squeezed vacuum states are potentially useful for quantum information protocols as well as optical measurements, where sensitivities can be limited by quantum noise. We experimentally study a source of squeezed vacuum resulting from the interaction of near-resonant light with both cold and hot Rb atoms via the nonlinear polarization self-rotation effect (PSR). We investigate the optimal conditions for noise reduction in the resulting squeezed states, reaching quadrature squeezing levels of up to 2.6 dB below shot noise, as well as observing noise reduction for a broad range of detection frequencies, from tens of kHz to several MHz. We use this source of squeezed vacuum at 795 nm to further study the noise properties of these states and how they are affected by resonant atomic interactions. This includes the use of a squeezed light probe to give a quantum enhancement to an optical magnetometer, as well as studying the propagation of squeezed vacuum in an atomic medium under conditions of electromagnetically induced transparency (EIT). We also investigate the propagation of pulses of quantum squeezed light through a dispersive atomic medium, where we examine the possibilities for quantum noise signals traveling at subluminal and superluminal velocities. The interaction of squeezed light with resonant atomic vapors finds various potential applications in both quantum measurements and continuous variable quantum memories.
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Hedström, Lucas. "Classifying the rotation of bacteria using neural networks." Thesis, Umeå universitet, Institutionen för fysik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-160518.
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Bacteria can quickly spread throughout the human body, making certain diseases hard or impossible to cure. In order to understand how the bacteria can initiate and develop into an infection, microfluidic chambers in a lab environment are used as a template of how bacteria reacts to different types of flows. However, accurately tracking the movement of bacteria is a difficult task, where small objects has to be captured with a high resolution and digitally analysed with computationally heavy methods. Popular imaging methods utilise digital holographic microscopy, where three-dimensional movement is captured in two-dimensional images by numerical reconstruction of the diffraction of light. Since numerical reconstructions become computationally heavy when a good accuracy is required, this master's thesis work focus on evaluating the possibility of using convolutional neural networks to quickly and accurately determine the spatial properties of bacteria. By thorough testing and analysis of state of the art and old networks a new network design is presented, designed to eliminate as many imaging issues as possible. We found that there are certain network design choices that help with reducing the overall error of the system, and with a well chosen training set with sensible augmentations, some networks were able to reach a 60% classification accuracy when determining the vertical rotation of the bacteria. Unfortunately, due to the lack of experimental data where the ground-truth is known, not much experimental testing could be performed. However, a few tests showed that images of high quality could be classified within the expected range of vertical rotation.Bakterier kan snabbt sprida sig genom människokroppen, vilket försvårar starkt möjligheterna att kurera vissa sjukdomar. För att få en inblick i hur bakterier kan initiera och utvecklas till en infektion används som mall laborativa uppställningar med vätskekanaler i mikroskala när man söker förstå hur bakterier reagerar på olika typer av flöden. Att spåra dessa rörelser med god säkerhet är dock en utmaning, då man experimentellt söker fånga små skalor med hög upplösning, som sedan ska analyseras med datorintensiva metoder. Populära avbildningsmetoder använder sig utav digital holografisk mikroskopi, där tredimensionella rörelser kan fångas med hjälp av tvådimensionella bilder genom att numeriskt återskapa ljusets brytningsmönster mot objekten. Eftersom dessa metoder blir beräkningstunga när god säkerhet krävs så utforskar detta examensarbete möjligheterna att utnyttja faltningsnätverk för att snabbt och säkert bestämma vertikalrotationen hos bakterier avbildade med holografi. Genom nogranna tester av moderna samt äldre nätverk så presenteras en ny nätverksdesign, utvecklad i mål med att eliminera så många avbildningsproblem som möjligt. Vi fann att vissa designval vid nätverksutvecklingen kan hjälpa med att reducera klassificeringsfelen givet vårt system, och med en väl utvald träningsmängd med lämpliga justeringar så lyckades vi nå en klassificeringssäkerhet på över 60% med vissa nätverk. På grund av bristande experimentellt data där de riktiga värdena är kända så har ingen utförlig experimentell analys utförts, men några tester på experimentella bilder i god kvalité har visats ge resultat som tyder på en korrekt analys inom den förväntade vertikalrotationen.
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Abney, Joshua. "STUDIES OF MAGNETICALLY INDUCED FARADAY ROTATION BY POLARIZED HELIUM-3 ATOMS." UKnowledge, 2018. https://uknowledge.uky.edu/physastron_etds/57.
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Gyromagnetic Faraday rotation offers a new method to probe limits on properties of simple spin systems such as the possible magnetic moment of asymmetric dark matter or as a polarization monitor for polarized targets. Theoretical calculations predict the expected rotations of linearly polarized light due to the magnetization of spin-1/2 particles are close to or beyond the limit of what can currently be measured experimentally (10−9 rad). So far, this effect has not been verified. Nuclear spin polarized 3He provides an ideal test system due to its simple structure and ability to achieve high nuclear spin polarization via spin-exchange optical pumping (SEOP). To maximize the expected signal from 3He, a SEOP system is built with a modern narrowband pumping laser and a 3He target designed to use with a multipass cavity. Additionally, a sensitive triple modulation apparatus for polarimetry is utilized and further developed to detect Faraday rotations on the order of nanoradians. This works presents the results of the measurement of the magnetic Faraday effect.
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Leitner, Dietmar A. "Dynamic NMR Study of Bond Rotational Activation Parameters in Micelles." PDXScholar, 1992. https://pdxscholar.library.pdx.edu/open_access_etds/4603.
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The behavior of surfactants in solution has been and still is of scientific, technological, and industrial interest. The micelle forming compounds sodium N( octyloxycarbonyl)sarcosinate (NaOcSarc), and sodium N-(decyloxycarbonyl)sarcosinate (NaDecSarc) show in aqueous solution two lH NMR N-methyl peaks arising from a possible cis- or trans-conformation. The relative population of the N-methyl peaks depends mostly on the concentration of surfactant indicating micelle formation. Upon heating the two peaks start to coalesce and finally appear as one single peak . The temperature range in which this phenomenon occurs is from 25°C to 65°C. The primary interest of this study was to determine the activation parameters of rotation about the carbonyl-nitrogen (C-N) bond. Dynamic nuclear magnetic resonance spectroscopy was employed to approach this problem. A complete bandshape analysis was performed in order to calculate the free energy (G++), enthalpy (H++), and entropy (S++) of activation. The effect of a different counter ion (Li+) and sodium chloride salt addition were tested for possible changes of the activation parameters. Studies in nonaqeous solvents were conducted with the free acid form of the mentioned carbarnates. Dimethylsulfoxide and chloroform were chosen as organic solvents for these particular experiments. The critical micellar concentrations of all surfactants were determined, and the assignment of the individual N-methyl peaks to the correspondend conformation could be unambiguously shown by a two dimensional NMR experiment. The cmc's show strong salt dependence. The effect of a lithium as an alternative counter ion has a less drastic effect. Micellization seems not to occur in the free acid cases. Interestingly, the surfactants show stronger salt dependence than micellization dependence upon the activation parameters, indicating that solvent exposure occurs at the C-N partial double bond and considerable deformation of the ideal spherical shape.
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Nelson, Michael R. Jr. "Ab initio molecular orbital studies: Rydberg states of H₄ barriers to internal rotation studies binding of CO₂ to carbonyl groups isoprene and ozone complexes." Diss., Georgia Institute of Technology, 1998. http://hdl.handle.net/1853/30278.
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Chen, Fu-Tseng Andy. "Molecular Dynamics in the Liquid Phase by FT-NMR, FT-IR and Laser Raman Lineshape Analysis." Thesis, University of North Texas, 1988. https://digital.library.unt.edu/ark:/67531/metadc330608/.
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Nuclear magnetic resonance (NMR) provides a convenient probe for the study of molecular reorientation in liquids because nuclear spin-lattice relaxation times are dependent upon the details of molecular motion. The combined application of Raman and Infrared (IR) lineshape analysis can furnish more complete information to characterize the anisotropic rotation of molecules. Presented here are the studies of NMR relaxation times, together with Raman/IR Mneshape analysis of the solvent and temperature dependence of rotational diffusion in 1,3,5-tribromobenzene and 1,3,5-trifluorobenzene. In these experiments, it was found that the rotational diffusion constants calculated from Perrin's stick model were two to three times smaller than the measured values of D, and D,,. Similarly, rotational diffusion constants predicted by the Hu-Zwanzig slip model were too large by a factor of 2. Application of the newer Hynes-Kapral-Weinberg model furnished rotational diffusion constants that were in reasonable agreement with the experimental results. The vibrational peak frequencies and relaxation times of the isotropic Raman spectra of the υ1 modes of CD2Br2 and CHBr3 were studied in solution. The frequency shifts in non-interactive solvents were explained well on the basis of solution variations in the dispersion energy. In Lewis bases, the displacements were in some, but not all, cases greater than predicted. On the other hand, it was found that the vibrational relaxation times of the C-H/C-D modes decreased dramatically in all Lewis base solvents. Therefore, it was concluded that relaxation times of the υ1 modes, rather than frequency shifts, furnish a more reliable measure of hydrogen bonding interactions of halomethanes in solution.
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Pennanen, T. (Teemu). "Computational studies of NMR and magneto-optical rotation parameters in water." Doctoral thesis, University of Oulu, 2012. http://urn.fi/urn:isbn:9789514297311.
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Abstract
In this thesis nuclear magnetic resonance (NMR) and magneto-optical rotation (MOR) parameters are investigated for water, paying special attention to the effect of solvation from gaseous to liquid phase. Nuclear magnetic shielding and quadrupole coupling tensors of NMR spectroscopy are studied for gaseous and liquid water. Liquid state is modelled by a 32-molecule Car-Parrinello molecular dynamics simulation, followed by property calculations for the central molecules in clusters cut out from the simulation trajectory. Gaseous state is similarly represented by a one-molecule simulation. Gas-to-liquid shifts for shielding constants obtained this way are in good agreement with experiments. To get insight into the local environment and its effect on the properties the clusters are divided into groups of distinct local features, namely the number of hydrogen bonds. The analysis shows in detail how the NMR tensors evolve as the environment changes gradually from the gas to liquid upon increasing the number of hydrogen bonds to the molecule of interest. The study sheds light on the usefulness of NMR experiments in investigating the local coordination of liquid water. To go a bit further, the above mentioned NMR parameters along with the spin-spin coupling constant are examined for water dimer in various geometries to have insight into solvation and hydrogen bonding phenomena from bottom to top. Characteristic changes in the properties are monitored as the geometry of the dimer is systematically varied from very close encounter of the monomers to distances and orientations where hydrogen bonding between monomers ceases to exist. No rapid changes during the hydrogen bond breaking are observed indicating that the hydrogen bonding is a continuous phenomenon rather than an on-off situation. However, for analysis purposes we provide an NMR-based hydrogen bond definition, expressed geometrically, based on the behaviour of the NMR properties as a function of dimer geometry. Our definition closely resembles widely used definitions and thus reinforces their validity.
Magneto-optical rotation parameters, the nuclear spin optical rotation (NSOR) and the Verdet constant, are computed for gaseous and liquid water, in the same manner as the NMR properties above. Recent pioneering experiments including NSOR for hydrogen nuclei in liquid water and liquid xenon have demonstrated that this technique has a potential to be a useful new probe of molecular structure. We reproduce computationally, applying a first-principles theory developed recently in the group, the experimental NSOR for hydrogen nuclei in liquid water, and predict hydrogen NSOR in gaseous water along with the oxygen NSOR in liquid and gaseous water. NSOR is an emerging experimental technique that needs interplay between theory and computation for validation, steering and insight.
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Amyay, Badr. "Etude détaillée et modélisation globale du spectre de vibration-rotation de 12C2H2." Doctoral thesis, Universite Libre de Bruxelles, 2012. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/209739.
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Nous avons contribué à l’amélioration du modèle global de 12C2H2. Ce modèle, exploitant la notion de polyade, a pris en compte l’ensemble des données spectrales de vibration-rotation de la littérature concernant des niveaux de vibration jusqu’à 8900 cm-1. Au terme de notre travail, les 18415 raies publiées dans la littérature sont reproduites par le modèle endéans 3 fois leur incertitude expérimentale qui est typiquement de l’ordre voire meilleure que 0,001 cm-1. L’introduction des interactions de type Coriolis, réalisée pour la première fois pour l’acétylène dans une perspective globale aux côtés des interactions de type vibrationnel, s’est révélée déterminante dans la qualité des résultats. La totalité des énergies de vibration-rotation de la molécule a été prédite jusqu’à des énergies de l’ordre du visible et pour des valeurs du nombre quantique de rotation allant jusqu’à 120. Nous avons exploité ces résultats pour calculer de manière exhaustive les intensités spectrales dans les régions importantes pour la détection de 12C2H2 dans les atmosphères stellaires et planétaires, impliquant un calcul des fonctions de partition jusqu’à 2000 K avec une précision inégalée dans la littérature. D’autres paramètres thermodynamiques, énergie de Helmholtz, entropie, enthalpie et capacité calorifique à pression constante ont été calculées dans la foulée, tenant compte des deux isomères de spin de la molécule. Au cours de ce travail, une banque de donnée a été mise sur pied, rassemblant les positions de toutes les raies de vibration-rotation connues de 12C2H2 et impliquant des niveaux de vibration jusqu’à 8900 cm-1. Nous avons alimenté cette banque de données, base du modèle global, en nous focalisant sur l’analyse de trois régions spectrales à partir de nouveaux spectres acquis via des collaborations internationales.
La première région considérée est celle de l’infrarouge lointain, les spectres étant enregistrés par le Dr A. Predoi-Cross utilisant le rayonnement synchrotron de la « Canadian Light Source ». Les niveaux de pliage à basse énergie sont impliqués, entre 0 et 3000 cm-1. Nous avons étudié en particulier la bande de différence v5-v4 située vers 117 cm-1 et les bandes chaudes associées. Un ensemble de 731 nouvelles raies ont été attribuées sur ce spectre. De nouvelles données ont été obtenues sur 12C13CH2 à cette occasion.
La seconde région qui nous a occupé est celle de la première excitation –CH, vers 3300 cm-1. Des spectres d’émission à très haute température (~1455 K) ont été enregistrés par le groupe du Prof. R. Georges à l’université de Rennes. 3811 nouvelles raies ont été attribuées sur ces spectres, les bandes chaudes observées et analysées impliquant jusqu’à 4 quanta d’excitation des modes de pliage et atteignant des niveaux de vibration jusqu’à 6000 cm-1.
La troisième région analysée est celle de la seconde excitation –CH, vers 6700 cm-1, sur base de spectres à très haute résolution enregistrés par le groupe du Dr. A. Campargue à l’université de Grenoble. L’analyse de ces spectres nous a permis d’attribuer 1825 nouvelles raies et, via les bandes chaudes, d’accéder aux niveaux de vibration excités jusqu’à 8900 cm-1.
L’ensemble de ces nouvelles raies a été ajustée simultanément avec les données de la littérature utilisant 396 paramètres effectifs dont la pertinence a été examinée. La déviation standard sans dimension est de 1.07.
Doctorat en Sciences
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Hamraoui, Khalid. "Contrôle quantique de la rotation moléculaire et de processus de Résonance Magnétique Nucléaire." Thesis, Bourgogne Franche-Comté, 2019. http://www.theses.fr/2019UBFCK020/document.
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L’objectif de cette thèse est d’appliquer des méthodes de contrôle quantique pour manipuler la dynamique rotationnelle de molécules et améliorer l’efficacité de processus en résonance magnétique nucléaire.Ces techniques ont été utilisées théoriquement et expérimentalement pour contrôler l’orientation d’une molécule toupie symétrique à l’aide de champ THz. Cette étude a été généralisée à une grande distance d’interaction entre le champ et l’échantillon. Dans ce cas, la molécule ne peut plus être considérée comme isolée. Nous avons également montré jusqu'à quel point l’évolution temporelle du degré d’orientation pouvait être mise en forme. Des méthodes de contrôle optimal ont permis de déterminer le champ THz pour atteindre cet état à la fois à températures nulle et non-nulle. Un autre chapitre présente un nouvel algorithme d’optimisation pour les dynamiques périodiques. Cet algorithme est appliqué à la maximisation du SNR en RMN. Un dernier chapitre est dédié à un article de vulgarisation sur l’effet de la raquette de tennis. Cet effet géométrique peut être observé dans tout corps rigide suffisamment asymétriqueThe goal of this thesis is to apply quantum control techniques to manipulate molecular rotation and to enhance the efficiency of processes in Nuclear Magnetic Resonance.These techniques have been used theoretically and experimentally to control the orientation of a symmetric top molecule by means of THz laser fields. This study has been extended to the case of a long interaction distance between the field and the sample. In this case, the molecule cannot be approximated as isolated. We have also shown the extend to which the time evolution of the degree of orientation can be shaped. Optimal control techniques were used to design the THz field which allows to reach the corresponding dynamics, both at zero and non zero temperatures. Another chapter proposes a new optimization algorithm in the case of periodic quantum dynamics. We apply this algorithm to the maximization of the SNR in NMR. A last chapter is dedicated to a popular paper about the tennis racket effect. This geometric effect can be observed in any asymetric rigid body
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Prost, Emilien. "Optique ultra-rapide dans des rotors moléculaires synchrones." Thesis, Bourgogne Franche-Comté, 2020. http://www.theses.fr/2020UBFCK009.
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Cette thèse porte sur l'étude de la rotation unidirectionnelle de molécules et en particulier de l'effet Doppler rotationnel en génération de troisième harmonique dans des rotors moléculaires synchrones. L'effet Doppler rotationnel apparaît lors de l'interaction entre une onde polarisée circulairement et un objet anisotrope en rotation. Lors de cette interaction, il y a échange de moment angulaire entre l'onde et l'objet induisant, par conservation de l'énergie et du moment angulaire, un décalage en fréquence de l'onde après l'interaction. Une observation du décalage en fréquence de la troisième harmonique générée dans des molécules en mouvement de rotation unidirectionnelle est présentée. Un modèle analytique décrit dans ce manuscrit permet de prévoir quatre décalages en fréquences dépendant du sens des polarisations circulaires fondamentale et harmonique ainsi que du sens de rotation des molécules. Ces quatre décalages en fréquences ont été observés expérimentalement lors de la génération de troisième harmonique dans des molécules de O2, N2 et CO2 en rotation unidirectionnelle. Une étude minutieuse de l'effet Doppler rotationnel et de la physique sous-jacente à ce phénomène a ensuite été conduite. Une analyse de l'état de polarisation de la troisième harmonique produite dans des rotors moléculaires synchrones a également été réalisée permettant de mettre en avant le haut degré d'ellipticité de l'harmonique produite. À partir de cette analyse en polarisation, l'orientation de l'axe moléculaire peut être retrouvée, offrant une méthode de mesure de la fréquence angulaire des molécules en rotationThis thesis reports on the study of unidirectional rotation of molecules and focuses on the rotational Doppler effect occuring in the course of third-harmonic generation in coherently spinning molecules.The rotational Doppler effect appears when a circularly polarized wave interacts with an anisotropic rotating object. During the interaction, an exchange of angular momentum and energy between the field and the object occurs, leading to a frequency shift of the wave. In this work, the frequency shift of the third-harmonic generated in unidirectionaly rotating molecules has been observed. An anlytical model developped in the mansucript forsees four kinds of frequency shifts depending on the mutual handedness of the circular polarization of the fundamental and harmonic fields and the handedness of the rotating molecules. The four shifts have been measured in third-harmonic generation in unidirectionaly rotating molecules of O2, N2, and CO2. A thorough study of the rotational Doppler effect and the underlying physics has been conducted. A polarization analysis of the third-harmonic produced in coherently spinning molecules has also been done, showing the high degree of ellipticty of the harmonic. From this polarization analysis, the orientation of the molecular axis can be retrieved, providing a new way to measure the angular frequency of rotating molecules
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Le, Marquer Nicolas. "Vers la synthèse d'une roue à rochet moléculaire." Thesis, Le Mans, 2015. http://www.theses.fr/2015LEMA1025/document.
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Dans le domaine des machines moléculaires, la recherche d'un système produisant un mouvement orienté fait l'objet d'intenses recherches. Des résultats ont déjà été obtenus en ce sens mais n'exploitant pas le mouvement brownien comme le font les systèmes trouvés dans la nature comme la myosine. Nous proposons donc la synthèse d'une roue à rochet avec pour but de mimer ce phénomène, si besoin avec une activation de faible énergie. La première partie de ce travail a consisté en la conception par modélisation de l'équivalent synthétique d'une roue à rochet, basiquement constituée d'une roue crantée et d'un cliquet en vue d'étudier si une telle molécule pourrait produire une rotation orientée. Ce système est constitué d'un motif bishomoinositol fonctionnalisé en tant que roue et d'un cycloadduit de l'anthracène comme cliquet, liés par des bras espaceurs. La synthèse d'un système modèle dans lequel un motif bicyclo[2.2.2]octane joue le rôle de roue simplifiée a été menée afin de valider les différentes stratégies de synthèse. A cette occasion, une méthode alternative de la synthèse du diacide bicyclo[2.2.2]octanoïque a été mise au point ainsi qu'une méthodologie d'estérification compatible avec cet acide ainsi que le diacide 9,10-anthracènedioïque. Nous sommes ainsi parvenus à obtenir le produit de macrolactonisation, avec de possibles application comme roue de nanovéhicules. La synthèse du modèle a été l'occasion de pointer certaines impossibilités synthétiques au niveau des espaceurs (éthers, amides, triazoles, tétrazoles, alcènes) dans le système original. Un nouveau travail de modélisation a permis d'aboutir à une cible accessible synthétiquement conservant le comportement de roue à rochet. Dans cette optique, la synthèse du bishomoinositol fonctionnalisé par des acides en tête de pont a été entreprise par une première voie incluant ces groupements au départ de la synthèse, une seconde voie introduisant ces groupements en fin de séquenceIn the field of molecular machines, systems producing an oriented motion have been intensely looked for. Results, obtained toward this goal, do not exploit Brownian motion whereas it happens in natural systems such as myosin. Hereby we propose the synthesis of a molecular ratchet aiming to mimic this phenomenon or to be able to act as a molecular motor through low energy activation. The first part of this work consisted in the design by modelisation of a synthetic equivalent of a ratchet, basically consisting of a toothed wheel and a pawl. This study aim at determining if such a molecule could produce an oriented motion by simple Brownian motion. This system is consisting of a functionalized bishomoinositol moiety as the wheel and a cycloadduct of anthracene as the pawl, linked by spacers allowing the adjustment of the energy barriers. The synthesis of a model where a bicyclo[2.2.2]octane moiety plays the role of a simplified wheel has been conducted in order to validate various synthetic strategies. This gave the opportunity to develop an alternative method of the synthesis of the bicyclo[2.2.2]octanedicarboxylic diacid as well as an esterification methodology compatible with the bulkiness or low solubility of both partners. The macrolactonization product could be obtained and opens some possible applications as nanovehicle wheels. The synthesis of the model was the occasion to highlight synthetic limitations concerning the spacers (ethers) in the original system. A new series of targets taking into account the synthetic restrictions while keeping the ratchet behavior were designed. The discovery of another synthetic difficulties (amides, triazoles, tetrazoles and alkenes) yielded a single refined target. Toward this goal, the synthesis of the bishomoinositol functionalized in the bridgehead position was engaged in a first pathway including these functions at the beginning of the synthesis, the second way introducing them on the bishomoinositol at the end of the sequence
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Schmiedt, Hanno [Verfasser], Stephan [Gutachter] Schlemmer, and Per [Gutachter] Jensen. "Molecular symmetry, super-rotation, and semi-classical motion. New ideas for old problems / Hanno Schmiedt ; Gutachter: Stephan Schlemmer, Per Jensen." Köln : Universitäts- und Stadtbibliothek Köln, 2017. http://d-nb.info/1132248299/34.
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Powoski, Robert A. "Molecular Structure Analyses of Asymmetric Hydrocarbon Liquid Compounds in the Gas Phase Using Chirped-pulse Fourier Transform Microwave Spectroscopy: Acyl Chlorides and Perfluorinated Acyl Chlorides." Thesis, University of North Texas, 2011. https://digital.library.unt.edu/ark:/67531/metadc103374/.
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Examinations of the effects of (a.) alkyl carbon chain length and (b.) perfluorination of acyl chlorides; propionyl chloride, butyryl chloride, valeroyl chloride, and perfluorinated acyl chlorides; perfluoropropionyl chloride and perfluorobutyryl chloride, are reported and compared using CP-FTMW spectroscopy. All of these molecules are already published in various journals except for valeroyl chloride. The chapters are organized by molecule alkyl chain length and include some background theory. Conformational stability, internal rotation, helicity, and ionic character of the C-Cl bond via the nuclear electric quadrupole coupling constant (χzz) are analyzed. Results show syn, syn-anti/syn-gauche, and syn-anti-anti/syn-gauche-anti stable conformations. Internal rotation was only seen in propionyl chloride. Helicity was not observed. (χzz) was observed to be inert to alkyl chain length, ~ 60 MHz and ~ 65 MHz for the nonfluorinated and fluorinated acyl chlorides. Partial fluorination and varying functional groups are recommended.
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Robert, Séverine. "Description globale de la structure de vibration-rotation de la molécule d'acétylène." Doctoral thesis, Universite Libre de Bruxelles, 2009. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/210307.
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Afin de progresser dans la compréhension de la structure de vibration-rotation de l'acétylène dans son état électronique fondamental, un modèle global a été développé avec succès pour trois de ses isotopologues, permettant d'attribuer de nouvelles données de spectres enregistrés sous diverses conditions expérimentales. L'ensemble des programmes d'analyse rovibrationnelle globale conçus à l'Université Catholique de Louvain par le Pr. A. Fayt et al. ont été utilisés pour répondre aux demandes de collaborateurs tels que les Prs. A. Campargue, A. Jolly ou encore R. Georges dans le cadre de plusieurs problèmes de type spectroscopique, notamment pour des applications astrophysiques. Le modèle global et son pouvoir prédictif mis ainsi à l'épreuve, nous avons démontré la validité de nos jeux de paramètres pour ces trois molécules.Concernant l'isotopologue principal, $H^{12}C^{12}CH$, 14 nouvelles bandes ont été mises à jour à partir de spectres enregistrés en CRDS à Grenoble par A. Campargue et al. Une analyse rovibrationnelle globale a été effectuée jusqu'à une énergie de 8600 cm$^{-1}$. 10750 raies ont été ajustées simultanément sur les 12137 attribuées dans la littérature. 266 paramètres ont été déterminés par la méthode de moindres-carrés. La déviation standard sans dimension du fit est de 0.92. La bande $u_{5}$-$u_{4}$, centrée vers 117 cm$^{-1}$ a été simulée. La valeur du moment de transition associé, $
Doctorat en Sciences
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Gyawali, Prakash. "Terahertz spectroscopy of molecules and molecular complexes of atmospheric interest exhibiting large amplitude motions." Electronic Thesis or Diss., Université de Lille (2022-....), 2023. http://www.theses.fr/2023ULILR071.
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L'atmosphère est composée d'un large éventail de molécules et d'espèces. Parmi celles-ci, la vapeur d'eau et ses complexes jouent un rôle important dans le phénomène du réchauffement de la planète et du changement climatique. L'analyse spectroscopique de ces complexes est essentielle pour comprendre divers processus atmosphériques. Cependant, les connaissances sur les complexes d'eau à faible liaison dans le domaine des ondes térahertz sont encore limitées en raison de leurs caractéristiques spectrales complexes et des défis expérimentaux. La complexité spectrale résulte souvent des mouvements de grande amplitude limités par de faibles barrières de potentiel.Nous présentons le développement d'un spectromètre d'émission à jet pulsé destiné à l'étude des complexes moléculaires dans la gamme des térahertz. Les développements expérimentaux ont été accompagnés d'une analyse comparative des modèles de mouvements de grande amplitude sur les molécules d'intérêt atmosphérique. Nous avons commencé avec des halogénures d'acétyle présentant un mouvement de torsion périodique du groupe méthyle. Nous avons obtenu des modèles précis des spectres de rotation du chlorure d'acétyle et du bromure d'acétyle avec une précision expérimentale. Nous avons ensuite étudié les spectres de rotation de la méthylamine dans son premier état excité de torsion. La méthylamine est caractérisée par deux mouvements de grande amplitude : la torsion et l'inversion. Le spectre rotationnel de la méthylamine a été analysé à l'aide du modèle dit "hybride" qui, pour la première fois, a permis d'attribuer et de modéliser avec précision les états de torsion excités les plus bas. Enfin, les spectres rotationnels à haute résolution du complexe à faible liaison ammoniac-eau ont été mesurés à l'aide du nouveau spectromètre. Pour l'analyse du complexe l'ammoniac-eau qui présente deux mouvements de grande amplitude similaires à ceux de la méthylamine, nous avons également appliqué l'approche "hybride" démontrant ainsi son avantage dans l'application aux états excités et aux cas à faible barrière.Mots clés: spectroscopie d'ondes mm/sub-mm, mouvements de grande amplitude, haute résolution, rotation interne, complexe faiblement lié, impulsion de jet, impulsion chirpéeThe atmosphere comprises a diverse array of molecules and species. Among these, water vapor and its complexes have a significant role in the phenomenon of global warming and climate change. Spectroscopic analysis of such complexes is essential for understanding various atmospheric processes. However, there is still a limited knowledge on weakly bounded water complexes in the terahertz wave range due to their complex spectral features and experimental challenges. Spectral complexity often results from the large amplitude motions limited by low potential barriers.We present the development of pulsed-jet emission spectrometer intended for studies of molecular complexes in the terahertz range. Experimental developments were accompanied by benchmarking large amplitude motions models on the molecules of atmospheric interest. We started with acetyl halides exhibiting a periodic torsional motion of methyl group. We obtained accurate models of the rotational spectra of acetyl chloride and acetyl bromide within experimental accuracy. Subsequently, the rotational spectra of methylamine in its first excited torsional state were studied. Methylamine is characterized by two large amplitude motions: torsion and inversion. The rotational spectrum of methylamine was analyzed using the so-called "hybrid" model that for the first time allowed accurate assignment and modeling of the lowest excited torsional states. Finally, the high-resolution rotational spectra of ammonia-water weakly bounded complex were measured using the newly built spectrometer. For the analysis of ammonia-water which exhibits two large amplitude motions similar to methylamine, we also applied the "hybrid" approach demonstrating thus its advantage in the application to excited states and low barrier cases.Keywords: mm/sub-mm wave spectroscopy, large-amplitude motions, high-resolution, internal rotation, weakly bounded complex, pulse jet, chirped pulse
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Akbari, Saeed. "Morphology and Dynamics of Catenanes in Dilute Solutions and at Liquid/Liquid Interface." University of Akron / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=akron1544538754254472.
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Anis, Fatima. "Role of nuclear rotation in H[subscript]2[superscript]+ dissociation by ultra short laser pulses." Diss., Manhattan, Kan. : Kansas State University, 2009. http://hdl.handle.net/2097/2181.
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Zheng, Chao Durig James R. "Conformational stability from temperature-dependent infrared spectra of noble gas solutions, normal coordinate analyses, adjusted r₀ structural parameters and barrier to internal rotation of some substituted amine, hydrazine and three-membered ring compounds." Diss., UMK access, 2006.
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Thesis (Ph. D.)--Dept. of Chemistry and Dept. of Physics. University of Missouri--Kansas City, 2006."A dissertation in chemistry and physics." Advisor: James R. Durig. Typescript. Vita. Description based on contents viewed Jan. 29, 2007; title from "catalog record" of the print edition. Includes bibliographical references (leaves 447-460). Online version of the print edition.
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Bournazel, Manon. "Dynamique collisionnelle sondée par alignement moléculaire post-impulsionnel." Electronic Thesis or Diss., Bourgogne Franche-Comté, 2024. http://www.theses.fr/2024UBFCK011.
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Au cours de ces trente dernières années, le développement des sources laser ultra courtes a permis d'accélérer la recherche sur le contrôle des mouvements de rotation des molécules par alignement moléculaire. En régime post-impulsionnel, lorsque la durée de l'impulsion laser est plus courte que la période rotationnelle de la molécule, une récurrence périodique de transitoires d'alignement se manifeste suite à l'excitation laser. Ces molécules, en interaction avec leur environnement, subissent des collisions internes qui atténuent l'amplitude de ces transitoires au cours du temps. L'étude de la disparition de cet alignement moléculaire en fonction du temps ou de la pression permet d'extraire des informations sur la relaxation des cohérences et des populations rotationnelles.Dans cette thèse nous nous intéressons à la dynamique collisionnelle de différents systèmes sondés via l'alignement moléculaire ou les échos rotationnels. Nous observons dans un premier temps des effets non séculaires et non markoviens dans le domaine temporel aux temps courts. Les échos rotationnels sont ensuite utilisés pour améliorer l'alignement de la molécule d'acétone très asymétrique et donc difficile à aligner. Enfin, pour s'affranchir de la dépendance de l'amplitude des échos par rapport au délai entre les deux impulsions laser et l'éclairement de la deuxième impulsion, nous mettons en place une nouvelle technique associant un modulateur spatial de lumière à un algorithme d'évolution pour créer une bi-impulsion dont les paramètres optimaux sont automatiquement ajustés afin de garder une amplitude d'écho constanteOver the past thirty years, the development of ultra-short laser sources has accelerated the research on the control of molecular rotational motions by molecular alignment. For field free molecular alignment, when the pulse duration of the laser is shorter than the rotationnal period of the molecule, a periodic reccurence of revivals follows the excitation by the laser pulse. These molecules, interacting with their environment, undergo internal collisions that attenuate the amplitude of these revivals over time. Studying the disappearance of this molecular alignment over time or pressure provides insights into the relaxation of coherences and rotational populations.In this thesis, we investigate the collisional dynamics of various systems, probed through molecular alignment or rotational echoes. First we observe nonsecular and non-Markovian effects in the temporal domain at short timescales. Rotationnal echoes are then used to improve the alignment of acetone which is highly asymmetric and hence challenging to align. In addition, to overcome the dependence of echo amplitude on the delay between the two laser pulses and the intensity of the second pulse, we introduce a new technique involving a spatial light modulator and a learning algorithm to create a bi-pulse. The optimal parameters of the bi-pulse are automatically adjusted to maintain the echo amplitude constant
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Lin, Yuan. "Numerical modeling of dielectrophoresis." Licentiate thesis, Stockholm, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4014.
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