Dissertations / Theses: 'Ultraviolet spectroscopy'

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Roberge, Aki. "Ultraviolet spectroscopy of circumstellar disks." Available to US Hopkins community, 2002. http://wwwlib.umi.com/dissertations/dlnow/3068203.

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Gianola, Adam J. "Ultraviolet photoelectron spectroscopy of organic anions." Diss., Connect to online resource, 2006. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3219005.

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Miller, Bradley E. "Vacuum ultraviolet laser spectroscopy of small molecules." Diss., Georgia Institute of Technology, 1987. http://hdl.handle.net/1853/27891.

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Scully, Shane William James. "Negative photoion spectroscopy in the extreme ultraviolet." Thesis, Queen's University Belfast, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.484323.

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Del, Zanna Giulio. "Extreme ultraviolet spectroscopy of the solar corona." Thesis, University of Central Lancashire, 1999. http://clok.uclan.ac.uk/7916/.

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New Extreme Ultra-Violet (EUV) observations of the solar corona, obtained by the Coronal Diagnostic Spectrometer (CDS) instrument on board the NASA/ESA Solar and Heliospheric Observatory (SOHO) are presented. The CDS instrument for the first time has provided the opportunity of observing a large number of emission lines from a wide range of ions of different elements. The spectral and spatial resolution of the CDS instrument has allowed the simultaneous application of a wide range of spectroscopic diagnostic techniques to determine the temperature distribution, densities and elemental abundances in the solar plasma. A differential emission measure (DEM) diagnostic technique has been used to infer the temperature structure and the element abundances. The importance of including DEM effects in the element abundance analysis is demonstrated. A complete in-flight cross-calibration between all the CDS detectors (NIS and €115, 150-785 A), is presented here for the first time. The level of accuracy and completeness of the CHIANTI atomic database, used throughout this thesis, has allowed the identification of the many hundreds of spectral lines observed in the CDS spectra, resulting in several new line identifications. An assessment of the €115 solar spectra is presented, showing that, in spite of complexities, €115 spectra are useful for diagnostic analyses. Many discrepancies (in particular with the Li-like ions) between theory and CDS observations are highlighted. It is shown that some of these may be explained by inaccurate ionization equilibrium calculations. Coronal hole densities, temperatures, DEMs, and relative element abundances from both off-limb (plume and inter-plume regions) and on-disc observations are derived and compared with quiet sun values. These included (August 1996) a large equatorial hole, the Elephant's Trunk, probably the best example of a coronal hole observed by SOHO. Coronal hole densities in both coronal (N 1x10 8 cm 3 ) and transition region (Ne = lxlO'° cm 3 ) plasma were found to be about a factor of 2 lower than in the quiet sun, with much lower emission measures at temperatures above 106 K. Moreover, in the transition region, the cell-centres in both coronal holes and quiet sun regions show consistently higher densities (factor of 2) compared to those in the network. Relative element abundances show approximately photospheric values for the coronal holes, with an indication of element abundance variation .(neon in particular) with the supergranular structure. On-disc EUV observations of coronal hole plumes have been performed. This allowed a spectroscopic characterisation of plumes to be obtained for the first time, leading to the first identification of a low-latitude plume near sun-centre. Plumes are shown to be quasi-isothermal structures, with temperatures T 7 - 8x10 5 K. Abundance analyses (using transition region lines) reveal a small FIP effect in these plumes, together with a decreased Ne/O abundance ratio (compared to photospheric).

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Millar, Sean Charles. "Ultraviolet photoelectron spectroscopy of metals and alloys." Thesis, University of Liverpool, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.328146.

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Carlson, David R. "Frequency Combs for Spectroscopy in the Vacuum Ultraviolet." Diss., The University of Arizona, 2016. http://hdl.handle.net/10150/612874.

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This dissertation explores frequency comb spectroscopy and, in particular, its extension to the vacuum-ultraviolet (VUV) and extreme-ultraviolet (XUV) wavelength regimes through a technique called intracavity high harmonic generation (IHHG). By combining the techniques of passive pulse amplification in an enhancement cavity with high harmonic generation, IHHG enables the direct conversion of near-infrared radiation to the VUV/XUV while still maintaining the underlying comb structure .As part of this work, a series of numerical simulations was performed to investigate the plasma that is formed in the IHHG process and its implications for the resulting VUV comb. It was demonstrated that a fundamental limitation to the performance of IHHG experiments is due to the single-pass ionization phase shift acquired by the pulse circulating in the enhancement cavity. Furthermore, we showed that a static background plasma accumulates between pulses and complicates cavity stabilization. Insights gained from the simulations led to the development of a novel pump-probe technique using the enhancement cavity that allowed a direct measurement of the intracavity plasma and its decay dynamics in real-time. Because the plasma lifetime plays such a crucial role in the operation of these cavities, it was important to have a method to test ways of reducing it. To build on our initial IHHG results showing record-level powers in the XUV, we implemented a fully phase-coherent dual comb spectrometer consisting of two identical IHHG systems operating in parallel. The system is designed for precision spectroscopy in the VUV and is based on a pair of homemade ytterbium fiber lasers that use a parabolic amplification scheme to achieve 80 fs pulses after amplification to 50 W of average power. Initial dual comb data showing system performance at the fundamental frequency and third harmonic are presented.

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Richmond, A. M. "Vacuum ultraviolet discharge excited lasers." Thesis, University of Oxford, 1987. http://ora.ox.ac.uk/objects/uuid:3a09736b-bffb-4ac9-b57c-fb9daa1c8484.

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The thesis concerns experimental studies of discharge excited lasers operating in the vacuum ultraviolet (VUV) region of the spectrum. The known molecular fluorine laser operating at 157nm, on a bound- to-bound transition of the F₂ molecule was selected for initial study. As a result of the work reported here the energy per pulse was increased by a factor of five (10mJ to 50mJ) from that of earlier F₂ lasers. Similary the working lifetime of the gas mixture was increased from a few shots to several thousand by the application of cryogenic gas purification techniques. These improvements have resulted in the development of a practical commercial F₂ laser. The performance characteristics of the fluorine laser and their relationship to the physical mechanisms are discussed. With the objective of achieving laser action in the 110 to 130nm region of the VUV a novel scheme is investigated. The scheme involves the production of a population inversion between the v'=1 level of the b¹π_u state of molecular nitrogen and high lying levels of the X¹Σ_g ground state. The excitation of the upper laser level involves production of N₂ molecules in the a¹π_g state by means of a pulsed discharge. Transfer of population from this intermediate 'a' state to the upper level is accomplished by absorption of radiation at 308nm from a discharge excited xenon chloride laser. The practicality of this scheme has been investigated to the extent that populations of the order of 10¹³ molecules per cm³ have been produced in the 'a' state and laser induced fluorescence on the 'b' to 'X' band has been observed. Under the conditions of "the present experiments the potential VUV gain is too small (10^-4cm^{-1>/sup>) to reach laser threshold. The problems of increasing the gain to reach threshold for a practical device are discussed.}

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HUTH, THOMAS CARL. "ANALYTICAL MASS SPECTROMETRY WITH A SELECTIVE VACUUM ULTRAVIOLET PHOTOIONIZATION SOURCE." Diss., The University of Arizona, 1986. http://hdl.handle.net/10150/183916.

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The vacuum ultraviolet molecular hydrogen laser is evaluated as a selective ion source for analytical mass spectrometry of easily-ionized compounds. The types of compounds ionized below the photon energy of 7.8 eV include polynuclear aromatic hydrocarbons, and many amines and nitrogen-containing heterocycles. The latter two categories encompass a large number of pharmaceuticals and drugs of abuse. H₂ laser photoionization produces parent molecular ions only, for all compounds studied thus far. Selectivity of the threshold photoionization process is very high, as compounds within as little as 0.2 eV above the threshold are completely rejected. The ability of the technique to discriminate against interfering matrix components is demonstrated for both simple synthetic and complex "real world" mixtures. Easily interpreted spectra are obtained from simple extracts of spiked coffee, beer, soy sauce, urine and blood serum. The most important interference is shown to be electron impact ionization arising from acceleration of stray electrons in the ion source. Most of this ionization is caused by low-energy secondaries generated when stray primaries are collected by the ion source electrodes. The primaries are produced mainly by interaction of scattered laser radiation with metal surfaces. This interference can be controlled through proper instrumental design.

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Huisinga, Marten. "Ultraviolet photoelectron spectroscopy and electron stimulated desorption from CaF2." [S.l. : s.n.], 1998. http://www.diss.fu-berlin.de/1999/24/index.html.

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Mao, Dunmin. "Vacuum ultraviolet laser spectroscopy of the rare gas dimers." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape3/PQDD_0015/NQ58150.pdf.

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Fish, Deborah Jane. "Measurement of stratospheric composition using ultraviolet and visible spectroscopy." Thesis, University of Cambridge, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.360887.

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Judge, P. G. "Ultraviolet spectroscopy of late-type giant and supergiant stars." Thesis, University of Oxford, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.354829.

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Boustany, Nada. "Characterization of mucosal dysplasia with ultraviolet resonance Raman spectroscopy." Thesis, Massachusetts Institute of Technology, 1997. http://hdl.handle.net/1721.1/9809.

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Thesis (Ph. D.)--Harvard--Massachusetts Institute of Technology Division of Health Sciences and Technology, 1997.
"August, 1997."
Includes bibliographical references.
by Nada Boustany.
Ph.D.

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Adamopoulos, Georges. "Visible and ultraviolet Raman spectroscopy of diamond-like carbon." Thesis, University of Cambridge, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.621148.

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Graham, David Robert. "Extreme ultraviolet spectroscopy of impulsive phase solar flare footpoints." Thesis, University of Glasgow, 2014. http://theses.gla.ac.uk/5017/.

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This thesis is primarily concerned with the atmospheric structure of footpoints during the impulsive phase of a solar flare. Through spectroscopic diagnostics in Extreme- Ultraviolet wavelengths we have made significant progress in understanding the depth of flare heating within the atmosphere, and the energy transport processes within the footpoint. Chapter 1. introduces the Sun and its outer atmosphere, forming the necessary background to understand the mechanisms behind a solar flare and their observational characteristics. The standard flare model is presented which explains the energy source behind a flare, through to the creation of the EUV and X-ray emission. In Chapter 2 the basics of atomic emission line spectroscopy are introduced, covering the processes driving electron excitation and de-excitation, the formation of Gaussian line profiles, and the formation of density sensitive line ratios. The concept of a differ-ential emission measure is also derived from first principles, followed by a description of all of the instruments used throughout this thesis. Chapter 3 presents measurements of electron density enhancements in solar flare footpoints using diagnostics from Hinode/EIS. Using RHESSI imaging and spectroscopy, the density enhancements are found at the location of hard X-ray footpoints and are interpreted as the heating of layers of increasing depth in the chromosphere to coronal temperatures. Chapter 4 shows the first footpoint emission measure distributions (EMD) obtained from Hinode/EIS data. A regularised inversion method was used to obtain the EMD from emission line intensities. The gradient of the EMDs were found to be compatible with a model where the flare energy input is deposited in an upper layer of the flare chromosphere. This top layer then cools by a conductive flux to the denser plasma below which then radiates to balance the conductive input. The EUV footpoints are found to be not heated directly by the injected flare energy. In Chapter 5 electron densities of over 1013 cm−3 were found using a diagnostic at transition region temperatures. It was shown to be difficult to heat plasma at these depths with a thick-target flare model and several suggestions are made to explain this; including optical depth effects, non-ionisation equilibrium, and model inaccuracies. Finally, Chapter 6 gathered together both the density diagnostic and EMD results to attempt to forward fit model atmospheres to observations using a Genetic Algorithm. The results are preliminary, but progress has been made to obtain information about the T (z) and n(z) profiles of the atmosphere via observation.

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Šiffalovič, Peter. "Femtosecond time resolved photoelectron spectroscopy in the extreme ultraviolet region." [S.l.] : [s.n.], 2002. http://deposit.ddb.de/cgi-bin/dokserv?idn=964973502.

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Tobey, Ra'anan Itzhak. "Linear and nonlinear photo-acoustic spectroscopy with extreme ultraviolet radiation." Diss., Connect to online resource, 2006. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3207721.

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Hippler, Michael Felix Anton. "Ultraviolet laser spectroscopy of nitric oxide : analytical and dynamical applications." Thesis, Heriot-Watt University, 1993. http://hdl.handle.net/10399/1457.

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Hooper, Nicole. "Some studies of small reactive intermediates with ultraviolet photoelectron spectroscopy." Thesis, University of Southampton, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.252045.

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Flexen, Alexander C. "Vacuum ultraviolet laser spectroscopy of diatomic halogen and interhalogen molecules." Thesis, University of Edinburgh, 1999. http://hdl.handle.net/1842/13824.

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The Rydberg and ion-pair states of Cl₂, Br₂, I₂, ICl and IBr have been studied using a range of laser-based spectroscopic techniques, in the vacuum-ultraviolet (VUV) energy region. The [2+1] resonance enhanced multiphoton ionization (REMPI) spectrum of Br₂ has been re-examined in the region 56 000-86 000 cm^-1. Rydberg series, previously assigned to components of the ns Rydberg states have been reassigned to components of the (n-2)d Rydberg states, for n≥6. The lowest 5s Rydberg state components on each ionic core remain unchanged, based on energetic considerations. The Ω values of the Rydberg states were deduced from rotational band contour analysis and from intensity ratios under linear and circular polarization. A propensity rule for assignments based on two Ω components with significant singlet character (Ω=0 and Ω=2), on each ionic core, was determined in terms of the microconfigurations for the Hund's case (c) states. As an exception, triplet components (Ω=1) are also observed for the lowest n in a particular Rydberg series (n=4 for the d-series in Br₂). This reassignment prompted a reinvestigation of the one- and two-photon spectra of the halogen and interhalogen molecules, Cl₂ I₂, ICl and IBr in terms of the propensity rules developed for Br₂. The one-photon spectra of I₂ and ICl were recorded using VUV laser radiation, generated by four-wave mixing in Kr gas. Ion-pair formation (X⁺+Y^-) via predissociation of Rydberg states was observed from all states seen in the one-photon absorption spectrum of each molecule. Spectra were recorded from the ion-pair threshold up to the ionization limit. The field-lowering effect induced by the high electric field in the extraction region of the time-of-flight mass spectrometer was investigated with I₂. Predissociation in I₂ and ICl is discussed in terms of a two-electron exchange mechanism connecting the electronic configurations of the Rydberg and ion-pair states.

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Nakagawa, Akinari. "Methodological advances in ultraviolet spectroscopy of the extended solar corona." 京都大学 (Kyoto University), 2007. http://hdl.handle.net/2433/136954.

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Natarajan, Shweta. "Thermal metrology techniques for ultraviolet light emitting diodes." Thesis, Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/45891.

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AlₓGa₁₋ₓN (x>0.6) based Ultraviolet Light Emitting Diodes (UV LEDs) emit in the UV C range of 200 - 290 nm and suffer from low external quantum efficiencies (EQEs) of less than 3%. This low EQE is representative of a large number of non-radiative recombination events in the multiple quantum well (MQW) layers, which leads to high device temperatures due to self-heating at the device junction. Knowledge of the device temperature is essential to implement and evaluate appropriate thermal management techniques, in order to mitigate optical degradation and lifetime reduction due to thermal overstress. The micro-scale nature of these devices and the presence of large temperature gradients in the multilayered device structure merit the use of several indirect temperature measurement techniques to resolve device temperatures. This work will study UV LEDs with AlₓGa₁₋ₓN active layers, grown on sapphire or AlN growth substrates, and flip-chip mounted onto submounts and package configurations with different thermal properties. Thermal metrology results will be presented for devices with different electrode geometries (i.e., interdigitated and micropixel), for bulk and thinned growth substrates. The body of this work will present a comparative study of optical techniques such as Infrared (IR), micro-Raman and Electroluminescence (EL) spectroscopy for the thermal metrology of UV LEDs. The presence of horizontal and vertical temperature gradients within the device layers will be studied using micro-Raman spectroscopy, while the occurrence of thermal anomalies such as hotspots and shorting paths will be studied using IR spectroscopy. The Forward Voltage (Vf) method, an electrical junction temperature measurement technique, will also be investigated. The Vf method will be applied to the Thermal Resistance Analysis by Induced Transient (TRAIT) procedure, whereby electrical data at short time scales from an operational device will be used to discretize the junction-to- package thermal resistance pathway from the total junction- to-ambient heat path. The TRAIT procedure will be conducted on several LEDs, for comparison. The scope and applicability of each thermal metrology technique will be examined, and the merits and demerits of each technique will be exhibited.

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Lewis, Brenton R. "Excited states of atmospheric molecules: spectra, structures and interactions : a thesis submitted for the degree of Doctor of Science of the University of Adelaide /." Title page, contents and abstract only, 2000. http://web4.library.adelaide.edu.au/theses/09SD/09sdl673.pdf.

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Austin, Derek Ian. "Analysis of the vacuum ultraviolet spectra of Br₂, lBr and ICI." Thesis, University of Edinburgh, 1987. http://hdl.handle.net/1842/10679.

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Lamarre, Nicolas. "Photoexcitation et relaxation de cyanopolyynes en phase gazeuse dans le domaine de l'ultraviolet du vide." Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLS167/document.

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Ce travail de thèse, essentiellement de nature expérimentale, s’inscrit dans le domaine de la physique moléculaire en phase gazeuse avec des applications en astrophysique. Il porte sur l’étude de la photoexcitation et de la relaxation de molécules de la famille des cyanopolyynes qui sont détectées dans plusieurs objets du milieu interstellaire (nuages moléculaires, comètes) et dans les atmosphères planétaires comme celle de Titan. Ces composés participent à la chimie du carbone dans ces milieux en interagissant avec le rayonnement interstellaire ou avec le flux solaire dans le domaine spectral de l’ultraviolet du vide (VUV). La structure électronique excitée de plusieurs cyanopolyynes neutres a été étudiée avec la spectroscopie d’absorption par transformée de Fourier. Ces expériences ont permis d’identifier les états de Rydberg et de mesurer la section efficace absolue de photoabsorption. Parmi les processus de relaxation ouverts suite à la photoexcitation VUV, les voies d’ionisation et d’ionisation dissociative ont été explorées de façon détaillée à l’aide du rayonnement synchrotron SOLEIL ou du rayonnement laser du Centre Laser de l'Université Paris-Sud. Des informations variées (potentiels d’ionisation vers les premiers états électroniques, fréquences vibrationnelles, couplages vibroniques, etc) ont été obtenues sur les cations de cyanopolyynes via l’utilisation de la spectroscopie de photoélectrons de seuil et de la spectroscopie de photoélectrons d’énergie cinétique nulle. Enfin, la détection par spectrométrie de masse des fragments cationiques issus de l’ionisation dissociative a permis de mesurer leur énergie d’apparition et de déterminer leur voie de formation à l’aide de calculs DFT menés par un collaborateur
This PhD thesis presents essentially an experimental work dealing with gas-phase molecular physics with astrophysical applications. The goal of the PhD is the study of the photoexcitation and relaxation of cyanopolyyne molecules that have been detected in different interstellar objects (molecular clouds, comets), and in planetary atmospheres (e.g. Titan). These molecules contribute to the carbon chemistry of these media by interacting with the interstellar radiation or with the solar flux in the vacuum ultraviolet range (VUV). The excited electronic structure of neutral cyanopolyynes was studied by absorption spectroscopy with a VUV Fourier-transform spectrometer. These experiments allowed us to identify the Rydberg states, and to measure the absolute photoabsorption cross section.Among the different open relaxation processes following a VUV photoexcitation, ionisation and dissociative ionisation have been investigated in detail using SOLEIL synchrotron radiation or laser sources of Centre Laser de l’Université Paris-Sud. Data on the ionisation potentials toward the first electronic states, vibrational frequencies, vibronic couplings, etc. were obtained on cyanopolyyne cations with the use of threshold photoelectron spectroscopy and zero-kinetic-energy photelectron spectroscopy. Finally, cationic species created by dissociative ionisation of cyanopolyynes were detected by mass spectrometry. The threshold energies were measured and the formation channel of these fragments was determined with the help of DFT calculations performed by a collaborator

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Steinmann, C. M. (Christine Margarete). "Vacuum ultraviolet laser spectroscopy of CO molecules in a supersonic jet." Thesis, Stellenbosch : Stellenbosch University, 2003. http://hdl.handle.net/10019.1/53709.

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Thesis (PhD)--Stellenbosch University, 2003.
ENGLISH ABSTRACT: A tunable narrow-bandwidth laser source combined with a supersonic gas jet as sample is wellsuited for obtaining high-resolution spectra of cold isolated molecules and complexes. In the present study such a laser source in the vacuum ultraviolet was applied to the spectroscopic investigation of rare carbon monoxide (CO) isotopomers and CO-noble gas van der Waals complexes in supersonic gas pulses seeded with natural CO gas. Tunable coherent vacuum ultraviolet radiation was generated by two-photon resonant fourwave sum-frequency mixing of two pulsed dye laser beams in a magnesium vapour medium. Laser induced fluorescence excitation spectra of the A(v'=3)-X(v"=0) vibronic band of CO molecules in a noble gas (neon or argon) jet were obtained by measuring the total undispersed fluorescence from the irradiated sample volume in dependence of the excitation wavelength. The dynamics of the flow-cooling process in the supersonic jet were investigated and the experimental parameters optimised using the rotational temperature of 12C160as determined from rotational line intensities. Rotational temperatures as low as 2 ± I K were observed. Spectroscopic detection of the rare 12C170and 12C180isotopomers was facilitated by the low rotational temperature and high spectral resolution. Six rotational lines of 12C170and four of 12C180were detected in the A(v'=3)-X(v"=0) vibronic band. This demonstrates the low detection limit (circa 3 parts per million) obtained in the experiment. The line wavelengths were determined to an accuracy of 0.2 pm using the well-documented 12C160and 13C160lines for calibration. The spectral results on 12C170are, to our knowledge, the first rotationally resolved laboratory measurements published on the A-X band of this isotopomer. Accurate wavelength data of the stable isotopomers of CO is of importance in the interpretation of astrophysical observations of CO in the interstellar medium. The newly determined 12C170wavelengths were successfully applied to a recent problem in astrophysics (Astrophys. J. Lett. 2003). The conditions in a supersonic jet facilitate the study of weakly bound van der Waals complexes, of which CO-noble gas complexes are prototypes. However, there is no experimental data available on the electronic excitation spectra of the CO-noble gas complexes, lying in the vacuum ultraviolet region. In the present experiment evidence of extensive complexation of the CO in the noble gas jet has been found, but in the spectral region around the A(v'=3)-X(v"=O) band of CO no distinct spectral features that could be associated with these complexes were observed. Having considered the existing knowledge on CO and CO-noble gas complexes and experimental studies on the excitation and dissociation dynamics of Iz-noble gas complexes, we regard complex induced inter-system crossing or electronic predissociation as the most likely causes for these observations. The results on the rare CO isotopomers demonstrate the potential of our experimental setup for high-resolution, isotope and state selective spectroscopy in the vacuum ultraviolet with a high sensitivity for fluorescent species. The availability of the now well-characterised experimental setup in our laboratory opens the way for further investigation of molecular or complex species with spectroscopic features in the vacuum ultraviolet region.
AFRIKAANSE OPSOMMING: Vakuum ultraviolet laser spektroskopie van CO molekules in 'n supersoniese gasstraal: 'n Afstembare smal bandwydte laserbron en 'n supersoniese gasstraal as monster is 'n geskikte kombinasie vir hoë-resolusie spektroskopie van geïsoleerde afgekoelde molekules en komplekse. In hierdie studie is so 'n laserbron in die vakuum ultraviolet gebruik in die spektroskopiese ondersoek van skaars koolstofmonoksied (CO) isotopomere en CO-edelgas van der Waals komplekse in supersoniese gaspulse wat 'n klein persentasie natuurlike CO gas bevat. Afstembare koherente vakuum ultraviolet lig is verkry deur twee-foton resonante vier-golf som-frekwensie vermenging van twee gepulseerde kleurstoflaserbundels in 'n magnesiumdamp medium. Laser-geïnduseerde fluoressensie opwekkingspektra van die A(v'=3)-X(v"=0) vibroniese band van die CO molekules in die edelgasstraal (neon of argon) is uitgemeet deur die totale fluoressensie van die beligte gasmonster, sonder golflengteskeiding, te meet as funksie van die opwekkingsgolflengte. Die dinamika van die vloeiverkoelingsproses in die supersoniese gasstraal is ondersoek en die eksperimentele parameters geoptimeer deur gebruik te maak van die rotasionele temperatuur van 12Cl60 soos bepaal uit die intensiteitsverhoudings van die rotasielyne. Rotasionele temperature tot so laag as 2 ± 1 K is waargeneem. Spektroskopiese waarneming van die skaars 12C170 and 12Cl80 isotopomere is moontlik gemaak deur die lae rotasionele temperatuur en die hoë spektrale resolusie. Ses rotasielyne van 12C170 en vier van 12C180 is waargeneem in die A(v'=3)-X(v"=0) vibroniese band. Dit demonstreer die lae deteksielimiet (ongeveer 3 dele per miljoen) wat bereik kon word. Die golflengtes van die lyne is bepaal met 'n akkuraatheid van 0.2 pm deur die bekende lyne van 12C160en 13C160vir kalibrasie te gebruik. Die resultate ten opsigte van 12C170 is sover vasgestel kon word die eerste rotasioneel-opgeloste laboratorium metings van die A-X band van hierdie isotopomeer. Akkurate golflengte data vir die stabiele CO isotopomere is van belang vir die interpretasie van die astrofisiese waarnemings van CO in die interstellêre medium. Die nuwe 12C170 golflengtes is suksesvol aangewend in die oplossing van 'n onlangse interpretasieprobleem in astrofisika (Astrophys. J. Lett. 2003). Die toestande in 'n supersoniese gasstraal maak die bestudering van swak-gebonde van der Waals komplekse moontlik. Hoewel CO-edelgas van der Waals komplekse as prototipes beskou word, is daar geen eksperimentele data beskikbaar oor die elektroniese opwekkingspektra van hierdie spesies, wat in die vakuum ultraviolet gebied lê, nie. In hierdie studie is daar eksperimentele getuienis gevind vir uitgebreide kompleksering van CO in die edelgasstraal, maar in die spektraalgebied rondom die A(v'=3)-X(v"=O) band van CO is geen duidelike spektrale kenmerke wat met hierdie komplekse geassosieer kan word, waargeneem nie. Na oorweging van die bestaande kennins oor CO en CO-edelgas komplekse en eksperimentele studies oor die opwekking en dissosiasie-dinamika van Iz-edelgas komplekse, beskou ons kompleksgeïnduseerde intersisteemoorgange of elektroniese predissosiasie as die waarskynlikste redes vir hierdie waarnemings. Die resultate oor die skaars CO isotopomere toon die potensiaal van ons eksperimentele opstelling vir hoë-resolusie, isotoop- en toestandselektiewe spektroskopie in die vakuum ultraviolet met uitstekende sensitiwiteit vir fluoresserende spesies. Die beskikbaarheid van hierdie nou deeglik gekarakteriseerde eksperimentele opstelling in ons laboratorium maak verdere ondersoek na molekulêre of kompleks-spesies met spektroskopiese kenmerke in die vakuum ultraviolet moontlik.

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Du, Plessis Anton. "Laser spectroscopy of the Fourth Positive System of carbon monoxide isotopomers." Thesis, Link to the online version, 2006. http://hdl.handle.net/10019.1/1219.

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Huang, Ping. "Diagnostics in VUV laser spectroscopy." Thesis, Stellenbosch : University of Stellenbosch, 2005. http://hdl.handle.net/10019.1/2244.

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Thesis (MSc (Physics))--University of Stellenbosch, 2005.
A tunable vacuum ultra-violet (VUV) laser source was recently developed for VUV spectroscopy using state selective excitation and total fluorescence detection. The VUV laser source makes use of a four-wave mixing process to provide tunable VUV radiation for the electronic excitation of the molecules. The theory of four-wave mixing, with the emphasis on parameters that are important for our experimental setup to generate efficient tunable VUV radiation is discussed. The experimental setup, and in particular the metal vapor heat-pipe, which provides Mg vapor as the nonlinear medium, is described. New diagnostic equipment described in this work was added to the experimental setup. This equipment was characterized and utilized together with the existing setup. The additional diagnostic equipment introduced enabled us to measure the tunable VUV output of the source (using a VUV monochromator), making it possible to significantly improve the efficiency of the existing tunable VUV laser source.

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Iping, R. C., G. Sonneborn, D. L. Massa, D. Gies, and S. Williams. "Far-ultraviolet spectroscopy of O+O binaries in the Magellanic Clouds." Universität Potsdam, 2007. http://opus.kobv.de/ubp/volltexte/2008/1789/.

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We report FUSE observations in 2005–2006 of three O-type, double-lined spectroscopic binaries in the Magellanic Clouds. The systems have very short periods (1.4–2.25 d), represent rare, young evolutionary stages of massive stars and binaries, and provide a unique glimpse at some of the most massive systems that form in dense clusters of massive stars. Improved orbit parameters, including revised masses, for LH54-425 are derived from new ctio spectroscopy. The systems are: LH54-425 in the LMC (O3V + O5V, P=2.25d, 62+37M⊙), J053441-693139 in the LMC (O2-3If+O6V, P=1.4 d, 41+27M⊙), and Hodge 53-47 in the SMC (O6V + O4-5IIIf, P=2.2 d, 24+14M⊙, where the O4 star appears to be less massive than the O6 star). Their short periods indicates that wind interaction and mass transfer are likely important factors in their evolution. The spectra provide quantitative and systematic studies of phase-dependent stellar wind properties, wind collision effects in O+O binaries at lower metallicities, improved radial velocity curves, and FUV spectro-photometric changes as a function of orbital phase.

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Huen, Yin-fan Denis, and 禤彥勳. "Ultraviolet photoemission spectroscopy study of transition metal diselenide cystalline thin films." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2014. http://hdl.handle.net/10722/211146.

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Ali, Sahangir. "Gas phase vacuum-ultraviolet (vuv) spectroscopy of small halogenated polyatomic molecules." Thesis, University of Birmingham, 2007. http://etheses.bham.ac.uk//id/eprint/897/.

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The work carried out in this thesis is concerned with photoexcitation of small and halogenated molecules in the gas phase with vacuum-ultraviolet (VUV) radiation. For all the experiments described in this thesis, the source of radiation was from tuneable VUV radiation from a synchrotron source. The majority of the experiments used the UK national source located at Daresbury Cheshire. Fluorescence spectra were taken using the newly commissioned Wadsworth monochromator on beamline 3.1 of the Daresbury synchrotron radiation source. Dispersed florescence spectra were taken using a newly developed fluorescence apparatus incorporating a multi-channel CCD detection system. One of the objectives of this thesis is to compare the sensitivity and resolution of this new system with that of an apparatus used at the BESSY 1 synchrotron source in the 1990s. Many of the molecules studied here were chosen because previous data recorded at BESSY 1 were available for this comparison. Molecules studied include the MCl\(_4\) series (M = C, Si and Ge) where both the VUV photoabsorption and fluorescence spectra were recorded. A new analysis of the absorption spectra is presented. Emissions are observed in MCl\(_2\), MCl and the parent ion of SiCl\(_4^+\) and GeCl\(_4^+\). The CF\(_3\)X series (X = H, F, Cl, Br, I and SF\(_5\)) where the fluorescence spectra and some photoabsorption spectra were recorded. Emissions are observed in CF, CF\(_2\), CF\(_3\) and parent ion CF\(_4^+\), CF\(_3\)H\(^+\). Undispersed and dispersed fluorescence spectra of BX\(_3\) (X = F, Cl and Br) were also recorded. Emission is now observed in BX\(_2\), BX and parent ion BX\(_3^+\). Finally the fluorescence spectra of PX\(_3\) (X = F, Cl and Br) were recorded and are presented here. Emissions are observed in PX\(_2\), PX and parent ion PX\(_3^+\).

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Simpson, Matthew James. "Ion-molecule reaction mass spectrometry and vacuum-ultraviolet negative photoion spectroscopy." Thesis, University of Birmingham, 2010. http://etheses.bham.ac.uk//id/eprint/1056/.

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Two separate experimental techniques have been used to investigate the fundamental properties of small polyatomic molecules in the gas phase. Selected ion flow tube mass spectrometry has been used to study the reactions of cations and anions with ethene, monofluoroethene, 1,1-difluoroethene, trifluoroethene and tetrafluoroethene. Calculated collisional reaction rate coefficients are compared to those measured by the experiment. The product ions from these reactions have been detected and their branching ratios measured. Many of these results have been explained using arrow-pushing mechanisms. Using tunable vacuum-ultraviolet radiation from a synchrotron, negative ions have been detected following photoexcitation of 24 gaseous molecules. The majority of the molecules studied are halogen-substituted methanes. Product anions resulting from unimolecular ion-pair dissociation reactions were detected, and their ion yields recorded in the range 8-35 eV. Absolute cross sections for ion-pair formation and resulting quantum yields are calculated. This vast collection of data is summarised and ion-pair formation from polyatomic molecules is reviewed.

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Wituschek, Andreas [Verfasser], and Frank [Akademischer Betreuer] Stienkemeier. "Phase-modulated coherent time-domain spectroscopy in the extreme ultraviolet regime." Freiburg : Universität, 2020. http://d-nb.info/1226657095/34.

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35

Nichols, James Warren. "The design of a new far ultraviolet interferometer for ionospheric spectroscopy." Thesis, Monterey, California : Naval Postgraduate School, 1990. http://handle.dtic.mil/100.2/ADA241767.

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Thesis (M.S. in Physics)--Naval Postgraduate School, December 1990.
Thesis Advisor(s): Cleary, David D. ; Davis, D. Scott. "December 1990." Description based on title screen as viewed on April 2, 2010. DTIC Identifier(s): Ionosphere, Ultraviolet Spectroscopy, Interferometer. Author(s) subject terms: Ionosphere, Ultraviolet Spectroscopy, Interferometer. Includes bibliographical references (p. 64-67). Also available in print.

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Williams, Elmer. "The electronic spectra of AlBr, GaF, InCl, and CO⁺ /." The Ohio State University, 1985. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487264603218008.

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37

Murray, D. Jay. "Modeled and observed N₂ Lyman-Birge-Hopfield band emissions in the Earth's dayglow a comparison /." Orlando, Fla. : University of Central Florida, 2007. http://purl.fcla.edu/fcla/etd/CFE0001986.

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Gray, Jean Marie. "Design and first operations of the Lineate Imaging Near-Ultraviolet Spectrometer (LINUS)." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2002. http://library.nps.navy.mil/uhtbin/hyperion-image/02Dec%5FGray%5FJean.pdf.

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Thesis (M.S. in Applied Physics)--Naval Postgraduate School, December 2002.
Thesis advisor(s): Richard C. Olsen, Richard Harkins. Includes bibliographical references (p. 37). Also available online.

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Baskakov, S. A., V. N. Vasilets, and Y. M. Shulga. "Vacuum Ultraviolet Assisted Photoreduction of Graphene Oxide Nanosheets." Thesis, Sumy State University, 2012. http://essuir.sumdu.edu.ua/handle/123456789/34809.

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Films of graphene oxide nanosheets have been prepared by deposition from an aqueous alcohol emulsion onto a Teflon FEP substrate. The behavior of the films exposed to monochromatic vacuum UV radiation at a wavelength of 123.6 nm has been studied. The decrease of water content and the amount of hydroxyl (OH) groups as well as the increases of the concentration of double bonds in the film has been found after irradiation. At the same time the amount of C=O remains constant in the carboxyl and ketone groups. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/34809

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O'Shay, Joseph Fred. "Time-resolved visible and extreme ultraviolet spectroscopy of laser-produced tin plasma." Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2007. http://wwwlib.umi.com/cr/ucsd/fullcit?p3264604.

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Thesis (Ph. D.)--University of California, San Diego, 2007.
Title from first page of PDF file (viewed August 7, 2007). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references (p. 248-255).

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Melamed, Megan Louise. "Aircraft-based ultraviolet spectroscopy measurements of sulfur dioxide emissions from point sources." Diss., Connect to online resource, 2006. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3239432.

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Mohamed-Tahrin, Norhaslinda. "Ground-based zenith-sky measurements of stratospheric BrO by ultraviolet absorption spectroscopy." Thesis, University of Cambridge, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.620660.

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43

Short, Billy Joe. "Ultraviolet resonance Raman enhancements in the detection of explosives." Thesis, Monterey, Calif. : Naval Postgraduate School, 2009. http://edocs.nps.edu/npspubs/scholarly/theses/2009/Jun/09Jun%5FShort.pdf.

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Thesis (M.S. in Applied Physics)--Naval Postgraduate School, June 2009.
Thesis Advisor(s): Smith, Craig F. "June 2009." Description based on title screen as viewed on 14 July 2009. Author(s) subject terms: Raman spectroscopy, standoff detection, high explosives, explosive detection, inelastic scattering, resonance Raman. Includes bibliographical references (p. 77-80). Also available in print.

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44

Whitechurch, C. "A study of the spectroscopy and kinetics of excited radicals by ultraviolet photodissociation." Thesis, University of Manchester, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.374575.

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Rust, Thomas Ludwell. "Explosive Events in the Quiet Sun| Extreme Ultraviolet Imaging Spectroscopy Instrumentation and Observations." Thesis, Montana State University, 2017. http://pqdtopen.proquest.com/#viewpdf?dispub=10607188.

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Explosive event is the name given to slit spectrograph observations of high spectroscopic velocities in solar transition region spectral lines. Explosive events show much variety that cannot yet be explained by a single theory. It is commonly believed that explosive events are powered by magnetic reconnection. The evolution of the line core appears to be an important indicator of which particular reconnection process is at work.

The Multi-Order Solar Extreme Ultraviolet Spectrograph (MOSES) is a novel slitless spectrograph designed for imaging spectroscopy of solar extreme ultraviolet (EUV) spectral lines. The spectrograph design forgoes a slit and images instead at three spectral orders of a concave grating. The images are formed simultaneously so the resulting spatial and spectral information is co-temporal over the 20' × 10' instrument field of view. This is an advantage over slit spectrographs which build a field of view one narrow slit at a time. The cost of co-temporal imaging spectroscopy with the MOSES is increased data complexity relative to slit spectrograph data. The MOSES data must undergo tomographic inversion for recovery of line profiles.

I use the unique data from the MOSES to study transition region explosive events in the He ii 304 Å spectral line. I identify 41 examples of explosive events which include 5 blue shifted jets, 2 red shifted jets, and 10 bi-directional jets. Typical doppler speeds are approximately 100kms^–1. I show the early development of one blue jet and one bi-directional jet and find no acceleration phase at the onset of the event. The bi-directional jets are interesting because they are predicted in models of Petschek reconnection in the transition region.

I develop an inversion algorithm for the MOSES data and test it on synthetic observations of a bi-directional jet. The inversion is based on a multiplicative algebraic reconstruction technique (MART). The inversion successfully reproduces synthetic line profiles. I then use the inversion to study the time evolution of a bi-directional jet. The inverted line profiles show fast doppler shifted components and no measurable line core emission. The blue and red wings of the jet show increasing spatial separation with time.

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Altiere, Emily Elizabeth. "The adventures of Nikita and Casper : high power ultraviolet lasers for precision spectroscopy." Thesis, University of British Columbia, 2014. http://hdl.handle.net/2429/51259.

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The Optically Pumped Semiconductor Laser (OPSL) offers several advantages as a laser source for precision spectroscopy. The semiconductor gain bandwidth allows an OPSL to run continuous wave (CW) between 920 - 1154 nm and with a free running linewidth 500 kHz. High powers have been observed in OPSL, as high as 70 W. Paired with doubling crystals the wavelength range can be extended down to the ultraviolet(UV) with high power. This research presents an OPSL operating at 972 nm at 1.7 W sequentially doubled down twice to a wavelength of 243 nm at 150 mW. The linewidth is reduced by locking one OPSL to a Fabry-Poret stabilization cavity and then the relative linewidth was measured between two OPSL's locked together. The linewidth is determined to be 87 kHz, dominated mostly by technical noise. This laser is set to be used for cryogenic hydrogen spectroscopy and precision measurements of the Lamor precessional frequency of ¹²⁹Xe when it is used as a comagnetometer for measuring the electrical dipole moment (EDM) of the neutron.
Science, Faculty of
Physics and Astronomy, Department of
Graduate

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47

Luz, Roman M. (Roman Manuel) 1979. "Design of an ultraviolet absorption spectroscopy oil concentration sensor for online HVAC measurements." Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/30310.

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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2005.
Includes bibliographical references (p. 58).
Recent advances in the modeling and control of the vapor compression cycle has developed the need for a real time oil concentration rate (OCR) sensor. Because of its ability to give the most accurate online measurements of OCR, ultraviolet absorption spectroscopy has been selected as the measurement approach. Related work in this field is based on models that are unable to make accurate measurements down to zero percent oil concentration. Because of the extremely low OCR of modem HVAC units, the operating range of the sensor must be zero to one percent oil concentration. Improvements to prior models that employ Beer-Lambert's Law will allow the sensor to operate with improved accuracy over the entire operating range. This report details the design of the physical hardware, the analytical modeling, and the calibration methods to build and operate the OCR sensor.
by Roman M. Luz, III.
S.M.

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48

Woo, Hin-Koon. "Two-color photoionization-photoelectron spectroscopy using tunable vacuum ultraviolet and infrared laser sources /." For electronic version search Digital dissertations database. Restricted to UC campuses. Access is free to UC campus dissertations, 2004. http://uclibs.org/PID/11984.

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49

George, Ronie. "Early Ovarian Cancer Detection Using Fluorescence Spectroscopy in the Ultraviolet-C through Visible." Diss., The University of Arizona, 2013. http://hdl.handle.net/10150/301694.

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We evaluate the changes in fluorescence from endogenous fluorophores such as amino acids, structural proteins and enzymatic co-factors to predict malignancy and risk of developing ovarian cancer. 249 ovarian biopsies of the surface epithelium were interrogated in vitro, over 270-550 nm excitation, and fluorescence was collected from 290-700nm. Spectroscopic data was analyzed using parallel factor analysis (PARAFAC) to determine excitation and emission spectra of the underlying fluorophores that contribute to the total detected fluorescence intensity. Using multivariate normal distribution fits and cross-validation techniques, sensitivity (SN) and specificity (SP) of 88 and 93 percent, respectively, were achieved when classifying malignant samples versus others, while 88 and 80 percent, respectively, were achieved when classifying normal post menopausal patients as being either at low- or high-risk of developing ovarian cancer based on their personal and family history of cancer. Also, the performance of classifying cancer increases when the normal group excludes benign neoplasm and endometriosis samples, while the performance of low- v. high-risk decreases when both pre- and post-menopausal samples are included. These results could potentially be useful in screening women at increased risk of developing ovarian cancer. This motivated our study to investigate similar changes in ovarian autofluorescence in vivo. 40 patients were recruited and a total of 189 samples were imaged using a fiber optic bundle and biopsied. Using PARAFAC, the factors computed from in vitro data analysis and in vitro data as a training set; pathology from each in vivo site biopsied was compared to calibrated tissue-fluorescence. It resulted in a SN and SP of 100 and 94 percent, respectively, for classifying normal versus malignant. In the case of risk assessment, cross validated in vivo data gave a SN and SP of 68 and 93%. Results obtained were consistent with those obtained in vitro, except for the presence of blood absorption peaks which affected risk assessment. Assessing endogenous fluorescence has diagnostic potential and if adapted to trans-vaginal access, would make the screening procedure less costly and less invasive, and would be most useful and economical in women at increased risk of developing ovarian cancer and might determine the ideal time to undergo an oophorectomy.

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Szilagyi, John Michael. "Extreme ultraviolet spectral streak camera." Master's thesis, University of Central Florida, 2010. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/4578.

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The recent development of extreme ultraviolet (EUV) sources has increased the need for diagnostic tools, and has opened up a previously limited portion of the spectrum. With ultrafast laser systems and spectroscopy moving into shorter timescales and wavelengths, the need for nanosecond scale imaging of EUV is increasing. EUV's high absorption has limited the number of imaging options due to the many atomic resonances in this spectrum. Currently EUV is imaged with photodiodes and X-ray CCDs. However photodiodes are limited in that they can only resolve intensity with respect to time and X-ray CCDs are limited to temporal resolution in the microsecond range. This work shows a novel approach to imaging EUV light over a nanosecond time scale, by using an EUV scintillator to convert EUV to visible light imaged by a conventional streak camera. A laser produced plasma, using a mass-limited tin based target, provided EUV light which was imaged by a grazing incidence flat field spectrometer onto a Ce:YAG scintillator. The EUV spectrum (5 nm-20 nm) provided by the spectrometer is filter by a zirconium filter and then converted by the scintillator to visible light (550 nm) which can then be imaged with conventional optics. Visible light was imaged by an electron image tube based streak camera. The streak camera converts the visible light image to an electron image using a photocathode, and sweeps the image across a recording medium. The streak camera also provides amplification and gating of the image by the means of a micro channel plate, within the image tube, to compensate for low EUV intensities. The system provides 42 ns streaked images of light with a temporal resolution of 440 ps at a repetition rate of 1 Hz. Upon calibration the EUV streak camera developed in this work will be used in future EUV development.
ID: 029049655; System requirements: World Wide Web browser and PDF reader.; Mode of access: World Wide Web.; Thesis (M.S.E.E.)--University of Central Florida, 2010.; Includes bibliographical references (p. 73-76).
M.S.E.E.
Masters
School of Electrical Engineering and Computer Science
Engineering and Computer Science

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Dissertations / Theses on the topic 'Ultraviolet spectroscopy'

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