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Dissertations / Theses on the topic 'IONIZATON'

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Published: 4 June 2021
Last updated: 4 February 2022

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1

Zhi, Qiu. "Study of Ionizaton of Quantum Systems with Delta Potentials in Damped and Undamped Time Periodic Fields." The Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=osu1250019795.

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2

Love, Natalie Anne. "Studies of electron ionization." Thesis, University College London (University of London), 2005. http://discovery.ucl.ac.uk/1444953/.

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This thesis presents the results of experimental investigations to determine the electron ionization cross-sections of gases used in plasma etching processes. The small molecules studied include boron trichloride (BCI3), nitrous oxide (N20), sulphur hexafluoride (SF6) and acetylene (C2H2). The knowledge of accurate electron ionization cross-sections is essential for the modelling and optimization of plasmas used in industry and for the purposes of atmospheric modelling. It is therefore surprising that despite the widespread industrial use of these small molecules there have been few investigations of their ionization. It is the lack of available electron ionization cross-section data that provides the motivation for the investigations detailed in this thesis. The formation and dissociation of singly charged (monocations), doubly charged (dications) and triply charged molecular ions (trications) are studied using pulsed electron ionization (30-200 eV) coupled with time-of-flight (TOF) mass spectrometry and a two-dimensional (2D) ion coincidence technique. The experimental technique and data analysis procedures adopted allow the contribution to the total ion yield from single and multiple ionization to be distinguished and quantified. Such information yields relative partial ionization cross-sections (PICSs) and also allows relative precursor specific PICSs to be determined, which quantify the contribution from single, double and triple ionization to the relative yields of the fragment ions formed following electron-molecule collisions. Relative precursor specific PICSs therefore provide a more 'in-depth' chemical picture of each PICS. The relative precursor specific PICSs determined, following electron interaction with N20, provide clear evidence of energetic ion loss in previous cross-section determinations detailed in the literature. In addition, the 2D ion coincidence technique provides information on the energetics involved in the dissociation of any multiply charged ions formed. In the case of BCI3, further insight on the possible dissociation dynamics of BC132+ is reported. Following the investigations of N2O, BCI3 and SF6, the apparatus was commissioned to produce absolute partial ionization cross-sections and absolute precursor specific partial ionization cross-sections from 30-200 eV. Experimentally, the commissioning involved the addition of a Spinning Rotor Gauge (SRG) and a new gas inlet line to the source region. These investigations have extended the data determined for the electron ionization of N20 and have also enabled the absolute cross-section data for the electron ionization of C2H2 to be determined.
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3

Condren, D. S. "Wannier or relativistic ionization." Thesis, Queen's University Belfast, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.479245.

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4

Szluińska, Marta. "Positron induced ionization process." Thesis, University College London (University of London), 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.404930.

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5

Murtagh, Daniel James. "Positron impact ionization phenomena." Thesis, University College London (University of London), 2007. http://discovery.ucl.ac.uk/1446030/.

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In the present work, a beam of positrons, obtained from a radioactive source (MNa) in conjunction with a W moderator and guided by a magnetic field, has been used to investigate low energy positron-impact ionization phenomena from atomic and molecular targets. For He below threshold, the investigation discovered vacuum contaminants in creased with gas load and hence concluded that the high 7-ray/ion signal observed by Szluinska and Laricchia (2004a) in Ne could not be safely attributed to annihila tion. A detailed measurement of the total ionization cross-section for He has been performed from below threshold for Ps formation to high energy. Combined with previously measured data and previously measured direct ionization cross-sections (Moxom et al 1996, Ashley et al 1996), a new determination of the positronium formation cross-section has been achieved and compared to other available experi mental measurements and theoretical calculations. Measurements of the excited state (n > 1) positronium formation cross-section for He and Ar have been performed and compared to available theoretical calcu lations. This work has been motivated both for a direct comparison with theory and to test the hypothesis that structure observed in the total (all n) positron ium formation cross-sections for the heavier noble gases, is due to excited state positronium formation (Laricchia et al 2002). The present study is unable to verify fully this hypothesis due to the experimental methods insensitivity to positronium formation in to the 2S or n > 2 states. However, the present results are close to the most sophisticated theoretical calculation of positronium formation into the 2P state (Campbell et al 1998).
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6

TAVARES, ANDRÉ CARLOS. "MULTIPLE IONIZATION OF NOBLE GASES BY PROTONS: IONIZATION PROBABILITIES AND POST–COLISIONAL EFFECTS." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2011. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=18488@1.

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CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO
Nesta dissertação são apresentados cálculos detalhados de seções de choque de ionização múltipla de gases nobres por prótons de velocidades intermediárias. Foi realizado um estudo detalhado sobre a importância das probabilidades tanto de ionização direta de elétrons de cada subcamada como das probabilidades de emissão pós-colisional. Uma comparação com resultados teóricos e experimentais disponíveis na literatura também foi realizada. Com o intuito de investigar a influência dos valores adotados para as probabilidades de ionização em cada subcamada, foram realizadas versões que deixavam de levar em conta, gradativamente, a participação das diversas subcamadas do alvo. Foi analisada também a utilização de diferentes fontes de probabilidades de emissão pós-colisional. Observou-se que, para os estados de carga finais mais elevados, as seções de choque de ionização múltipla se tornam cada vez mais sensíveis tanto às probabilidades de ionização direta quanto às probabilidades de emissão pós-colisional.
In this dissertation, detailed calculations of multiple ionization cross sections of noble gases by intermediate-velocity protons are presented. A detailed study on the relative importance of the probabilities for both the direct ionization of electrons from a given sub-shell and the postcollisional emission has been performed. The cross sections obtained in this work have also been compared to the experimental data and theoretical results available in the literature. In order to investigate the influence of the adopted values for the probabilities of direct ionization of each target sub-shell, different versions of the general equations have been used, in which the participation of each sub-shell has been gradually neglected. The use of probabilities for postcollisional emission from different authors has also been analyzed. It was observed that, for higher final charge states, the multiple ionization cross sections become more and more sensitive to both the direct ionization and the post-collisions emission probabilities.
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7

Tung, Selena C. W. "Ionization of gases by slow monoenergetic electrons." Thesis, University of British Columbia, 1988. http://hdl.handle.net/2429/28351.

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Electron impact ionization is an important phenomenon touching many areas of science, and much research has been done over the years on various aspects of this process. Efforts to establish the precise variation of ionization cross section with energy were initiated in the early 1950's; however, severe disagreements between experimental data concerning fine structure observed in the electron impact ionization efficiency curves were reported from laboratory to laboratory. The work in this thesis has been largely devoted to establishing the credibility of the method of electron impact ionization by monoenergetic electron beam in the study of such fine structure. The design and construction of an apparatus to study the ionization of atoms and molecules by an electron beam of narrow energy width are described, and preliminary data on krypton and argon near the ionization threshold energies discussed. A sound basis has been laid for further development in this field.
Science, Faculty of
Chemistry, Department of
Graduate
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8

Almowalad, Najah K. "Elimination of Electrochemical Oxidation during Sample Ionization Using Liquid Sample Desorption Electrospray Ionization (DESI)." Ohio University / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1474911988216817.

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9

Trachy, Marc Lawrence. "Photoassociative ionization in cold rubidium." Diss., Manhattan, Kan. : Kansas State University, 2008. http://hdl.handle.net/2097/695.

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10

Curran, Edwin Paul. "Electron impact ionization of atoms." Thesis, Queen's University Belfast, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.328062.

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11

McSherry, D. M. "Ionization in ion-atom collisions." Thesis, Queen's University Belfast, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.368567.

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12

Ashley, Paul Newton. "Investigation of positron impact ionization." Thesis, University College London (University of London), 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.362381.

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13

Lee, Hong-Wei. "Solid-State Impact-Ionization Multiplier." BYU ScholarsArchive, 2006. https://scholarsarchive.byu.edu/etd/1080.

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This dissertation presents an innovative solid-state current amplifier based on impact-ionization. Unlike avalanche photodetectors which use the same amplification principle, this device can be integrated with any external current source. A discrete amplifier was built on a silicon surface using standard CMOS fabrication processes including lithography, oxidation, ion implantation, diffusion, chemical wet etching, metal deposition, annealing, and rapid thermal processing. Testing was performed by connecting the device to a silicon photodiode, indium-gallium-arsenide photodiodes, and a function generator to demonstrate its compatibility with arbitrary current sources. Current gains above 100 along with pre-amplified leakage currents of less than 10 nA were measured. This amplifier can also be cascaded to achieve very high gains similar to the photomultiplier tube but with much smaller size and no vacuum environment required. Testing was done by amplifying the output signal from an external silicon photodiode. Current gains over 600 were measured when two amplifying devices were cascaded. Additionally, the gain saturation phenomenon of the amplifier due to the space-charge effect is investigated. The measured gain saturation is observed to match very well with the theoretical based predictions. We also present a design rule for obtaining high current gain from the cascaded structure without experiencing gain saturation. Initial bandwidth of the SIM when connected to a silicon photodiode was measured to be about 300 kHz. As we replace the photodiode by a function generator, the bandwidth improved to 450 kHz which is the frequency limit of the system. These results were made on the first generation of SIM devices. We discovered that the space-charge resistance Rsc plays a significant role in determining frequency response. In future generations of the device, we can begin with optimizing the device geometry to reduce this resistance. Also, we can reduce the size of the metal pad and increase the oxide layer thickness to further minimize the device capacitance for faster response. Because of the low-noise gain mechanism employed, this device is of potential interest to a variety of fields requiring high-sensitivity optical or electronic detection.
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14

Adeoti, Bosun J. "Field ionization from carbon nanofibers." Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/45826.

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Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2008.
Includes bibliographical references (p. 109-111).
The Micro Gas Analyzer project aims to develop power-efficient, high resolution, high sensitivity, portable and real-time gas sensors. We developed a field ionizer array based on gated CNTs. Arrays of CNTs are used because of their small tip radii and high aspect ratio which yields high electric fields at low voltages. One possible configuration for the device is to bias the CNTs at the highest potential, and the collector or anode at the lowest potential. In this configuration, the electrons in the outer shell of the molecules tunnel out due to the high local electric fields which serve to lower the unperturbed potential barrier seen by the electrons. The tunneling effect is a purely quantum-mechanical process whose probability of occurrence is strongly dependent on the applied electric fields.We optimize the theoretical current obtainable from the Field Ionization Array (FIA) by varying structural parameters in our device. The most relevant parameters include the radius of curvature, height, base radius and base angle of the grown tip; height and thickness of the tip; and the gate aperture. Varying the gate (or oxide) height without updating the height of the CNT yields the derivable result that the electric field is maximized when the tip is at about the same height as the gate. We demonstrate field ionization of Argon from multi-walled CNTs and provide a numerical framework for analyzing the generated ion currents in cases where the surface electric fields are low.
by Bosun J. Adeoti.
M.Eng.
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15

Yu, Youliang. "Computationally exploring ultrafast molecular ionization." Diss., Kansas State University, 2017. http://hdl.handle.net/2097/38548.

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Doctor of Philosophy
Department of Physics
Brett D. Esry
Strong-field ionization plays a central role in molecules interacting with an intense laser field since it is an essential step in high-order harmonic generation thus in attosecond pulse generation and serving as a probe for molecular dynamics through either the sensitivity of ionization to the internuclear separation or the laser-induced electron scattering. Strong-field molecular ionization has been studied both theoretically and experimentally, dominantly through the Born-Oppenheimer approximation and at equilibrium or small reaction distances. We have extended the theoretical studies of molecular ionization to a much broader extent. Specifically, due to the difficulty of treating ionization in Born-Oppenheimer representation especially for molecular dynamics involving strongly-correlated electron-nuclear motion, we have investigated an alternative time-independent--adiabatic hyperspherical--picture for a one-dimensional model of the hydrogen molecule. In the adiabatic hyperspherical representation, all the reaction channels--including ionization--for the hydrogen molecule have been identified in a single set of potential curves, showing the advantage of studying molecular dynamics involving multiple breakup channels coupled with each other. We have thus proposed a good candidate to study strongly-correlated molecular dynamics, such as autoionization and dissociative recombination. Moving to a time-dependent picture by numerically solving the time-dependent Schrödinger equation (TDSE), we have explored two extreme classes of strong-field ionization of hydrogen molecule ion: at large internuclear distances (R>30 a.u.) and for long-wavelength laser fields. Remarkably, we have found strong-field two-center effects in molecular ionization beyond the long-standing one-photon two-center interference as a manifestation of the double-slit interference. In particular, the total ionization probability at large internuclear distances shows strongly symmetry-dependent two-center dynamics in homonuclear diatomic molecules and two-center induced carrier-envelope phase effect in heteronuclear diatomic molecules. Such two-center effects are expected to generalize to other diatomic systems and could potentially be used to explain phenomena in multi-center strong-field physics. Moreover, we have theoretically confirmed, for the first time, the existence of low energy structure in molecular ionization in long-wavelength laser fields by solving the three-dimensional TDSE. Finally, we have performed a pump-probe study of the hydrogen molecular ion where a pump pulse first dissociates the molecule followed by a probe pulse which ionizes the dissociating wave packet, and surprisingly found a pronounced broad ionization peak at large R or large pump-probe delay (~150 fs). Numerically, we have developed and implemented new theoretical frameworks to more accurately and efficiently calculate quantum mechanical processes for small molecules--hydrogen molecule and its ion--which could readily be adapted to heavier diatomic systems.
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16

Vogel, David Arthur. "Electron impact ionization of highly charged lithiumlike ions." Diss., Georgia Institute of Technology, 1992. http://hdl.handle.net/1853/30886.

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17

Walker, Mark Allen. "Single-Electron Structure and Dynamics in the Strong-Field Photoionization of Noble Gas Atoms and Diatomic Molecules." The Ohio State University, 2002. http://rave.ohiolink.edu/etdc/view?acc_num=osu1039125206.

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18

Hoang, Khoa Duc Nguyen. "Development and Application of Novel Sample Introduction for Matrix Assisted Ionization and Solvent Assisted Ionization." Thesis, University of the Sciences in Philadelphia, 2019. http://pqdtopen.proquest.com/#viewpdf?dispub=13862022.

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Mass spectrometry (MS) is an efficient analytical tool due to a number of advantages for providing high sensitivity, high-throughput analysis and less sample consumption. Since 1897, MS has continued to evolve and significant developments have occurred in the area of ionization techniques. Since 2010, inlet ionization techniques have shown the potential to compete in the areas of sensitivity and sample conservation with electrospray ionization (ESI) and matrix assisted laser desorption/ionization (MALDI). Matrix assisted inlet ionization (MAI) produces multiply charged ions within a mass spectrometer inlet without the need of high voltage, a laser or nebulizing gas. For MAI, sample preparation can be critical affecting the sensitivity, reproducibility and carry over. This dissertation presents new sample preparation techniques which have shown substantial improvement in sensitivity and reproducibility. The limit of detection can be achieved to less than 50 amol with the new sample preparation technique. Furthermore, this new sample introduction process enhance matrix assisted ionization (MAI) and solvent assisted ionization (SAI)’s ability to couple with Thin-layer chromatography.

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19

Schug, Kevin Albert. "Pseudo-Molecular Ion Formation by Aromatic Acids in Negative Ionization Mode Electrospray Ionization Mass Spectrometry." Diss., Virginia Tech, 2002. http://hdl.handle.net/10919/29886.

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Pseudo-molecular ion formation is an artifact common to most analyses performed by electrospray ionization mass spectrometry. These species are non-covalent complexes formed between an analyte of interest and any other components (such as mobile phase, additives, and impurities) present in the ionized sample band. Published literature addresses pseudo-molecular ion formation in routine analyses as well as in complicated molecular recognition processes. The majority of these works are directed towards the formation of complexes in the positive ionization mode. Consequently, investigation of pseudo-molecular ion formation in the negative ionization mode is a logical extension of work in this area. Experiments presented here detail the work performed on elucidation of factors controlling ionization efficiency of aromatic acid pseudo-molecular ions by electrospray ionization in the negative ionization mode. Sets of tested acidic analytes, including ibuprofen derivatives and benzoic acid derivatives, were analyzed in the presence of various solution systems by flow injection analysis to determine the effect of pH, concentration, injection volume, and instrumental parameters on dominant ion forms observed in the mass spectra. These ion forms correspond to a deprotonated molecular ion ([M-H]-), a hydrogen-bound dimer ion ([2M-H]-), and a sodium-bridged dimer ion ([2M-2H+Na]-). Report of the latter ion form is unique to this work. Response of these ion forms were found to vary greatly with changing solution parameters, particularly in the presence of common LC-MS modifiers, such as triethylamine, acetic acid, formic acid, and ammonium formate. Results point to the formation of the sodium-bridged dimer ion during gas-phase processes following the release of ions from disintegrated droplets. Ab initio theoretical calculations and correlations with calculated solution phenomena (such as pKa and log P) were used to elucidate structural arrangements and dominant factors controlling pseudo-molecular ion formation by aromatic acids in the negative ionization mode.
Ph. D.
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20

Naubereit, Pascal [Verfasser]. "Resonance Ionization Spectroscopy of Protactinium : Studies on Intrinsic Quantum Chaos and the Ionization Potential / Pascal Naubereit." Mainz : Universitätsbibliothek der Johannes Gutenberg-Universität Mainz, 2020. http://d-nb.info/1224896270/34.

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21

Lensegrav, Craig T. "Advanced quantification of plutonium ionization potential to support nuclear forensic evaluations by resonance ionization mass spectrometry." Thesis, Monterey, California: Naval Postgraduate School, 2015. http://hdl.handle.net/10945/45889.

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Ongoing work seeks to apply the technology of resonance ionization mass spectrometry (RIMS) to problems related to nuclear forensics and, in particular, to the analysis and quantification of the debris from nuclear detonations. As part of this effort, modeling and simulation methods are being applied to analyze and predict the potential for ionization by laser excitation of isotopes of both uranium and plutonium. Early work focused on the ionization potential of isotopes of uranium, and the present effort has expanded and extended the previous work by identifying and integrating new data for plutonium isotopes. In addition to extending the effort to this important new element, the work described in this thesis implemented more accurate descriptions of the spatial distribution of the laser beams to improve the accuracy of model predictions compared with experimental results as well as an ability to readily incorporate new experimental data as they become available. The model is used to estimate ionization cross sections and to compare the relative excitation potential for two isotopes as a function of wavelength, irradiance, and bandwidth.
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22

Kübel, Matthias. "Single-cycle non-sequential double ionization." Diss., Ludwig-Maximilians-Universität München, 2014. http://nbn-resolving.de/urn:nbn:de:bvb:19-180183.

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23

Marchalant, Pascale J. "(e, 2e) excitation-ionization of helium." Thesis, Queen's University Belfast, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.337019.

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24

Rogers, Kevin Shaun. "Laser desorption/laser ionization mass spectroscopy." Thesis, University of Salford, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.357037.

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25

Hatherly, P. A. "The multiphoton multiple ionization of molecules." Thesis, University of Reading, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.234654.

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26

Rocca, F. J. "Ionization damage mechanisms in electron microscopy." Thesis, University of Cambridge, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.372301.

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27

Corsten, Maria J. (Maria Joanne) Carleton University Dissertation Physics. "Ionization chamber response for brachytherapy sources." Ottawa, 1995.

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28

Jang, Daniel M. Eng Massachusetts Institute of Technology. "Carbon nanotube-based field ionization vacuum." Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/77022.

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Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2012.
Cataloged from PDF version of thesis.
Includes bibliographical references (p. 101-105).
We report the development of a novel micropump architecture that uses arrays of isolated vertical carbon nanotubes (CNT) to field ionize gas particles. The ionized gas molecules are accelerated to and implanted into a negatively biased getter removing the gas molecules from the volume being pumped. CNTs are ideal for field ionization because of their nano-sized diameter, high aspect ratio and of their robust chemical and mechanical structure. The ionizing CNTs are biased at a much higher electrical potential than the gate material surrounding it. Because of the high aspect ratio of CNTs, the area near the tip of the ionizing CNT exhibits very high electric field strength. Gas molecules that are in close proximity to the CNT tips are ionized when electrons tunnel from the gas molecules to the CNT tips. A negatively biased getter positioned nearby attracts the ionized gas molecules, which are implanted in the getter material. With the gas molecules removed from the enclosed space, reduction of the pressure is achieved. Key challenges in this Field Ionization Pump (FIP) project were the fabrication of high yield working pumps and a high enough ionization current at low voltages. The FIP is designed to evacuate volumes from low vacuum (30 Torr) to mid-vacuum (30 Torr). We designed the device using electrostatic simulations. Several designs for the FIP ionizers were developed, and we created a device capable of producing field ionization current of 4 nA using an array of 96 field ionizers with 700 V bias voltage at 5 - 10-⁵ Torr. We also show that ion implantation of the ionized atmospheric gas occurs in a silicon getter biased at 1000 V, which is confirmed via X-ray photoelectron spectroscopy (XPS).
by Daniel Jang.
M.Eng.
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29

Lomsadze, Bachana. "Ionization in direct frequency comb spectroscopy." Diss., Kansas State University, 2012. http://hdl.handle.net/2097/15101.

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Doctor of Philosophy
Department of Physics
Brett D. DePaola
Direct frequency comb spectroscopy (DFCS) is currently the highest resolution, absolute frequency spectroscopic technique known. In general, one does DFCS by scanning the repetition rate, f[subscript]r[subscript]e[subscript]p, of a comb laser and measuring fluorescence from the excited states of the specie under study. The technique has already been successfully characterized by a theoretical model that starts with the optical Bloch equations and, with a few simplifying assumptions converts them into linear coupled iterative equations. In the present work we build on that successful model to predict the characteristics of the ion yield from photoionization by the comb laser, as a function of f[subscript]r[subscript]e[subscript]p. We show that the ion spectrum yields the same atomic structure as the fluorescence spectra, but with greater efficiency. Here, we also set up an experiment and test this theory by measuring the ion signal from direct frequency comb spectroscopy. Furthermore, instead of actively controlling the frequency comb parameters, we allow them to drift, passively measuring them and the ion signal simultaneously. The experiments were found to be in agreement with theory, and the passive comb approach was found to be functional, though not as convenient as the conventional active comb.
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Ben, Taher Azza. "Strong Optical Field Ionization of Solids." Thesis, Université d'Ottawa / University of Ottawa, 2018. http://hdl.handle.net/10393/37151.

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Population transfer from the valence to conduction band in the presence of an intense laser field is explored theoretically in semiconductors and dielectrics. Experiments on intense laser driven dielectrics have revealed population transfer to the conduction band that differs from that seen in semiconductors. Our research explores two aspects of ionization in solids. (i) Current ionization theories neglect coupling between valence and conduction band and therewith the dynamic Stark shift. Our single-particle analysis identifies this as a potential reason for the different ionization behaviour. The dynamic Stark shift increases the bandgap with increasing laser intensities thus suppressing ionization to an extent where virtual population oscillation become dominant. The dynamic Stark shift plays a role dominantly in dielectrics which due to the large bandgap can be exposed to significantly higher laser intensities. (ii) In the presence of laser dressed virtual population of the conduction band, elastic collisions potentially transmute virtual into real population resulting in ionization. This process is explored in context of relaxation time approximation.
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31

Volný, Michael. "Reactive and soft landing of polyatomic gas-phase ions on plasma-treated metal surfaces /." Thesis, Connect to this title online; UW restricted, 2006. http://hdl.handle.net/1773/8650.

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32

Isselhardt, Brett Hallen. "Quantifying Uranium Isotope Ratios Using Resonance Ionization Mass Spectrometry: The Influence of Laser Parameters on Relative Ionization Probability." UNIVERSITY OF CALIFORNIA, BERKELEY, 2013. http://pqdtopen.proquest.com/#viewpdf?dispub=3498831.

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33

May, Christian. "Impact ionization rate calculations for device simulation." Zürich : ETH, Eidgenössische Technische Hochschule Zürich, Integrated Systems Laboratory, 2005. http://e-collection.ethbib.ethz.ch/show?type=dipl&nr=376.

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34

Grange, Andrew H. "Medium resolution atmospheric pressure ionization mass spectrometry /." Full text open access at:, 1988. http://content.ohsu.edu/u?/etd,158.

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35

Wang, Jing Cheng. "Photoionization and electron-impact ionization of Ar5+." abstract and full text PDF (free order & download UNR users only), 2006. http://0-gateway.proquest.com.innopac.library.unr.edu/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3221392.

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36

Jatcko, Mark Edward. "Ionization-structure relationships in metal-phosphine interactions." Diss., The University of Arizona, 1989. http://hdl.handle.net/10150/184942.

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The techniques of valence photoelectron spectroscopy (PES), X-ray diffraction, molecular orbital calculations, and multi-nuclear NMR are combined in a comparison of metal-phosphine bonding in a series of phosphine substituted molybdenum and tungsten metal carbonyl complexes, M(CO)(6-n)(P)(n) [n = 1,2,3,4,6]. The phosphine, P, represents either the mono-dentate phosphine, PMe₃, or one phosphine unit in the diphosphines, Me₂P(CH₂)ₓPMe₂, [x = 1, bis(dimethylphosphino)methane (DMPM); x = 2, 1,2-bis(dimethylphosphino)ethane (DMPE)]. Comparison of PMe₃ and the diphosphines in mono-dentate coordination (i.e. η¹-Mo(CO)₅DMPE) indicates the σ-donor strength is essentially identical for the three phosphines studied. Comparison of PMe₃ and the diphosphines in cis-chelating geometries reveals essentially identical charge at the coordinated phosphorus atoms and nearly identical charge at the metal center for cis-M(CO)₄(PMe₃)₂ and cis-M(CO)₄DMPE despite different local P-M-P bond angles. The X-ray crystal structures reveal a "twist" of the phosphine ligand when in sterically strained coordination geometries. The phosphine twist results in a "bent" metal-phosphine bond and is evaluated based on both electronic and steric considerations. The phosphine twist principle is used in studies on the nature of phosphine ligand electronic effects in the M(CO)(6-n)(P)(n) series at high substitution numbers, n. The PES data of the DMPE complexes for n = 4, cis-Mo(CO)₂(DMPE)₂, and n = 6, Mo(DMPE)₃, show symmetric metal electronic structure, but also a deviation from the previously observed additive behavior of phosphine electronic effects. The PES data for cis-Mo(CO)₂(PMe₃)₄ reveal a symmetric metal electronic structure due to sterically induced ligand-ligand interactions in this metal carbonyl complex. Multi-nuclear NMR data (³¹P and ⁹⁵Mo) are presented and the results discussed in light of the important ligand-ligand interactions observed in the PES studies. In addition, comparison of the NMR results for the mono-dentate and chelating phosphine complexes and the PES metal electronic structures provides a possible contribution to the ring chelate effect that is observed in the ³¹P and ⁹⁵Mo chemical shifts. The ring chelate effect refers to the unexplained relative differences between the ³¹P and ⁹⁵Mo chemical shifts of the cis-(PR₃)₂ complexes and the chelating diphosphine analogues.
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37

Rivara, Nick. "IC Engine Control by Ionization Current Sensing." Thesis, University of Liverpool, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.510971.

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38

Cooke, D. A. "Positron impact ionization of atoms and molecules." Thesis, University College London (University of London), 2010. http://discovery.ucl.ac.uk/624495/.

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In the present work, a beam of monoenergetic positrons has been used to investigate the ionization of atoms and small molecules at energies below 1 keV. The beam was produced from the radioactive decay of a ²²Na source combined with W-mesh moderators and a magnetic guidance system. The first measurements of the cross-sections for excited-state positronium formation from Xe and simultaneous ionization–excitation cross-sections for positron impact on CO₂ and N₂ have been performed. Near-complete characterization of the detection system coupled with the ability to measure several processes simultaneously allowed the collection of data sets which were internally self-consistent. By normalizing the total ionization cross-section, an absolute scale could be applied to all measurements. A number of methods for achieving this were employed, as a check on external consistency. The cross-section for excited-state positronium formation from Xe completed a study (Murtagh et al., 2009) in Ps formation from the noble gases. The measurement has defined a trend of increasing maximal fraction of Ps formed into the 2P state with increasing atomic number. The measurements of ionization–excitation for molecular targets (Cooke et al., 2010a) reveal that this process is enhanced over the equivalent interaction involving electrons. This enhancement arises mainly (or exclusively, in the case of CO₂) from the effect of positronium formation, over and above the corresponding enhancement in the total ionization cross-section. Based on this observation, and the comparative lack of excited-state Ps detected in these targets, a mechanism for the enhancement involving an accidental resonance between a neutral excited molecular state and an ionic state with Ps formation has been proposed. The cross-sections for ionization–excitation were measured contemporaneously with a full suite of ionization cross-sections.
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39

McCartney, Mark. "Ionization processes in multielectron ion-atom collisions." Thesis, Queen's University Belfast, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.359106.

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40

Purvis, John. "R-matrix-Floquet Theory of multiphoton ionization." Thesis, Queen's University Belfast, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.239216.

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41

Strahand, M. A. "Time resolved multiphoton ionization of aromatic molecules." Thesis, University of Manchester, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.377723.

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42

Randerson, Patrick J. "Fundamental dynamics in high intensity laser ionization." Connect to this title online, 2005. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1110219813.

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Thesis (Ph. D.)--Ohio State University, 2005.
Title from first page of PDF file. Document formatted into pages; contains xv, 145 p.; also includes graphics (some col.) Includes bibliographical references (p. 138-145). Available online via OhioLINK's ETD Center
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43

Zu, Chengli. "Enantiomer analysis using electrospray ionization mass spectrometry." Diss., Mississippi State : Mississippi State University, 2007. http://library.msstate.edu/etd/show.asp?etd=etd-04092007-103342.

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44

Pourcelot, Grégoire. "Characterization of boron coating in ionization chambers." Thesis, KTH, Fysik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-250319.

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45

Sheppard, Eric J. (Eric James). "Ionization nonequilibrium and ignition in plasma accelerators." Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/47344.

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46

Kay, Ewan Samuel. "Numerical models of Hall thruster ionization oscillations." Thesis, Massachusetts Institute of Technology, 2016. http://hdl.handle.net/1721.1/105563.

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Thesis: S.M., Massachusetts Institute of Technology, Department of Aeronautics and Astronautics, 2016.
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 141-143).
In this thesis, low frequency ionization oscillations in Hall thrusters resembling the breathing mode are studied through computational simulation. The relationship between wall erosion and discharge current oscillations is analyzed using particle-in-cell simulation, and a series of parametric simulations is used to determine the effects of macro-particle size, floating body potential, electron injection region, ion time step size, grid refinement, heavy particle mass reduction, and an artificial permittivity factor. These studies help to determine the parameters that will produce accurate simulations in the future, and identify the parts of the model that need improvement. One-dimensional steady and unsteady Hall thruster models, as well as a generalized sheath model are then developed, and the effects of the parameters that determine stability on the thruster's operating conditions are determined.
by Ewan Samuel Kay.
S.M.
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47

Chatzipetros, Argyrios. "A simple model of above threshold ionization." Thesis, Virginia Tech, 1990. http://hdl.handle.net/10919/42087.

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48

Soriano, Joey Kim Tumbali. "Novel plasma-based ambient desorption/ionization source." Thesis, https://doors.doshisha.ac.jp/opac/opac_link/bibid/BB13133185/?lang=0, 2020. https://doors.doshisha.ac.jp/opac/opac_link/bibid/BB13133185/?lang=0.

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周囲プラズマベースの周囲脱離/イオン化ソースにより、従来の大気圧イオン化では不可能な周囲条件下でのサンプルの直接分析が可能になります。これにより、面倒な準備と、多くの有害で複雑なサンプルの分析用質量分析計への導入が解消されます。既存のプラズマベースのアンビエント脱離/イオン化ソースは、通常、2つの電極間にキロヘルツから数メガヘルツの範囲の周波数で直流（DC）または交流（AC）電圧を印加することによって形成されます。この研究では、新しいプラズマベースの周囲脱離/イオン化は、13.56 MHz RFソースから供給される非常に低い電力密度で動作する誘導結合によって生成されたワイヤ安定化大気圧プラズマで構成されています。ワイヤ安定化大気圧プラズマの点火特性、安定性およびプラズマ特性を研究した。
Ambient plasma-based ambient desorption/ionization source enables direct analysis of samples under ambient conditions that traditional atmospheric pressure ionization is incapable. It overcomes the tedious preprocessing and often detrimental and complicated sample introduction to the mass spectrometer for analysis. Existing plasma-based ambient desorption/ionization sources feature an electrical discharge typically formed between two electrodes by applying either a direct-current (DC) voltage or an alternating-current (AC) voltage with frequencies ranging from kilohertz to several megahertz. In this study, a novel plasma-based ambient desorption/ionization consists of a wire stabilized atmospheric pressure plasma produced by inductive coupling operated at very low power density supplied by a 13.56 MHz RF source. The ignition characteristics, stability and plasma properties of the wire stabilized atmospheric pressure plasma were studied.
博士(工学)
Doctor of Philosophy in Engineering
同志社大学
Doshisha University
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49

Welton, Robert Frederick. "The formation of metastable and multiply charge ions." Diss., Georgia Institute of Technology, 1994. http://hdl.handle.net/1853/30371.

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50

Smyth, Edward Stuart. "Theory and computation of atoms in intense laser fields." Thesis, Queen's University Belfast, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.287427.

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