Dissertations / Theses: 'Atomic/Molecular Structure and Spectra'

1

Sochi, T. "Atomic and molecular aspects of astronomical spectra." Thesis, University College London (University of London), 2012. http://discovery.ucl.ac.uk/1369696/.

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In the first section of this thesis, we present the atomic part of our investigation. A C2+ atomic target was prepared and used to generate theoretical data required in the investigation of recombination lines that arise from collisions between electrons and ions in thin plasma found in planetary nebulae and other astrophysical objects. The R-matrix method of electron scattering theory was used to describe the C2+ plus electron system. Theoretical data concerning bound and autoionizing states were generated in the intermediate-coupling approximation by R-matrix and Autostructure codes and compared to experimental data. The comparison revealed very good agreement. These theoretical data were then used to generate dielectronic recombination data for C+ which include transition lines, oscillator strengths, radiative transition probabilities, as well as emissivity and dielectronic recombination coefficients. The data were cast in the form of a line list, called SS1, containing 6187 optically-allowed transitions which include many C II lines observed in astronomical spectra. The data were validated by comparison to C+ recombination data obtained from a number of sources in the literature. This line list was used to analyze the spectra from a number of astronomical objects, mainly planetary nebulae, and identify their electron temperature where the observational data were obtained from the literature. The electron temperature investigation was also extended to include free electron energy analysis which uses observational and theoretical data of FF and FB transitions to investigate the long-standing problem of discrepancy between the results of recombination and forbidden lines analysis and its possible connection to the electron distribution (Maxwellian or non-Maxwellian). In the course of this investigation two elaborate methods, one for finding and analyzing resonances (K-matrix method) and the other for analyzing and identifying electron temperature from astronomical spectra (least squares minimization), were employed. A computer program for atomic transition analysis was also developed and used as the main tool for obtaining the line list and analyzing the observational spectra. In the second section of the thesis we present the results of our molecular investigation; the generation of a comprehensive, calculated line list of frequencies and transition probabilities for the singly deuterated isotopologue of H3+, H2D+. The line list, which is the most comprehensive one of its kind in existence, contains over 22 million rotational-vibrational transitions occurring between more than 33 thousand energy levels and covers frequencies up to 18500 cm-1. All energy levels with rotational quantum number, J, up to 20 are considered, making the line list useful for temperatures up to at least 3000 K. About 15% of these levels are fully assigned with approximate rotational and vibrational quantum numbers. The list is calculated using a previously proposed, highly accurate, ab initio model implemented in a high-accuracy computer code based on a two-stage discrete variable representation (DVR) approach. Various consistency checks were carried out to test and validate the results. All these checks confirmed the accuracy of the list. A temperature-dependent partition function, valid over a more extended temperature range than those previously published, and cooling function are presented. Temperature-dependent synthetic spectra for the temperatures T=100, 500, 1000 and 2000 K in the frequency range 0-10000 cm-1 were also generated and presented graphically.

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2

Harris, M. "Collisional effects in atomic spectra." Thesis, University of Newcastle Upon Tyne, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.352727.

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3

McHugh, D. R. "Collisional and radiative studies in atomic spectra." Thesis, University of Newcastle Upon Tyne, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.376224.

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4

Shannon, I. "Collisional and radiative effects in atomic spectra." Thesis, University of Newcastle Upon Tyne, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.371770.

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5

Blundell, S. "The theory of nuclear effects in atomic spectra." Thesis, University of Oxford, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.355731.

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6

Sanchez-FortuÌn, Stoker Jamie. "Theoretical studies of line mixing in atomic and molecular spectra." Thesis, University of Newcastle Upon Tyne, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.399087.

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7

Shaw, John A. "Photoabsorption spectra of hydrogen in magnetic fields." W&M ScholarWorks, 1993. https://scholarworks.wm.edu/etd/1539623837.

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Measurements of the absorption spectrum of atomic H in strong magnetic fields have been analyzed. The measurements, performed by the Bielefeld, Germany experimental group, investigated the photoabsorption to levels near the ionization threshold in magnetic fields ranging from 2.7 to 6 Tesla. Taking advantage of a classical scaling law, the photon energy and the magnetic field strength were varied simultaneously in the experiment and the absorption rate vs. B{dollar}\sp{lcub}-1/3{rcub}{dollar} at fixed scaled-energy, {dollar}\varepsilon{dollar} = E/(B/B{dollar}\sb{lcub}\rm o{rcub})\sp{lcub}2/3{rcub}{dollar} was measured. The absorption rate was observed to exhibit sinusoidal fluctuations which we correlate with closed classical orbit of the electron. A Fourier transformation of this signal yields peaks which we interpret as "recurrence strengths" which depend upon the classical action of the closed orbit. Closed-orbit theory gives formulas for these recurrence strengths. as the scaled energy is increased, observed recurrences proliferate, consistent with the change from orderly to chaotic motion of the electron. Bifurcation theory provides organizing principles for understanding this proliferation and for interpreting the data. New "exotic" orbits suddenly appear "out of nowhere" through saddle-node bifurcations. The "main sequence" of orbits is produced from an orbit parallel to B through a sequence of pitchfork and period-doubling bifurcations. Other recurrences are created by period-tripling and higher-order bifurcations of existing orbits. These bifurcations can have generic structure, or sometimes the structures are modified by symmetries of the system. Focusing effects associated with these bifurcations cause some recurrences to be particularly strong.

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8

Hughes, Alan Nigel. "The structure and spectra of molecular ions." Thesis, University of Newcastle upon Tyne, 2013. http://hdl.handle.net/10443/2217.

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I give a review of the theory of the hydrogen molecular ion H2+ and its isotopomers D2+ and HD+ including the direct analytical solution and the standard adiabatic approximation. I discuss dissociation limits for homonuclear and heteronuclear species; the effect of an external electric field; non adiabatic calculations, relativistic and radiative effects; and spectroscopic measurements of H2+ and D2+ with a comparison of theoretical to experimental values. I give a detailed description of the fast ion-beam spectrometer as used for both laser-beam and microwave spectroscopy and describe the challenges involved in making high resolution spectroscopic measurements. An account is given of theory, experimental details and measurements of transition frequencies and intensities of the forbidden rotational transition (v = 19, N = 1) - (v = 19, N = 0) in the ground electronic state (X2Σg+, also represented as 1sσg) of H2+. Theory has predicted that the transition has measurable intensity due to the Fermi contact hyperfine interaction causing a breaking of electronic g/u symmetry resulting in the mixing of ortho-para states. The measurements were made in both single and double resonance using a fast ion beam/microwave spectrometer at a transition frequency of 14961.7 ± 1.1 MHz, in agreement with the theoretical prediction of 14960 ± 3 MHz. An account is also given of a further search that was conducted for a second forbidden rotational transition (v = 0, N = 1) - (v = 0, N = 0) in the first excited electronic state (2pσu) of H2+. A discussion is given on the possibility of making further observations of forbidden rotational transitions and the experimental difficulties involved; and of adapting the experimental techniques used in order to observe the recently discovered (v = 1, N = 0) in the first excited electronic state (2pσu) of H2+.

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9

Batchelor, D. R. "Auger electron spectra from bulk elements." Thesis, University of Sussex, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.373904.

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Zahidi, Assou. "Etudes structurales et dynamiques de complexes macrocycliques par rmn heteronucleaire." Université Louis Pasteur (Strasbourg) (1971-2008), 1986. http://www.theses.fr/1986STR13171.

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Etude de la complexation de cations et d'anions par des ligands synthetiques a l'aide de la rmn heteronucleaire (**(6)li, **(7)li, **(13)c, **(14)n, **(15)n, **(19)f, **(31)p, **(35)cl et **(109)ag) et de mesures d'effet overhauser homo- et heteronuclaires

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11

Darlison, A. G. "Multi-mode effects in Jahn-Teller absorption spectra." Thesis, University of Oxford, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.370246.

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Lobb, William S. "Collision studies in the spectra of alkali metals." Thesis, University of Newcastle Upon Tyne, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.328148.

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13

Gao, Jing. "Photoabsorption spectra of hydrogen and alkali atoms in electric fields." W&M ScholarWorks, 1994. https://scholarworks.wm.edu/etd/1539623858.

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A systematic study of the photoabsorption spectra of highly excited hydrogen and alkali atoms in electric fields is presented, based on the semiclassical closed-orbit theory. In most respects, hydrogen and alkali atoms behave similarly, because the excited alkali atoms have a single electron outside of a small ionic core, and the core only produces small shifts of energy levels and small phase shifts of scattered wave functions.;For hydrogen, the classical motion of the excited electron is regular and closed orbits can be enumerated. Above the zero-field ionization threshold, the system is rather simple. There is only one closed orbit, called the parallel orbit, which goes out from the Coulomb center along the electric field and later returns to the center. This orbit is unstable. Nevertheless, the orbit and its repetitions produce recurrences in time, that lead to oscillations in the absorption spectrum. Comparisons between theory and experiments show good agreement.;Below threshold, the parallel orbit becomes stable and, as the energy decreases, many other orbits bifurcate out of it. These closed orbits form orderly patterns, and the associated recurrences are most clear if the absorption spectrum is measured using a scaled-variables method and its Fourier transform, the recurrence spectrum, is computed. Bifurcations are readily observable in such spectra because they create new recurrences, and because at a bifurcation, observed recurrences are especially strong. We predicted the sequence of bifurcations, and the energies at which each would occur, in a paper published early in 1994. Recently, experimental measurements carried out at M.I.T. have confirmed these predictions.;Near a bifurcation, the original form of closed-orbit theory diverges, since a bifurcation is correlated with a focus of classical orbits. An improved closed-orbit theory is derived by using the uniform semiclassical approximation, and by extending the wave function from the real three dimensional space into a four dimensional space. In this extended space, the orbits of the electron near the nucleus are straight lines. These lines are arranged so that they form a cusped caustic, and furthermore they form cylindrical foci in two independent planes in the four-dimensional space. We derive a formula for the wave function associated with this cylindrically focused cusp, and make a new prediction of the behavior of the recurrence spectrum near a bifurcation. These predictions are compared with new experimental results. We find that the improved form of closed orbit theory accurately accounts for experimental measurements both globally and locally.

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14

Huang, Yuanyuan. "Effects of molecular motion on deuteron magic angle spinning NMR spectra." W&M ScholarWorks, 2007. https://scholarworks.wm.edu/etd/1539623519.

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Solid state deuteron NMR experiments, especially magic angle spinning (MAS) and off-magic angle spinning (OMAS), are developed to explore dynamical systems. A theoretical discussion of interactions relevant for spin-1 nuclei is presented. Practical aspects of MAS/OMAS experiments are described an detail. The dominant quadrupolar coupling interaction in deuteron NMR has been simulated and the effects of multiple-frame molecular motions on MAS/OMAS spectra are taken into account in this calculation. Effects of chemical shift anisotropy are also simulated, and shown to be small under conditions of rapid sample spinning.;Two numerical methods, direct integration and an efficient simulation routine based on Floquet thoery, are discussed. Improvements in computational efficiency of the Floquet method in computing solid stae deuteron MAS/OMAS spectrum makes the quantitative analysis of molecular motion possible: complex multiple frame molecular motions, deuteron quadrupolar interactions and chemical shift anisotropy are now included in a single simulation routine and the effects of the multiple-frame molecular motions can be analyzed by comparing the line shapes of simulations with those of experiments.;The enhanced motional sensitivity of deuteron NMR MAS/OMAS makes it possible to detect temperature-dependent motion rates of urea molecules in octanoic acid/urea inclusion compounds. Temperature-dependent deuteron OMAS line shapes have been recorded and fitted through least-square procedures, to provide rates of rotation about both CN and CO bonds. Activation energies have been calculated for these motions. The power and utility of OMAS is demonstrated by this investigation.;The phenyl ring motions in appropriately labeled L-phenylalanine and N-acetyl-L-phenylalanine methyl ester/cyclodextrin inclusion compound have also been studied through high field deuteron MAS experiments. Phenylalanine MAS spectra with ultra-fast ring-flip motion have been simulated and the range of phenyl ring flip rates is obtained by comparing the simulated and experimental spectra. In the studies of phenylalanine/cyclodextrin inclusion compound, an approach to a physically reasonable diffusion model has also been made by increasing the number of jump sites per unit solid angle included in the calculation. These simulations involve repeated diagonalization of very large matrices and demonstrate the capability of the approach to handle complex dynamical systems.

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15

Goodwin, E. J. "An investigation of the rotational spectra of weakly bound complexes." Thesis, University of Exeter, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.373819.

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16

Stephenson, Ernest Hope. "A study of molecular spectra of small molecules in excited vibrational states." Thesis, Bangor University, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.296175.

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17

Dinh, Thi Hanh Physics Faculty of Science UNSW. "Application of many-body theory methods to atomic problems." Publisher:University of New South Wales. Physics, 2009. http://handle.unsw.edu.au/1959.4/43734.

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There is strong interest in atomic and nuclear physics to the study of superheavy elements by the search for the island of stability in the region Z=104 to Z=126. There are many experimental efforts and theoretical works devoted to these study in measuring the spectra and chemical properties. In this thesis, calculations of the spectra and the hyperfine structure of some superheavy elements have been performed in an attempt to enrich our knowledge about the elements and even may help in their detection. We perform the high-precision relativistic calculations to determine the spectra of the superheavy element Z=119 (eka-Fr) and the singly-ionized superheavy element Z=120+ (eka-Ra+). Dominating correlation corrections beyond relativistic Hartree-Fock are included to all orders in the residual electron interaction using the Feynman diagram technique and the correlation potential method. The Breit interaction and quantum electrodynamics radiative corrections are considered. Also, the volume isotope shift is determined. We present the relativistic calculations for the energy levels of the superheavy element Z=120. The relativistic Hartree-Fock and configuration interaction techniques are employed. The correlations between core and valence electrons are treated by means of the correlation potential method and many-body perturbation theory. We also try to address the absence of experimental data on the electron structure and energy spectrum of the Uub element (Z=112) by calculating its energy levels. The relativistic Hartree-Fock and configuration interaction methods are combined with the many-body perturbation theory to construct the many-electron wave function for valence electrons and to include core-valence correlations. The hyperfine structure constants of the lowest s and p1/2 states of superheavy elements Z=119 and Z= 120+ are calculated. Core polarization, dominating correlation, Breit and quantum electrodynamic effects are considered. The dependence of the hyperfine structure constants on nuclear radius is discussed. Measurements of the hyperfine structure combined with our calculations will allow one to study nuclear properties and distribution of magnetic moment inside nucleus. Finally, we discuss the possibility of measuring nuclear anapole moments in atomic Zeeman transitions and perform the necessary calculations. Advantages of using Zeeman transitions include variable transition frequencies and the possibility of enhancement of parity nonconservation effects.

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18

Webb, S. W. "Temperature and pressure induced changes in gas phase rotational Raman spectra." Thesis, University of Bradford, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.374938.

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19

Jolma, Kalevi. "High resolution far infrared spectra of certain light linear three and four atomic molecules." Oulu : University of Oulu, 1985. http://catalog.hathitrust.org/api/volumes/oclc/15465428.html.

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20

Chakravarty, Charusita. "Open shell van der Waals complexes : spectra and dynamics of Ar-OH." Thesis, University of Cambridge, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.358606.

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21

Du, Meng Li. "The effect of closed classical orbits on quantum spectra: Ionization of atoms in a magnetic field." W&M ScholarWorks, 1987. https://scholarworks.wm.edu/etd/1539623773.

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A quantitative theory of oscillatory spectra for atoms in a magnetic field is developed. When an atom is placed in a magnetic field, and absorption spectrum into states close to the ionization threshold is measured, it is found that the absorption as a function of energy is a superposition of many sinusoidal oscillations. Such interesting and surprising phenomenon are fully explained and described by the theory.;The theory is based on three approximations: (1) Near the atomic nucleus, the diamagnetic field is negligible. (2) Far from the nucleus, the wave propagates semiclassically. (3) Waves returning to the nucleus are similar to (cylindrically-modified) Coulomb-Scattering waves. Using these approximations, together with the simple physical picture of absorption process, formula is derived for the transition rate as a function of final states energy.;The main result is that the transition rate is equal to the sum of two very different kinds of contributions. The first is the averaged transition rate in the absence of the magnetic field, which is a smooth function of energy; the second is itself a sum over many oscillations. Each oscillation is closely associated with a band of wave, initially going out from the nucleus, propagating along a family of trajectories, and finally returning to the vicinity of the nucleus. Because in the center of the family of trajectories is a closed orbit going from the nucleus and returning to the nucleus, we say "a closed orbit makes an oscillatory contribution to the absorption spectrum".;Formulas and algorithms are derived and specified for the calculations of the spectrum from the initial quantum state, dipole polarization, and the properties of the closed classical orbits. Good agreements with experiments were found. Very detailed interpretations are obtained.

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22

Critchley, Andrew Duncan James. "Structure of free radicals." Thesis, University of Newcastle Upon Tyne, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.327188.

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23

James, Jessica. "Nuclear structure effects in atomic parity non-conservation." Thesis, University of Oxford, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.259953.

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Firth, N. C. "Molecular beam reactive scattering of fluorine atoms." Thesis, University of Manchester, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.377732.

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25

Salvi, Anna Maria. "The relationship between atomic number and the intensity of the energy loss structure of the photoelectron spectrum." Thesis, University of Surrey, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.320908.

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26

Shiell, Ralph C. "Experimental investigations of doubly charged atomic and molecular species." Thesis, University of Newcastle Upon Tyne, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.294869.

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27

Makrides, Constantinos. "Quantum Theory of Atomic and Molecular Structures and Interactions." University of Toledo / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1404484126.

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28

Choi, Ji Il. "Applications of nonlinear dynamics in atomic and molecular systems." Diss., Available online, Georgia Institute of Technology, 2007:, 2007. http://smartech.gatech.edu/bitstream/1853/16207/1/choi_jiil_200708_phd.pdf.

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Thesis (Ph. D.)--Physics, Georgia Institute of Technology, 2008.
Turgay Uzer, Committee Chair ; M. Raymond Flannery, Committee Member ; Chandra Raman, Committee Member ; Dragomir Davidovic, Committee Member ; Chongchun Zeng, Committee Member.

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29

Stone, P. J. "The electronic structure of actinyl ions." Thesis, University of Oxford, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.371576.

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30

Roney, Alfred B. "Structure and dynamics of heterogeneous molecular systems." [Tampa, Fla] : University of South Florida, 2006. http://purl.fcla.edu/usf/dc/et/SFE0001678.

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31

Hayashi, Shinsuke. "Theoretical study of electronic structure and spectroscopy of molecules containing metallic atoms." Phd thesis, Université Paris-Est, 2008. http://tel.archives-ouvertes.fr/tel-00462184.

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In this work we have investigated the electronic properties of several types of molecular systems involving a metallic element. Our motivation for such applications on metallic compounds was to obtain an accurate description of close lying electronic states, in which the relativistic effects of heavy atoms are known to be important. Thus various approaches and methods have been employed to treat these effects, including the multi-configurational method, with atomic pseudopotentials and large basis sets. In the first study, we have determined the properties of the low lying electronic states of the diatomic compounds MX, whose combinations in the solid phase produce ionic semi-conductor materials with piezoelectric properties. Based on highly correlated ab initio calculations, we have elucidated the common properties of the low lying electronic states of these diatomic compounds with eight valence electrons, which can be considered as precursors for piezoelectric effects in their solid phase. Based on our electronic structure calculations, we could identify among these diatomic compounds those who could lead to good candidates for piezoelectric effects. As the second application, we have determined the electronic structure and the spectroscopic constants for the ground state of the HZnF molecule and for the low lying electronic states of its diatomic fragments. This application was initiated and motivated by interesting and puzzling results on the close system HZnCl. Comforted by our experience with the previous studies, we used the pseudopotentials approach to obtain an accurate description of the low lying states of ZnH which could be satisfactorily compared with existing data. Next, the ZnF and ZnCl diatomic molecules have been studied with the same ansatz to reveal the properties of so far unknown electronic states. Finally, the potential energy surface of the ground state of HZnF has been determined, and several spectroscopic properties have been deduced

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32

Griffin, Christine D. "Breit-Pauli Atomic Structure Calculations for Si III." DigitalCommons@Robert W. Woodruff Library, Atlanta University Center, 2016. http://digitalcommons.auctr.edu/cauetds/51.

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Theoretical study of energy levels, oscillator strengths, transition probabilities, and lifetimes of Si III lines has been reported in this thesis. These atomic parameters are required for the interpretation of emission and absorption lines of Si III and for the modeling of astrophysical plasmas including Galactic High Velocity Clouds (HVCs), the Sun, and white dwarf stars. We used Hartree-Fock (HF) and Multiconfiguration Hartree-Fock (MCHF) methods in our calculations. We have considered 58 levels of the 3s2, 3s3p, 3p2, 3s3d, 3s4s, 3s4p, 3s4d, 3s4f, 3s5s, 3s5p, 3s5d, 3s6s, and 3s5f configurations. The relativistic corrections are included in Breit-Pauli approximation by using one-body Darwin, mass correction, spin-orbit operators, and two-body spin-other-orbit and spin-spin operators. The results have been compared with previous theoretical results and available experimental data, and generally a good agreement is found.

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Kalpaxis, P. "Theoretical investigation of the structure of fluids." Thesis, University of Kent, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.304996.

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Whitfield, Melinda D. "Doppler-Broadening of Light Nuclei Gamma-Ray Spectra." TopSCHOLAR®, 2010. http://digitalcommons.wku.edu/theses/1075.

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Non-destructive methods of material interrogation are used to locate hidden explosives and thwart terrorism attempts. In one such method materials are bombarded with neutrons which react with the nuclei of the atoms within causing a de-excitation process emitting a gamma-ray. The spectrum displayed by the collection of these gamma-rays gives valuable information regarding the material’s elemental make-up. It has been hypothesized that gamma-rays from neutron-induced gamma-ray reactions on light elements with atomic numbers less than 20, including most of the gamma-rays of interest in explosives detection, are Doppler-broadened. This thesis focuses on the gamma ray spectra from the 4438 keV gamma ray in the 12C (n, n’γ) reaction wherein Doppler broadening was investigated. A graphite sample was exposed to 14 MeV neutrons and the 12C gamma ray spectra collected using an HPGe detector positioned at four different angles with respect to the neutron beam; near 00, 450, 900 and 1350. No other experimental parameter was changed. The resultant gamma ray spectra indicated Doppler broadening had occurred.

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Wu, Tao. "Structure-function analysis of vascular tethering molecules using atomic force microscope." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/31844.

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Thesis (Ph.D)--Mechanical Engineering, Georgia Institute of Technology, 2009.
Committee Chair: Zhu, Cheng; Committee Member: Barry, Bridgette; Committee Member: Boyan, Barbara; Committee Member: McEver, Rodger; Committee Member: McIntire, Larry. Part of the SMARTech Electronic Thesis and Dissertation Collection.

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Talukder, Md Mesbah Uddin. "Analysis of the structure and molecular interactions of seipin, using atomic force microscopy." Thesis, University of Cambridge, 2015. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.709137.

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Galek, Peter Tadeusz A. "Atomic and molecular electronic structure and quantum chemical calculations with quantum Monte Carlo." Thesis, University of Cambridge, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.614146.

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Lee, John Jethro. "Photoemission-monitored x-ray standing wave studies of molecular adsorbate surface structure." Thesis, University of Warwick, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.272660.

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Wang, Yongqian. "Nanometer characterization of quantum compound semiconductor heterostructures grown by molecular beam epitaxy." Diss., Georgia Institute of Technology, 2002. http://hdl.handle.net/1853/20192.

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40

Heijkenskjöld, Filip. "Experimental Techniques for Studies in Atomic & Molecular Physics." Doctoral thesis, Uppsala University, Department of Physics and Materials Science, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-9295.

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This thesis is based on a selection of six different experimental techniques used for studies in atomic and molecular physics. The techniques analysed in the thesis are compared to find similarities in strategies and ways to avoid sources of error.

Paper 1 deals with collision based spectroscopy with 60 keV Xe6+ ions on sodium and argon gas targets. Information on energy of Rydberg states in Xe5+ is unveiled by optical spectroscopy in the wavelength range from vacuum ultraviolet (VUV) to visible. In paper 2, the fast ion-beam laser spectroscopy (FIBLAS) is adapted for measuring hyperfine structure of barium isotopes in an isotopically pure ion-beam. This techniques involves changing the isotope during the measurement to minimize sources of error in measurement and enhance the signal from lesser abundant isotopes. The FIBLAS technique is used in paper 3 to study samarium ions. The ions are optically pumped and the recorded optical nutation is used to measure transition probabilities. This technique eludes the difficulties inherent in relative intensity measurements of all the radiative transitions from an excited state. In Paper 4, optical emission spectroscopy is used in the VUV region to study noble gas mixture discharges. The source of the emission bands near the resonance lines of krypton and xenon are found to be heteronuclear dimers. In paper 5, radiation from a pulsed argon plasma with admixture of nitrogen is studied with time resolved spectroscopy in the VUV and ultraviolet wavelength ranges to investigate the mechanism of energy transport. A metastable state of atomic argon is found to be an important source of energy to many radiative processes. In Paper 6, photoelectron spectroscopy (PES) on thiophene, on 3-bromothiophene and on 3,4-dibromothiophene using time-of-flight photoelectron-photoelectron coincidence technique and conventional PES to investigate the onset of double ionisation compared to the onset of single ionisation in molecules.

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Luttermoser, Donald G. "The Infrared Spectra of Mira Stars." Digital Commons @ East Tennessee State University, 2014. https://dc.etsu.edu/etsu-works/711.

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Over the past two decades, much has been learned about the atmospheric structure of the pulsating Mira-type variable stars from computer modeling and the analysis of ultraviolet and visible wavelength spectra. This talk reports on the first set of infrared spectra taken of these stars under high dispersion with the Infrared Spectrograph (IRS) onboard the Spitzer Space Telescope. A sample of 25 galactic Miras was observed in the 10-37 micron spectral regime anywhere from two to several times during their pulsation cycle. Many of the stars observed show marked changes in overall flux levels as a function of phase. We are able to identify many strong emission lines from neutral and singly ionized metals and emission features due to silicate and carbon dusts and molecular constituents. This work was financially supported through a NASA Spitzer grant for Program GO 50717.

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Shevlin, Stephen Andrew. "A theoretical study of the atomic and electronic structures of three prospective atomic scale wire systems." Thesis, University College London (University of London), 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.367561.

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43

Moretto, Therese. "Structure and properties of hadrons at zero and finite temperature." Thesis, University of Oxford, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.335764.

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Zhang, Kaikai. "Atomic and Molecular dynamics in intense mid-infrared fields." The Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1440204616.

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Hyams, Peter Alan. "Ab initio calculations of molecular structure and properties using the spin-coupled wavefunction." Thesis, University of Bristol, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.279733.

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Sahm, David Karl. "The classical mechanics of mode-mode energy transfer in polyatomic molecules." Diss., Georgia Institute of Technology, 1990. http://hdl.handle.net/1853/29997.

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Mead, Robert Nielle. "Molecular dynamics modelling of the amorphous calcium silicate and titania silicate atomic-scale structure." Thesis, University of Kent, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.443767.

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Stepanian, S. G., A. Yu Ivanov, and L. Adamowicz. "Effect of low-temperature argon matrices on the IR spectra and structure of flexible N-acetylglycine molecules." AMER INST PHYSICS, 2016. http://hdl.handle.net/10150/622884.

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A study of how the matrix environment impacts the structure and IR spectra of N-acetylglycine conformers. The conformational composition of this compound is determined according to an analysis of the FTIR spectra of N-acetylglycine isolated in low temperature argon matrices. Bands of three N-acetylglycine conformers are identified based on the spectra: one major and two minor. The structure of all observed conformers is stabilized by different intramolecular hydrogen bonds. The Gibbs free energies of the conformers were calculated (CCSD(T)/CBS method), and these energy values were used to calculate conformer population at a temperature of 360 K, of which 85.3% belonged to the main conformer, and 9.6% and 5.1% to the minor conformers. We also determined the size and shape of the cavities that form when the N-acetylglycine conformers are embedded in the argon crystal during matrix deposition. It is established that the most energetically favorable cavity for the planar main conformer is the cavity that forms when 7 argon atoms are replaced. At the same time, bulky minor conformers were embedded into cavities that correspond to 8 removed argon atoms. We calculated the complexation energy between argon clusters and conformers, and the deformation energy of the argon crystal and the N-acetylglycine conformers. The matrix-induced shifts to the conformer oscillation frequency are calculated. Published by AIP Publishing.

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Swanlund, John M. "ELECTRONIC STRUCTURE OF CATHODE MATERIALS IN LITHIUM ION BATTERIES." VCU Scholars Compass, 2019. https://scholarscompass.vcu.edu/etd/5851.

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Lithium ion batteries are ubiquitous in modern life, from powering hand-held electronic devices to electric vehicles. And with the necessary drive toward renewable energy sources like solar and wind, electricity storage for the grid promises to drive up the demand for higher performing, less expensive, safer, and more environmentally friendly secondary batteries. Recent research has theorized that replacing halogens in batteries’ electrolytes with non-halogens can yield desirable performance characteristics while eliminating the most dangerous and problematic chemicals. This thesis explores the possibility that a similar approach can be taken with the cathodes of lithium ion batteries. The active material in a cathode is a salt composed of an alkali cation – the positive lithium ion, and a negative ion – usually a metal oxide. Replacing the negative ion with a superhalogen, which is more electronegative than the most electronegative element, may yield comparable electronic properties to current cathode materials while also opening up opportunities to research materials previously not considered for lithium ion battery cathodes.

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Mavroidis, Athanasios. "A QCD analysis of structure function data from electron proton collisions in the H1 experiment." Thesis, Queen Mary, University of London, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.243432.

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Dissertations / Theses on the topic 'Atomic/Molecular Structure and Spectra'

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