Dissertations / Theses: 'X-ray spectroscopy'

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Juett, Adrienne Marie 1976. "X-ray spectroscopy of low-mass X-ray binaries." Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/28371.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 2004.
Includes bibliographical references (p. 125-144).
I present high-resolution X-ray grating spectroscopy of neutron stars in low-mass X-ray binaries (LMXBs) using instruments onboard the Chandra X-ray Observatory and the X-ray Multi-Mirror Mission (XMM-Newton). The first part of this thesis concentrates on results from the subset of LMXBs with orbital periods less than an hour, known as ultracompact binaries. Previous low-resolution X-ray spectra of four systems (4U 0614+091, 2S 0918-549, 4U 1543-624, and 4U 1850-087) all contain a broad residual near 0.7 keV which had been attributed to unresolved line emission. I show that this residual is due to an incorrect model of the intervening photoelectric absorption and can be accounted for by allowing a non-standard Ne/O abundance ratio in the intervening material. I propose that there is neon-rich material local to each binary and that the mass donor is a low-mass, neon-rich degenerate dwarf in an ultracompact binary. Follow-up spectroscopy of 2S 0918-549 and 4U 1543-624 with the High Energy Transmission Grating Spectrometer (HETGS) onboard Chandra and the Reflection Grating Spectrometer onboard XMM confirms the excess neutral neon absorption. Interestingly, the Ne/O ratio of 4U 1543-624 varies by a factor of three between the Chandra and XMMobservations, supporting the suggestion that some of the absorption originates local to the binaries. I also present X-ray spectroscopy of another ultracompact binary, the accretion-powered millisecond pulsar XTE J0929-314. No emission or absorption features are found in the high-resolution spectrum of this source, and the neutral absorption edge depths are consistent with the estimated interstellar absorption. The second part of this thesis uses LMXBs as probes of the interstellar medium (ISM).
(cont.) High-resolution X-ray studies of ISM absorption features can provide measurements of the relative abundances and ionization fractions of all the elements from carbon through iron. X- ray studies also probe the ISM on larger scales than is possible in the optical and ultraviolet wavebands. I present high-resolution spectroscopy of the oxygen K-shell ISM absorption edge in seven X-ray binaries using Chandra. The best-fit model consists of two absorption edges and five Gaussian absorption lines and can be explained by the recent theoretical calculations of K-shell absorption by neutral and ionized atomic oxygen. Significant oxygen features from dust or molecular components, suggested in previous studies, are not required by the Chandra spectra. These measurements also probe large-scale properties of the ISM, placing a limit on the velocity dispersion of the neutral lines of less than 200 km s-1 and constraining the interstellar ratio of O II/O I to approximately 0.1 and the ratio of O III/O I to less than 0.1.
by Adrienne Marie Juett.
Ph.D.

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Venturini, Federica. "Soft X-ray photoemission spectroscopy." Université Joseph Fourier (Grenoble), 2005. http://www.theses.fr/2005GRE10175.

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La motivation principale de cette thèse a été de déterminer les avantages et les inconvénients de l'utilisation de la spectroscopie de photoémission résolue en angle dans le domaine des rayons X mous. L'étude d'un système bien connu, Ag(001) nous permet de discuter plusieurs questions telles que le rôle de la quantité de mouvement du photon, la pertinence de l'approximation d'électron libre à l'état final, et le rôle des phonons. La polarisation de la lumière incidente a aussi été exploitée. En choisissant un tel système, nous avons aussi voulu comparer les résultats expérimentaux avec des spectres calculés de photoémission résolue en angle dans cette gamme d'énergie. Le comportement à basse température atypique des composés de Cérium est généralement imputé à l'effet Kondo. Des résultats originaux ont été obtenus en étudiant la bande de valence de trois composés monocristallins iso-structuraux de Cérium, CeCu2Ge2, CeNi2Ge2 et CeC02Ge2. La position du seuil d'absorption M5 du Cérium dans la bande d'énergie des rayons X mous est exploitée pour isoler la contribution 4f à ces spectres. De plus, l'utilisation de photons incidents d'énergie relativement élevée permet de minimiser les effets de surface. Les spectres de photoémission présentés dam cette thèse incluent des études de dépendance en température, des spectres à la résonance, des spectres résolus en angle ou bien intégrés angulairement. Les premiers sont en accord avec le modèle d'impureté unique d'Anderson, alors que les derniers suggèrent qu'il est important de prendre en compte le réseau cristallin
The main motivation behind this thesis has been to determine both the advantages and the disadvantages ofthe soft X-ray application of angle-resolved photoemission spectroscopy. The investigation of a weil known system, Ag(001), enables us to discuss several questions such as the role of the photon momentum, the applicability ofthe fiee-electron-like final state approximation and the role ofphonons. The polarisation of the incoming light has also been exploited. The choice of such a system also cornes from our des ire to compare the results with calculations of angle-resolved photoemission spectra in this energy range. The anomalous low temperature properties of Ce-based compounds are generally related to the Kondo effect. Original results have been obtained by investigating the valence band of three iso-structural single crystalline Ce compounds, CeCu2Ge2, CeNi2Ge2 and CeC02Ge2. The location of the Ce M5 absorption edge within the soft X-ray energy range is exploited in order to isolate the 4f contribution to the spectra. Added to this, the use of relatively high incoming photon energies allows minimising the surface contribution. Temperature dependent, resonant, angle-resolved and angle-integrated photoemission measurements have been performed. The former are in qualitative agreement with the single impurity Anderson model, whereas the latter suggest the importance of taking the lattice into account

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Krauss, Miriam Ilana. "X-ray spectroscopy of neutron star low-mass X-ray binaries." Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/45408.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 2007.
Includes bibliographical references (p. 133-150).
In this thesis, I present work spanning a variety of topics relating to neutron star lowmass X-ray binaries (LMXBs) and utilize spectral information from X-ray observations to further our understanding of these sources. First, I give an overview of important X- ray astrophysics relevant to the work I present in subsequent chapters, as well as information about the X-ray observatories from which I obtained my data. In the next three chapters, I consider spectra-both high- and low-resolution--of accretion-powered millisecond X-ray pulsars, a unique and relatively new class of objects. In addition to analysis of the pulsar XTE J1814-338, I compare a broader sample of pulsars with a sample of atoll sources in order to better understand why the latter class do not contain persistently pulsating neutron stars. In particular, I test the hypothesis that pulsations in the atoll sources are suppressed by a high-optical- depth scattering region. Using X-ray color-color diagrams to define a selection criterion based on spectral state, I analyze Rossi X-ray Timing Explorer (RXTE) spectra from all the sources, and use a Comptonization model to obtain measurements of their optical depths. I then discuss efforts to spatially resolve X-ray jets from the accretion-powered millisecond pulsar SAX J1808.4-3658 and the Z source XTE J1701-462. Each was observed by the Chandra X-ray Observatory to produce a high-spatial-resolution image. This work was motivated in part by my analysis of XTE J1814-338, which found an apparent excess of infrared flux which could be attributed to jet emission. Next, I discuss the measured temperatures of thermonuclear X-ray bursts. The detection of line features in these bursts, and hence from the surfaces of neutron stars, has been an important goal for high-resolution X-ray spectroscopy. A measurement of the wavelengths of identified line features would yield a measurement of the neutron star's gravitational redshift, which would help constrain current models for the neutron star equation of state.
(cont.) Although such a measurement has been made for one source, other searches have not been able to repeat this measurement. I consider the effects of burst temperature on the formation of discrete spectral features, using a large sample of bursts observed by the RXTE PCA. Finally, I present analysis of high-resolution Chandra HETG spectra of a sample of Galactic LMXBs. High-resolution spectra are able to resolve line features, such as the prominent Ne and O emission lines in the ultracompact X-ray binary 4U 1626-67. They also allow for more precise measurements of photoelectric absorption edges, which can otherwise hinder the determination of continuum spectral components, particularly in the lower-energy spectral regions.
by Miriam Ilana Krauss.
Ph.D.

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Såthe, Conny. "Applications of Soft X-Ray Spectroscopy." Doctoral thesis, Uppsala universitet, Mjukröntgenfysik, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-159369.

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Soft X-ray emission spectroscopy is an old experimental technique that has seen a strong revival since the advent of new high brilliance soft X-ray sources in the shape of synchrotrons. This thesis covers a range of applications where soft x-ray techniques have been applied. I have looked at fluorescence yield from doubly excited helium in field free conditions as well as in the presence of weak electric and magnetic fields. Using soft X-ray emission spectroscopy (SXES) I have explored scattering mechanisms in molecular systems. Quenching of symmetry breaking transitions by detuning of the excitation energy was observed in CO2. Bond-length dependence was seen for symmetry breaking transitions in a series of hydrocarbons. Dissociation dynamics was explored in OCS and HCl. I have also applied SXES to liquid water exploring the properties of hydrogen bonding. Buried layers of AlAs under 100 Å GaAs(100) was studied and thickness dependence and interface effects observed. The technique was also used to study the electronic structure of yttrium and vanadium hydrides. dd-excitations and accompanying spin flip excitations was observed in Cu M resonant x-ray Raman emission from Sr2CuO2Cl2.

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Costa, Felicissimo Viviane. "Infrared - X-ray pump probe spectroscopy." Licentiate thesis, Stockholm : Theoretical Chemistry, Royal Institute of Technology, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-324.

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Howell, Mark John. "Signal processing for X ray spectroscopy." Thesis, Bangor University, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.361173.

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Demir, Arif. "Spectroscopy of X-ray laser media." Thesis, University of Essex, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.361175.

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MOSTACCI, DOMIZIANO VALERIO. "X-RAY EMISSION FROM LASER-HEATED SPHERICAL PLASMAS." Diss., The University of Arizona, 1985. http://hdl.handle.net/10150/188093.

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A model has been developed for calculating x-ray line emission from spherical plasmas. The main features of this method are: (1) Plasma parameters are obtained from a one-dimensional Lagrangian hydrodynamics and heat flow code. (2) Multi-frequency groups: the line structure can be reproduced with the desired accuracy by adjusting the number of frequency groups. (3) Self consistent, time dependent excited level populations and radiation fluxes: the code starts with coronal populations, calculates the ensuing radiation flux and then recalculates the populations and so on, iterating until convergence is reached. (4) Goemetrical groups of rays groups by spherical impact parameters. (5) Line broadening due to ionic thermal agitation and Doppler shift due to the net plasma flow velocity. Inclusion of the flow velocity shift would be different without the multi-frequency group treatment. The method has been applied to an aluminum target, and the results are in good agreement with previous experimental work. The total energy, summed over all lines, as well as the line intensity ratios (which are a sensitive measure of agreement with experiment) were predicted with good accuracy. The pictures that would be seen by a pinhole camera are also calculated by the code.

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Rutherford, John (John Morton). "Imaging X-ray spectroscopy with micro-X and Chandra." Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/84183.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 2013.
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 245-258).
High spectral resolution observations of X-ray phenomena have the potential to uncover new physics. Currently, only point sources can be probed with high resolution spectra, using gratings. Extended objects like supernova remnants cannot be dispersed, leaving the dense forest of emission lines blended by the moderate resolution of modern instruments. In the first half of this thesis, I undertake two investigations of the supernova remnant Cassiopeia A using the flagship X-ray observatory, Chandra. The first study combines the spatial resolution of the ACIS instrument with the spectral resolution of the dispersive HETG to investigate the evolution of ejecta knots. The second improves on statistical limits of radioactive ejecta, and simulates what higher resolution instruments may observe. Micro-X, a new high resolution X-ray telescope, is the focus of the second half. I detail the commissioning of this novel sounding rocket payload, which uses a focal plane of micro-calorimeters to achieve high spectral resolution in each pixel. The flight hardware is in a final state of testing and integration before the launch, which is anticipated in 2014.
by John Rutherford.
Ph.D.

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McCluskey, Philip James. "X-ray emission and x-ray photoelectron spectroscopy of alloy and catalyst surfaces." Thesis, Queen Mary, University of London, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.264926.

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Chan, Paul Ka-Hang. "Analytical applications of X-Ray photoelectron spectroscopy." Thesis, University of British Columbia, 1987. http://hdl.handle.net/2429/26186.

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The surface-specific analytical technique of X-ray photoelectron spectroscopy (XPS) is described, and was used to study various geochemical materials and organic compounds. Variation of surface pyrite density with coal particle size (53-250/µm) in a typical Canadian coal (Minto) provided some interesting data- it is very likely that as coal is crushed, one eventually reaches a particle size where the surface pyrite/carbon ratio maximizes. It is this parameter that is examined here, and correlations were found between (i) surface pyrite concentration,(ii) surface pyrite/sulfate ratio, and (iii) oxidized and non-oxidized sulfur with particle size. This is information which should find useful application in coal cleaning technology. For non-oxidized coal, we find the area of exposed pyrite on the coal surface is approximately inversely proportional to coal particle radius. However, for oxidized coal the appearance of curves depends on the oxidation times, but there is a particle size which exhibits maximum surface pyrite relative to 1/radius, corresponding to the intercept point of the two linear segments (low and higher values of 1/R) for the non-oxidized coal (fig. 3.9), and which is evidently that we will call the "characteristic" size of constituent pyrite. XPS 2p₃/₂ sulfur peaks from major sulfur constituents other than sulfate in sediment recovered from Mahoney Lake (south-central British Columbia, Canada) show a surprisingly periodic variation in sulfur 2p₃/₂ binding energy (BE), and hence molecular structure, with sediment age. The pattern ceases at a core depth of about 3.2 meters, where a major deposit of fine sandy sediment occurs just below ash deposition (2.6m) from a major eruption of Mount Mazama, Oregon, approximately 6500 year ago, which led to the formation of Crater Lake. Sedimental sulfur exists mainly as sulfate; however, there is a pronounced increase in amount of the lower BE sulfur species relative to sulfate toward lower depths. The "reduced" species also shows a trend towards slightly higher oxidation level at lower depths. We are able to suggest the probable chemical forms in which the sulfur species exist, which is of interest to biologists working on sulfur transformation studies in lakes. BE' s for nitrogen Is and sulfur 2p₃/₂ in the metal chelates of dibenzyldithiocarbamic acid M(DBDTC)n for n=2, M=Cu(II) and Zn(II), and for n=3, M=Bi(III), have been measured. The nature of the spectral peaks and core BE's indicates that the nitrogen atom in the DBDTC is not intramolecularly bound with the metal as had been previously suggested. The relatively high BE's for the nitrogen Is orbitals indicate planar geometry for the coordinated ligands, and the form [formula omitted] to reasonably represent their structure, which agrees with previous infrared studies.
Science, Faculty of
Chemistry, Department of
Graduate

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Pappa, Anastasia. "X-ray spectroscopy of active galactic nuclei." Thesis, University of Leicester, 2001. http://hdl.handle.net/2381/30643.

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This thesis was triggered by the question what is the nature of the sources producing the bulk of the X-ray background at hard energies. Of course the pre-Chandra missions did not allow any definite answer to this question. Therefore the approach adopted in this work is to examine whether candidate populations of objects could contribute to the X-ray background significantly. This was achieved by studying spectroscopically a variety of objects. To be more specific, in Chapter 3 it was examined whether broad line quasars, which produce the bulk of the X-ray background at soft energies, contribute significantly to the hard X-ray background as well. In Chapter 4 the X-ray properties of a sample of Seyfert 2 galaxies were examined. The results were examined in the light of the current X-ray background synthesis models. This study revealed two "odd" Seyfert 2 galaxies (NGC3147 and NGC4698). Odd, in the sense that although both galaxies are classified as Seyfert 2 in the optical, their X-ray data do not show evidence for absorption above the Galactic. Possible scenarios explaining the emission from the two galaxies are examined in Chapter 5. Chapter 6 considers the spectral properties of the Ultraluminous infrared galaxy 'The Superantennae'. In Chapter 7 a study of the composite galaxy Mrk609 is presented. The composite galaxies resemble the narrow-line X-ray galaxies (NLXGs) detected in large numbers in deep ROSAT surveys. Thus the study of the spectra of composite galaxies provides an indirect insight into the spectra of the NLXGs. Finally Chapter 8 summarises the results of this work.

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Shiwai, B. A. "X-ray absorption spectroscopy of dense plasmas." Thesis, University of Essex, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.235244.

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Tasker, G. William. "X-ray photoelectron spectroscopy of silicate glasses." Thesis, Massachusetts Institute of Technology, 1987. http://hdl.handle.net/1721.1/49574.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 1987.
MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE.
Vita.
Includes bibliographies.
by G. William Tasker.
Ph.D.

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Plant, Daniel. "X-ray spectroscopy of accreting black holes." Thesis, University of Southampton, 2014. https://eprints.soton.ac.uk/371747/.

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Measuring black hole spin has become a key topic in astrophysics, and recent focus on the spin powering of jets in X-ray binaries has heightened the need for accurate measurements of spin. However, the effects of spin are subtle, and are only imprinted on emission from very close to the black hole. This is revealed since the black hole spin defines the radius of the last stable orbit of the accretion disc, which is smaller for larger spin. Recent advances in X-ray observatories and spectroscopic techniques have enabled spin estimates for a number of black holes in X-ray binaries,but the accuracy of these methods, and the link between spin and jet power,have become very controversial subjects. In this thesis I address the former of these problems through X-ray reflection, which is one of two leading X-ray spectroscopic methods to measure black hole spin (the other being the ‘continuum’ method). Firstly, I investigate the systematic uncertainties associated with the X-ray reflection technique, and display how model degeneracies can severely affect the determination of spin. After establishing these potential flaws I then performed a systematic study of X-ray reflection during four hard state observations of the black hole GX 339−4, and show that the relativistic effects vary significantly over two orders of magnitude in luminosity. I show that this requires the accretion disc to be substantially truncated from the last stable orbit that is used to measure spin, thus rendering spin estimates impossible in the hard state. Following this I analyse over 500 archival observations of the same source with the Rossi Timing X-ray Explorer. Whilst these data cannot directly measure the inner disc radius, they allow a quantitative investigation of how X-ray reflection and the power-law co-evolve. Since the latter gives rise to the former, this allows changes in the accretion geometry to be revealed, which I show to be consistent with a truncated accretion disc in the hard state, and a gradual collapse of the corona in the soft state. Finally, I present three recent observations of GX 339−4 in the hard state with XMM-Newton, which allow an unprecedented simultaneous constraint on the inner accretion disc radius via the reflection and continuum methods. The two techniques agree, and present further compelling evidence for accretion disc truncation in the hard state.

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Pan, Lei. "Development of perovskite for X-ray detection and gamma-ray spectroscopy." The Ohio State University, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=osu161886103349645.

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Costa, Felicissimo Viviane. "Principles of Infrared - X-ray Pump-probe Spectroscopy." Doctoral thesis, KTH, School of Biotechnology (BIO), 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4245.

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The present thesis concerns theoretical studies of molecular interactions investigated by infrared and X-ray spectroscopic techniques, with emphasis on using these two techniques combined in pump-probe experiments. Four main types of studies are addressed: the use of near-edge X-ray absorption fine structure spectra (NEXAFS) to manifest through-bond and through-space interactions; the role of hydrogen bonding in the formation of X-ray photoelectron spectra as evidenced by simulations of the water dimer; the development of theory, with sample applications, for infrared X-ray pump-probe spectroscopy; and molecular dynamics simulations of light-induced fragmentation of water clusters.

Ab initio calculations indicate that NEXAFS spectra give direct information about the through-bond and through-space interactions between vacant non-conjugated π* orbitals. It is found out that the X-ray photoelectron spectrum of the water dimer differs dramatically from the monomer spectrum in that two bands are observed, separated by the chemically shifted ionization potentials of the donor and the acceptor. The hydrogen bond is responsible for the anomalously strong broadening of these two bands. The studies show that X-ray core electron ionization of the water dimer driven by an infrared field is a proper technique to prove the proton transfered state contrary to conventional X-ray photoelectron spectroscopy.

The physical aspects of the proposed new X-ray spectroscopic method - phase sensitive Infrared - X-Ray Pump-Probe Spectroscopy - are examined in detail using the wave packet technique in three applications; the NO molecule and the dynamics of proton transfer in core ionized water dimer and glyoxalmonoxime. It is found out that the phase of the infrared pump field strongly influences the trajectory of the nuclear wave packet on the ground state potential, which results in a phase dependence of the X-ray pump-probe spectra. A proper choice of the delay time of the X-ray pulse allows the direct observation of the X-ray transition in the proton transfered well of the core excited potential. It is found out that the glyoxalmonoxime molecule possesses an important feature; proton transfer accompanied by core hole hopping. Special attention is paid to the quantum control of the populations of vibrational level which is of crucial importance to shape the wave packet of desirable size.

The wave packet technique becomes computationally very expensive when the number of nuclear degrees of freedom is large. Molecular dynamics is used instead in studies of light-induced nuclear kinetics in the water hexamer cluster. We predict a novel mechanism of the mechanical action of light on atoms and molecules. This mechanism is based on the rectification of the Lorentz force, which gives a unique opportunity of direct site selective mechanical action of light on atoms and molecules inside large systems like clusters or biomolecules.

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Reeves, James. "X-ray spectroscopy of quasars observed with ASCA." Thesis, University of Leicester, 1999. http://hdl.handle.net/2381/30625.

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This thesis presents results from a sample of quasars observed with the X-ray astronomy satellite ASCA. The ASCA sample consists of 68 quasars, 35 of which are radio-loud and 33 radio-quiet, covering a range of quasar redshift and luminosity. Differences were found between the radio-loud and radio-quiet quasars; the radio-loud quasars tend to have harder (or flatter) X-ray spectra (~1.5-1.6) and are more X-ray luminous, compared to the softer (~1.9), lower luminosity, radio-quiet quasars. In addition it is found that the line or reflection component observed in some of the radio-quiet quasars is diminished (or absent) in the radio-loud quasars. These observations are consistent with a Doppler-boosted component from a relativistic jet being present in the radio-loud quasars, but not the radio-quiet quasars. Evidence for reprocessing of the primary X-ray emission is also seen in several quasars. Iron line and reflection features are found predominantly in the radio-quiet quasars. The rest energy and ionisation state of the line emission was found to increase towards the higher luminosity quasars; this was interpreted in terms of the increased ionisation of the inner accretion disk with luminosity and accretion rate. Indeed the highest luminosity radio-quiet quasars show no line or disk reflection features, the result being a featureless power-law continuum, which can be explained if the quasars accrete near the Eddington limit. X-ray absorption is also found in several of the quasars; a trend is found for the absorber column density to increase with quasar redshift. When corrected for calibration effects and local origins, this absorbing material must either reside locally to the quasars or originate from line-of-sight matter.

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Soman, Matthew. "High-resolution detectors for soft X-ray spectroscopy." Thesis, Open University, 2014. http://oro.open.ac.uk/42020/.

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Resonant Inelastic X-ray Scattering (RIXS) is a modern soft X-ray spectroscopy technique used to investigate the structure of and excitations in materials. It requires high resolution spectrometers and a brilliant, tunable, X-ray source and therefore is carried out at spectrometers such as SAXES at the Swiss Light Source Light, a synchrotron at the Paul Scherrer Institut. SAXES uses a grating to disperse X-rays scattered from a sample across a position sensitive detector, a Charge-Coupled Device (CCD). It has been recognised that the spatial resolution of the CCD currently limits the spectrometer resolution and therefore the investigations described in this thesis focus on developing and testing methods of improving the detector resolution. Whilst this thesis addresses improving the resolution of the detector at SAXES specifically, the methods and results are applicable to other applications requiring high spatial resolution soft X-ray detection. After an introduction, Chapters 2 and 3 describe the importance of RIXS, operation of SAXES and background of soft X-ray detection in CCDs. A comparison of models that describe charge spreading in a CCD is in Chapter 4, and the best model is implemented in a simulation package that generates populations of soft X-ray events. Chapter 5 explores the resolution improvements possible through applying centroid algorithms to simulated X-ray events, and Chapter 6 begins by describing experimental work undertaken to verify simulation results. Due to the limitations of applying centroiding algorithms to the current SAXES camera, a small-area Electron Multiplying CCD (EM-CCD) is experimentally tested (Chapter 7). Results with the EM-CCD proved positive, therefore in Chapter 8 the spatial resolution achievable with a large area EM-CCD is verified for a future SAXES camera upgrade. Due to the successful results presented in this thesis, negotiations to develop a new camera system for SAXES are underway, and interest from other RIXS beamlines in the community may lead to the work also being applied elsewhere. The detection of soft X-rays with high spatial resolution is applicable to other future CCD and EM-CCD instruments, such as astronomical X-ray observatories.

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Börjeson, Charlie, and Julia Cohen. "X-ray Spectroscopy of Distant Active Galactic Nuclei." Thesis, KTH, Skolan för teknikvetenskap (SCI), 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-210847.

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The physical structure and behaviour of stars have been studied extensively throughout centuries.In contrast, the existence of objects now known as Active Galaxies has only been established since a couple of decades. The nucleus of such an object radiates an extraordinary amount of light across the electromagnetic spectrum, sometimes outshining the rest of the galaxy. However, since many Active Galactic Nuclei (AGNs) live in the distant universe, they are difficult to observe even with the advanced instruments of the 21st century and plenty of effort is being put into this field by astronomers wishing to understand the inner structure of these nuclei. One survey was started in 1999 by the 2002 Nobel Prize winner Riccardo Giacconi, where the Chandra telescope made several observations in the sky direction called Chandra Deep Field South. A separate pencil-beam survey of ~700 arcmin2 in this area has been performed by the telescope XMM-Newton in the ranges 2-10 keV and 5-10 keV, where the number of X-ray sources classified as AGNs is currently estimated to be 339 and 137 for each energy range, respectively. We studied two sources amongst the most brilliant in the surveys to explore their X-ray spectra and their X-ray variability and found that one is strongly absorbed in the line of sight while the other does not display any absorption. Their variability properties are also different, since the non-absorbed source displays variability behaviour similar to well known nearby AGNs in the literature.The study is limited to two intrinsically different AGNs finding that they differ not only in the spectral domain but also in the time domain.

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Costa, Felicíssimo Viviane. "Principles of infrared - x-ray pump-probe spectroscopy /." Stockholm : Royal Insitute of Technology, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4245.

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Kashtanov, Stepan. "Theoretical modeling of X-ray spectroscopy of liquids /." Stockholm, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-187.

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McEntaffer, Randall L. "Soft X-ray spectroscopy of the Cygnus Loop." Connect to online resource, 2007. 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:3284491.

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Rainnie, J. A. "X-ray spectroscopy of tokamak and solar plasmas." Thesis, Queen's University Belfast, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.396222.

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Carter, James Andrew. "Lunar surface composition from X-ray fluorescence spectroscopy." Thesis, Aberystwyth University, 2013. http://hdl.handle.net/2160/bda827d4-7dc7-46d5-b92a-ff18dc37d7a0.

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What is the composition of the surface of the Moon? This investigation aims to map the abundances of some of the main rock-forming elements over the surface of the Moon. Accurately determining the magnesium, aluminium and silicon abundances would have great advantages when performing geological and geochemical studies of the Earth-Moon system, helping to answer questions about its formation and evolution. This thesis uses data from the Chandrayaan-1 X-ray Spectrometer (C1XS) instrument on Chandryanaan-1, a high quality instrument that nevertheless flew in one of the lowest solar minima on record. Modelling software is described and written to predict the performance of an orbiting X-ray spectrometer (XRS) under different conditions, a vital task for premission planning and post-mission analysis. Surface factors, such as compositional modification by crater rays and the enhancement of X-ray returns by volatile sodium, are modelled to assess their effects on XRS signals. The C1XS data is processed using a data pipeline, and inspected and analysed. After some post-pipeline processing maps are produced, first elemental line intensity ratio maps, and then absolute elemental abundance maps. These are produced for the southern nearside lunar highlands, and are then compared to previous datasets and ground truth.

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Smila-Castro, Ornella. "X-ray absorption spectroscopy studies of electrochemical processes." Thesis, University of Birmingham, 2012. http://etheses.bham.ac.uk//id/eprint/3766/.

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Electron transfer is a key part of many chemical, biological and physical processes, that is commonly studied by electrochemical methods, which give insight into reaction mechanisms but no structural information. It is necessary to combine electroanalysis with another technique to gain essential knowledge of metal-ligand bond length and oxidation states. X-ray absorption spectroscopy (XAS) can provide these data for species in dilute solution and, if combined with electrochemistry, could potentially provide powerful insight into electron transfer reactions. This dissertation describes the development and application of techniques for the study of electrochemical intermediates by XAS. Chapters 2 and 3 introduce the theory and practice of electrochemistry and spectroscopy with emphasis on XAS. Chapter 4 describes the development of variable-temperature spectroelectrolysis cells for the study of electrochemical intermediates. In Chapter 5, the electrochemical behaviour of Cp\( \ast \)Rh(CO)\(_2\), is investigated as an organometallic compound representative of the redox chemistry studied in this thesis. Chapter 6 describes a new approach to the study of electrochemical intermediates in which a miniature electrolysis cell is combined with a microdispenser so that electrochemical intermediates can be generated and then dispensed, quenched at low temperature prior to study by XAS. Chapter 7 contains final conclusions.

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Lee, Jonathan Richard Ian. "X-ray absorption spectroscopy studies of electrode surfaces." Thesis, University of Cambridge, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.615888.

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Chadwick, Alan V., and Shelley L. P. Savin. "X-Ray absorption spectroscopy measurements on nanocrystalline materials." Universitätsbibliothek Leipzig, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-186608.

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29

Dunn, James. "High resolution X-ray spectroscopy of laboratory sources." Thesis, University of Leicester, 1990. http://hdl.handle.net/2381/35870.

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A detailed programme of research is presented to design, build and operate a high resolution h?hz5000 curved crystal Johann-type x-ray spectrometer for the waveband below 13A. The spectrometer is used to observe line emission features from different laboratory x-ray sources. Characteristics of the Johann geometry are described with emphasis given to the properties of sensitivity, dispersion, resolving power and waveband. The tolerance of the instrumental parameters is defined for successful high spectral resolution operation. The key feature of the spectrometer is the unique crystal bending device which can generate a high quality cylindrical curvature of radius R=150?5000mm. The crystal focusing alignment and testing procedures are evaluated. Choice of crystals suitable for the observation programme is discussed together with analysis techniques for interpretation of the x-ray spectral line profiles. The instrument is optimised for time-integrated and time-resolved ion temperature measurements of UKAELA DITE Tokamak at the Culham Fusion Laboratory. X-ray line emission results from medium Z He-like and H-like impurity ions are presented for different plasma conditions. Density sensitive He-like and Li-like Aluminium ion satellite emission features are studied for intense transient laser produced plasmas at the Central Laser Facility, SERC Rutherford Appleton Laboratory. The peak plasma electron density of 0.1 time solid density is estimated from these line intensity ratios and is in good agreement with Stark line width measurements. X-ray emission from beam-foil interactions is observed on the Folded Tandem accelerator of the Nuclear Physics Department, Oxford University. The proposed improvement in the intrinsic spectral line broadening due to the accelerator is investigated by high resolution axial beam measurements of the He-like Silicon and H-like Neon n=2 transitions. The Lyman-a intensity ?-ratio and wavelength separation ?hFS is studied for the fine-structure of Hydrogenic Neon, Magnesium, Aluminium and Silicon. The fine-structure separation is compared with the Dirac theory and other experimental data, while the possible mechanisms giving rise to the non-statistical value of the ?-ratio are analysed.

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30

Hobbs, Sarah. "Development of resonant inelastic X-ray scattering spectroscopy." Thesis, University of Southampton, 2012. https://eprints.soton.ac.uk/349475/.

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This research focuses on the development of Resonant Inelastic X-ray Scattering spectroscopy (RIXS) as a tool in homogeneous catalysis by looking at 3d transition metal compounds and specifically Cr(salen) epoxidation catalysts. Previous studies have demonstrated the sensitivity of transition metal K-edge X-ray absorption pre-edge and edge features to their chemical environment, but the exact origins are unassigned. The aim of this study is to bring together a collection of complementary, and some novel, X-ray techniques to assign these features and obtain more detailed structural and electronic information on the systems under investigation. Novel high energy resolution data on transition metal complexes have been obtained and the pre-edge region has been simulated with the FEFF9 multiple scattering code. The increase in spectral structure compared to normal XANES allows for a more detailed analysis and as such, provides detailed insights in the electronic properties. L-edge XAS data obtained using soft X-rays enabled the determination of crystal field parameters, which were compared with other X-ray (RIXS) and optical absorption techniques. The novel RIXS experiments provide L and K-edge spectra unaffected by lifetime broadening or background from the main absorption edge. 2D images of X-ray emission as a function of absorption are obtained, revealing the relationship between them and providing direct and detailed information on the presence and position of molecular orbitals. These 1s2p RIXS experiments make use of hard X-rays enabling in-situ experiments, which are important in the field of catalysis, making it a promising tool to monitor the changing electronics of the metal centre as well as ligand coordination during the catalytic process. Whereas the electronic differences on the Cr metal as a function of salen ligand are not revealed by the current RIXS experiments, which is likely due to resolution issues, new preliminary insights in the different catalytic Cr intermediates of the epoxidation reaction have been obtained.

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Chadwick, Alan V., and Shelley L. P. Savin. "X-Ray absorption spectroscopy measurements on nanocrystalline materials." Diffusion fundamentals 12 (2010) 17, 2010. https://ul.qucosa.de/id/qucosa%3A12819.

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32

Ehrman, James D. "X-Ray Photoelectron Spectroscopy Studies of Orthopedic Materials." University of Akron / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=akron1248115447.

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Müller, Oliver [Verfasser]. "Hard X-ray Synchrotron Beamline Instrumentation for Millisecond Quick Extended X-ray Absorption Spectroscopy / Oliver Müller." Wuppertal : Universitätsbibliothek Wuppertal, 2016. http://d-nb.info/1120339022/34.

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34

Varney, Andrew John. "Development of x-ray spectrometers and x-ray spectroscopy for the Oxford electron beam ion trap." Thesis, University of Oxford, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.282196.

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35

Unuigbe, David Moweme. "Characterisation of silicon nanoparticles produced by mechanical attrition using scanning electron microscopy, energy dispersive X-ray spectroscopy and X-ray photoemission spectroscopy." Master's thesis, University of Cape Town, 2012. http://hdl.handle.net/11427/12105.

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Includes abstract.
Includes bibliographical references.
The establishment of printing technologies, using nanoparticle based inks, promises inexpensive manufacture of electronic devices. However, to produce working devices, nanoparticles have to meet requirements on size, shape, and composition. In the application of silicon nanoparticles in electronics, it is important that a network of interconnecting particles is formed through which charge transport can take place. Of further importance is that there is an absence of surface oxide in order to maintain a direct silicon-silicon connection within the network. In this work, cheap and scalable production of silicon nanoparticles is achieved efficiently with a top-down process of mechanical attrition by high energy milling.

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36

Fuchs, Oliver. "Soft x-ray spectroscopy of organic molecules and liquids." Doctoral thesis, kostenfrei, 2009. http://www.opus-bayern.de/uni-wuerzburg/volltexte/2009/3705/.

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37

Carr, James. "Error analysis of X-ray photon correlation spectroscopy measurements." Thesis, McGill University, 2013. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=117183.

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The use of a theory to extract parameters from experimental data requires proper understanding of the statistical variation. Furthermore, the improvement of any experimental technique requires a sound understanding of the sources of error and an accurate model of how experimental parameters effect signal strength and noise. The second order intensity-intensity correlation function is the standard measured quantity in dynamic light scattering and x-ray photon correlation spectroscopy (XPCS) experiments. In this thesis we compare the measured variances of the correlation function to a model based on the statistics of dynamic light scattering. Agreement between the dynamic light scattering model and the x-ray photon correlation spectroscopy data is shown. XPCS experiments are typically conducted with low photon flux and are used to study long time constants. To achieve sufficient statistics area detectors are used. We show that there are appreciable correlations between near neighbour pixels. These correlations reveal important features that must be included to accurately draw conclusions from XPCS experiments.
L'utilisation d'une théorie pour extraire des paramètres depuis des données expérimentales nécessite une compréhension des variations statistiques. De plus, l'amélioration d'une technique expérimentale repose sur la compréhension des sources d'erreurs and d'un modèle précis de l'effet des paramètres expérimentaux sur le signal et le bruit. La fonction de corrélation intensité-intensité de deuxième ordre est une quantité de mesure standardisée pour les expériences de diffusion de lumière dynamique et de spectroscopie de corrélation de photons en rayons X (X-ray Photon Correlation Spectroscopy, XPCS). Dans cette thèse, nous comparons les variances mesurées de la fonction de corrélation à un modèle basé sur les statistiques de diffusion de lumière dynamique. Nous démontrons l'accord entre le modèle de diffusion de lumière dynamique et les données XPCS. Les expériences XPCS sont en général effectuées avec un faible flux de photons et sont utilisées pourétudier les constantes à long terme. Pour atteindre des statistiques susantes, de détecteurs à résolution spatiale sont utilisés. Nous montrons l'existence de corrélations entre pixels voisins. Ces corrélations révèlent d'importantes caractéristiques qui doivent tre inclues afin de tirer des conclusions précises des expériences XPCS.

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38

Freeman, Adam Alexander. "Magnetic X-ray spectroscopy studies of dilute magnetic semiconductors." Thesis, University of Nottingham, 2009. http://eprints.nottingham.ac.uk/10839/.

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Dilute magnetic semiconductors are an important family of materials that have many potential applications in spintronics; (Ga,Mn)As, (In,Ga,Mn)As and (Ga,Mn)N are of major interest. This thesis investigates dierent aspects of these, using the synchrotron radiation techniques of x-ray magnetic circular dichroism (XMCD) and x-ray magnetic linear dichroism (XMLD), supported by superconducting quantum interference device (SQUID) magnetometry and magnetotransport measurements. A large anisotropic XMLD signal is observed for the Mn L-edge in (Ga,Mn)As. In unannealed (Ga,Mn)As, an apparently reduced Mn magnetic moment is commonly observed. It is thought to be related to compensation of both carriers and magnetic moment, caused by interstitial Mn. This issue is investigated using combined data from XMCD, XMLD and SQUID magnetometry. The findings suggest that substitutional and interstitial Mn form `non-magnetic' pairs which do not have a preferred spin orientation. (Ga,Mn)N is studied by x-ray absorption and field-dependent XMCD at the Mn L-edge. Two distinct Mn congurations are identified: Mn2+ is prevalent towards the surface with nearly paramagnetic behaviour, while a weakly ferromagnetic Mn2+/Mn3+ mixed valence exists within the bulk. The weak ferromagnetism, often observed in (Ga,Mn)N, is attributed to coupling between the impurities by the double exchange mechanism. Finally, XMCD is used to measure the orbital polarization of As 4p states of (III,Mn)As materials. These states correspond to those of the holes involved in the itinerant exchange interaction in ferromagnetic semiconductors. The coupling between the localized d states of the magnetic impurities and the valence band p states of the host is demonstrated by an anisotropy in the orbital moment of these states. This is experimental confirmation of the origin of the magnetocrystalline anisotropy in dilute magnetic semiconductors.

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39

Fairbrother, P. J. "Thermal diffuse scattering in energy-dispersive x-ray spectroscopy." Thesis, University of Exeter, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.232967.

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40

Nave, Gillian. "Soft X-ray spectroscopy of gas-puff z-pinch." Thesis, Imperial College London, 1986. http://hdl.handle.net/10044/1/38116.

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41

Avara, Mark J. "Precision X-ray spectroscopy of 3C 273 jet knots." Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/44464.

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Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Physics, 2008.
Includes bibliographical references (p. 55-56).
We present results from precision X-ray spectroscopy using high-resolution ([delta lambda] = 0.01A) spectra of 3C 273 jet knots extracted from eight observations made using Chandra in conjunction with the HETGS. Using these spectra we searched for narrow emission line candidates and, based on significance values calculated for the observed photon counts in each bin of the spectrum of the entire jet, we selected three possible emission candidates and attempted to match these with known highly emissive X-ray emission lines. From this calculation we found the temperature of the X-ray emitting plasma to be 106.8 K, the bulk velocity of the knots to be 0.78 times the speed of light, and the electron density in the jet to be 0.043+/-.007 .009cm-3.
by Mark J. Avara.
S.B.

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42

Chowanietz, Eric Gunther. "Advances in CCDs for X-ray imaging and spectroscopy." Thesis, University of Leicester, 1986. http://hdl.handle.net/2381/35856.

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A review of X-ray telescope focal-plane instrumentation is given. The architectures and operating principles of contemporary charge-coupled device (CCD) imagers are discussed. The fabrication of CCDs manufactured by EEV Ltd. is described. An overview of a slow-scan CCD evaluation system is given and the design, construction and operation of a microcomputer controlled programmable CCD readout sequencer is detailed. The technique of on-chip pixel binning is discussed. CCD noise sources and noise measurement techniques are reviewed and constructional details of a low noise analogue CCD signal processor are presented. A description of CCD data processing and image display software is given. The results of X-ray efficiency and energy resolution measurements on standard and specially developed deep-depletion CCDs are presented and accounted for. It is shown that deep-depletion devices can be fabricated to offer energy resolution equal with that of standard devices, together with superior detection efficiencies. Both device types are shown to give spectral resolution comparable with that obtained from other silicon-based detectors. Aspects of CCD operation in the space environment are considered and the relevance of this work to the development of CCD instrumentation for the European Space Agency's XMM satellite is assessed. In conclusion, the important characteristics of standard and deep-depletion CCDs are noted and areas thought to require further investigation are highlighted.

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Hicks, Leon James. "X-ray spectroscopy and electron microscopy of planetary materials." Thesis, University of Leicester, 2015. http://hdl.handle.net/2381/31986.

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The work described in this thesis features the study of planetary materials, including nakhlite martian meteorites, comet 81P/Wild2 grains, and asteroid Itokawa 25143 particles, using various electron microscopy techniques and X-ray spectroscopy. Transmission electron microscopy (TEM), Fe-K X-ray absorption spectroscopy (XAS) and in-situ Transmission X-ray Diffraction (XRD) have been used to determine the structure, ferric content and stoichiometry in the secondary phase mineral assemblages of the nakhlites. By measuring the energy position of the Fe-K XANES 1s→3d pre-edge transition centroid, the Fe3+-rich nature of these minerals has been shown. Analyses of the crystalline phyllosilicates in Lafayette found trioctahedral ferric saponite with a 2:1 T-O-T lattice structure and d001-spacings of 0.96 nm, as well as Fe-serpentine with a 1:1 T-O structure and d001-spacings of 0.7 nm. A ferric poorly crystalline or amorphous gel of similar composition to the phyllosilicates was found as fracture fills throughout the other nakhlites. XRD and Fe-K XAS also allow the mineralogical identification of comet Wild2 terminal grains. The terminal grains of Tracks #170 and #176 are Fe-metal, with hematite subgrain material in #170. The terminal grain of #170 also includes Cr-bearing silicate, similar to the Cr-bearing terminal grain of Track #177. Olivine was found amongst the terminal grains of Track #178 alongside magnetites. The presence of magnetite is consistent with low temperature water-rock interaction similar to a carbonaceous chondrite matrix. XAS has also been used to study Itokawa particles, finding ferrous olivines and pyroxenes, as well as studying other metals and Ni-bearing phases. Comparisons with the Tuxtuac meteorite showed the similarity of Itokawa particles to that of LL5 and LL6 chondrite materials. Measuring Fe-K XAS and XRD has proved to be an effective and non-destructive method for mineralogical characterisation of planetary samples, and determining the oxidation state of Fe-silicates, especially on a micron scale. These will be essential techniques for future sample return missions and meteorite finds.

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Rogers, Thomas D. "Suborbital Soft X-Ray Spectroscopy with Gaseous Electron Multipliers." Thesis, University of Colorado at Boulder, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=10151140.

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This thesis consists of the design, fabrication, and launch of a sounding rocket payload to observe the spectrum of the soft X-ray emission (0.1-1 keV) from the Cygnus Loop supernova remnant. This instrument, designated the Off-plane Grating Rocket for Extended Source Spectroscopy (OGRESS), was launched from White Sands Missile Range on May 2nd, 2015. The X-ray spectrograph incorporated a wire-grid focuser feeding an array of gratings in the extreme off-plane mount which dispersed the spectrum onto Gaseous Electron Multiplier (GEM) detectors. The gain characteristics of OGRESS's GEM detectors were fully characterized with respect to applied voltage and internal gas pressure, allowing operational settings to be optimized. The GEMs were optimized to operate below laboratory atmospheric pressure, allowing lower applied voltages, thus reducing the risk of both electrical arcing and tearing of the thin detector windows. The instrument recorded 388 seconds of data and found highly uniform count distributions over both detector faces, in sharp contrast to the expected thermal line spectrum. This signal is attributed to X-ray fluorescence lines generated inside the spectrograph. The radiation is produced when thermal ionospheric particles are accelerated into the interior walls of the spectrograph by the high voltages of the detector windows. A fluorescence model was found to fit the flight data better than modeled supernova spectra. Post-flight testing and analysis revealed that electrons produce distinct signal on the detectors which can also be successfully modeled as fluorescence emission.

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Rosen, Gregory Todd. "X-ray Absorption Fine Spectroscopy of Amorphous Selenium Nanowires." Ohio University Honors Tutorial College / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=ouhonors1294448896.

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46

Feng, Yejun. "Exciton spectroscopy using non-resonant x-ray Raman scattering /." Thesis, Connect to this title online; UW restricted, 2003. http://hdl.handle.net/1773/9642.

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47

Chaudhry, M. A. "Electron and X-ray spectroscopy of electron-atom collisions." Thesis, University of Stirling, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.379507.

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Ballhausen, Ralf [Verfasser], Jörn [Akademischer Betreuer] Wilms, Jörn [Gutachter] Wilms, and Randall [Gutachter] Smith. "X-ray spectroscopy of X-ray binaries / Ralf Ballhausen ; Gutachter: Jörn Wilms, Randall Smith ; Betreuer: Jörn Wilms." Erlangen : Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 2021. http://d-nb.info/1229695214/34.

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Li, Kwan-lok, and 李君樂. "Study of x-ray supernovae and supersoft/quasisoft x-ray sources with an automated source search program." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2011. http://hub.hku.hk/bib/B46084125.

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Pestehe, Sayyed Jalal. "Spectroscopic studies of X-ray laser media." Thesis, University of York, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.369284.

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