Rozprawy doktorskie: „Electron impact”

1

Sze, Kong Hung. "Electronic excitation of polyatomic molecules by fast electron impact". Thesis, University of British Columbia, 1988. http://hdl.handle.net/2429/29302.

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High resolution electron energy loss spectroscopy has been used to examine the inner-shell and valence-shell electronic excitation of a number of polyatomic molecules, including SF₆, SeF₆, TeF₆, ClF₃, C₂H₃F, C₂H₃Cl, C₂H₃Br, C₂H₃I, Ni(CO)₄, (CH₃)₂SO and SO₂. The inner-shell and valence-shell electron energy loss spectra (ISEELS and VSEELS) were measured under low momentum transfer conditions with impact energy in the range of 1-3.7 keV and 0° scattering angle. Under these conditions the spectra are dominated by electric dipole-allowed transitions. The ISEELS spectra include all accessible core excitations of these molecules below 1000 eV equivalent photon energy. A number of specific investigations have been performed in order to extend present understanding of the physical nature of electronic excitation phenomena, in particular those involving inner-shell electrons. In addition the present work illustrates new applications of ISEELS to the study of chemical phenomena. In the investigation of (Coulombic) potential barrier effects in the "cage" molecules SF₆, SeF₆, TeF₆ and ClF₃, f-type continuum shape resonances are observed for the first time in the spectra of TeF₆ and they show very different spectral behavior from the d-type continuum shape resonances observed in the spectra of SF₆ and SeF₆. Consideration of both the ISEELS and VSEELS spectra indicates that there is a weakening of the potential barrier in going through the series from SF₆ to SeF₆ to TeF₆. The Coulombic potential barrier model provides an extremely satisfactory understanding of (a) the co-existence of intense continuum shape resonances and intense Rydberg transitions plus direct ionization continuum; and (b) the number and symmetry of continuum shape resonances observed in the ISEELS spectra of ClF₃. The physical significance of Coulombic potential barrier effects is further convincingly demonstrated by a comparison of the "central atom" inner-shell spectra of SF₆, ClF₃ and HCl. In contrast to earlier work, the present comparative study of the He(I) and He(II) photoelectron spectra and the VSEELS excitation spectra of the monohaloethylenes (i.e. C₂H₃X; X = F, Cl, Br and I) suggests that the HOMO orbital in C₂H₃I is predominantly of iodine 5p[sub ⊥](out-of-plane) character rather than of π character whereas the reverse situation applies to the HOMO orbitals of C₂H₃F, C₂H₃Cl and C₂H₃Br. Based on a term value correlation analysis, substitutional effects are found to be most prominent in the σ* -type orbitals, while the π* and Rydberg orbitals are less influenced. Linear correlations between the C-X bond strength and the term values for both inner-shell and valence-shell transitions to the σ* (CX) orbital are also observed. The ISEELS and VSEELS spectra of Ni(CO)₄ are compared with the corresponding spectra in free CO. The C and O Is spectra of these two molecules show some notable similarities despite the very different manifold of final states available. In particular the inner-shell spectra of both molecules exhibit intense ls → π* and ls → σ* transitions. High resolution ISEELS has been used to obtain vibrational resolved C Is spectra of Ni(CO)₄ and free CO. The implications and possibilities of studying dπ →pπ back-bonding in transition metal carbonyl complexes by high resolution ISEELS spectroscopy are discussed. The inner-shell (S 2s, 2p, C Is) excitations of (CH₃)₂SO (DMSO) measured by ISEELS are compared with synchrotron radiation studies of the S Is photoabsorption spectrum. The pre-edge regions of these spectra are interpreted as excitations to common manifolds of virtual valence and Rydberg orbitals. A linear correlation between the S-C bond lengths and the term values of S 2p[sub 3/2] → σ* (S-C) transitions is demonstrated for DMSO and a number of other sulfur compounds. The S 2p, 2s and O Is ISEELS spectra of SO₂ as well as the S ls photoabsorption spectrum are compared with and assigned according to the results of multichannel quantum defect theory calculations. The calculated energies and oscillator strengths of spectral features in these spectral regions are generally in good quantitative agreement with the measurements.
Science, Faculty of
Chemistry, Department of
Graduate

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2

Bartlett, Philip Lindsay. "Complete numerical solution of electron-hydrogen collisions". Thesis, Bartlett, Philip Lindsay (2005) Complete numerical solution of electron-hydrogen collisions. PhD thesis, Murdoch University, 2005. https://researchrepository.murdoch.edu.au/id/eprint/225/.

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This thesis presents an extensive computational study of electron-impact scattering and ionisation of atomic hydrogen and hydrogenic ions, which are fundamental to many diverse disciplines, from astrophysics and nuclear fusion to atmospheric physics. The non-relativistic Schrodinger equation describes these collisions, though finding solutions for even hydrogen, the simplest electron-atom collision, has proven to be a monumental task. Recently, Rescigno et al [Science 286, 2474 (1999)] solved this equation in coordinate space using exterior complex scaling (ECS), and presented the first electron-hydrogen differential cross sections for ionisation that matched with experiment without requiring uncontrolled approximation. This method has significant potential for extension to larger collision systems, but its large computational demand has limited its energy range and target configurations, and its application to discrete final-state collisions has been largely unexplored. Using radically different numerical algorithms, this thesis develops methods that improve the computational efficiency of ECS by two orders of magnitude. It extends the method to calculate discrete final-state scattering cross sections and enhances the target description to include hydrogenic ions and excited initial states. In combination, these developments allow accurate solutions over a broad range of energies and targets, for both scattering and ionisation, including the important near-threshold energy region where accurate calculations have been unavailable. The refined ECS method implemented in this work now offers complete numerical solutions of electron-hydrogen collisions, and its computational efficiency will facilitate its future application to more complex targets. The thesis culminates with the first ab initio quantum mechanical confirmation of ionisation threshold laws for electron-hydrogen collisions [Bartlett and Stelbovics, 2004, Phys. Rev. Lett. 93, 233201], which have resisted confirmation through the complete solution of the Schrodinger equation for more than half a century.

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3

Bartlett, Philip Lindsay. "Complete numerical solution of electron-hydrogen collisions". Bartlett, Philip Lindsay (2005) Complete numerical solution of electron-hydrogen collisions. PhD thesis, Murdoch University, 2005. http://researchrepository.murdoch.edu.au/225/.

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This thesis presents an extensive computational study of electron-impact scattering and ionisation of atomic hydrogen and hydrogenic ions, which are fundamental to many diverse disciplines, from astrophysics and nuclear fusion to atmospheric physics. The non-relativistic Schrodinger equation describes these collisions, though finding solutions for even hydrogen, the simplest electron-atom collision, has proven to be a monumental task. Recently, Rescigno et al [Science 286, 2474 (1999)] solved this equation in coordinate space using exterior complex scaling (ECS), and presented the first electron-hydrogen differential cross sections for ionisation that matched with experiment without requiring uncontrolled approximation. This method has significant potential for extension to larger collision systems, but its large computational demand has limited its energy range and target configurations, and its application to discrete final-state collisions has been largely unexplored. Using radically different numerical algorithms, this thesis develops methods that improve the computational efficiency of ECS by two orders of magnitude. It extends the method to calculate discrete final-state scattering cross sections and enhances the target description to include hydrogenic ions and excited initial states. In combination, these developments allow accurate solutions over a broad range of energies and targets, for both scattering and ionisation, including the important near-threshold energy region where accurate calculations have been unavailable. The refined ECS method implemented in this work now offers complete numerical solutions of electron-hydrogen collisions, and its computational efficiency will facilitate its future application to more complex targets. The thesis culminates with the first ab initio quantum mechanical confirmation of ionisation threshold laws for electron-hydrogen collisions [Bartlett and Stelbovics, 2004, Phys. Rev. Lett. 93, 233201], which have resisted confirmation through the complete solution of the Schrodinger equation for more than half a century.

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4

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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5

Leighton, Gary James. "Electron impact excitation of neon". Thesis, University of Newcastle Upon Tyne, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.435562.

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6

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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7

Wasson, Ian Randal. "Electron impact excitation of Cr II". Thesis, Queen's University Belfast, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.580115.

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There is overwhelming demand for accurate atomic data for Chromium 11, critical in the analysis of a broad range of astrophysical bodies. This thesis is the largest calculation undertaken for the electron-impact excitation of Cr 11. The target model, determined using CIV3, consists of the 3 configurations 3d5, 3d~s and 3d44p corresponding to a 280 jj-Ievel, 1932 coupled channel problem. A further 7 Configuration Interaction terms are included along with a 4d pseudo orbital. The scattering calculation internal region was completed using RMATRX 11 plus the module FINE to account for relativistic effects and then PSTGF is used for the external region. Collision strengths and Maxwellian averaged effective collision strengths are calculated and comparisons are made with the work of Bautista et al. (2009). A mixed bag of results are observed with good agreement across many transitions but significant differences for others. The Cr 11 model is also used with RMATRX I in a full Breit-Pauli Hamiltonian treatment. Code limitations force this calculation to be completed for a limited number of In partial ) waves. Comparisons are made for a number of transitions and excellent agreement is found between the results from these two very different codes and methodologies. This strong correlation provides a stringent test between an LS-coupling with transformation approach to include relativistic effects and a full Breit-Pauli treatment. This work was undertaken in collaboration with Auburn University, Alabama, thanks to the Caldwell scholarship. Work has also been started on the development of CIV3 to make use of coefficients of fractional grandparentage. Adopting the associated theory to extract two electrons from the same subshell dramatically decreases the time taken in large atomic structure calculations. Finally, I present utility codes that have significantly increased efficiency and have proven useful in the Cr 11 calculation and analysis of the results.

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8

Kelly, Stephen D. "Molecular fluorescence induced by electron impact". Thesis, Heriot-Watt University, 1985. http://hdl.handle.net/10399/1621.

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9

King, Sean J. "Electron impact excitation of krypton atoms". Thesis, Queen's University Belfast, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.317100.

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10

Yalim, Hueseyin Ali. "Electron impact excitation of atomic hydrogen". Thesis, University of Newcastle Upon Tyne, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.388151.

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11

Lu, Miao. "Photoionization and electron-impact ionization of multiply charged krypton ions". 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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12

Ayling, Stephen Gerard. "Cross-sections and electron distributions relating to hot electron impact excitation efficiencies". Thesis, University of St Andrews, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.328092.

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13

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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14

Kaiser, Christian Dieter. "Electron impact ionisation of atoms and molecules". Thesis, University of Manchester, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.515113.

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(e,2e) spectroscopy is a versatile tool to investigate the collision dynamics taking place in electron impact ionisation of atoms and molecules as it employs a kinematically complete view of the scattering process. (e,2e) measurements on He and H2 have been carried out from the coplanar to the perpendicular geometry at various impact energies, and these results are compared and discussed. Results for the atomic targets He, Ar and Xe and the molecular targets H2, N2 and CO2 are also presented from measurements in the perpendicular geometry and these are compared. The Ib1 molecular orbital of H20 has been studied at low to intermediate energies in a coplanar symmetric and asymmetric geometry. Where available the experimental data have been compared to theoretical calculations of other research groups located in the USA. A new coincidence spectrometer has been designed, assembled and commissioned which incorporates a pulsed, supersonic beam expansion as well as a continuous, effusive beam expansion. Measurements using supersonically expanded He and H2 demonstrated the feasibility of the new coincidence spectrometer for (e,2e) studies. The supersonic gas expansion provides molecular targets in their ground ro-vibrational states. This spectrometer allows the first steps towards the development of molecular alignment within the target beam. The alignment of diatomic molecules in the experiments would open up a new range of (e,2e) measurements with far-reaching implications for the investigation of collision dynamics from molecules.

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15

Ancarani, Lorenzo Ugo. "Electron impact excitation of atoms and positive ions". Thesis, University of Cambridge, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.360626.

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16

Trevisan, Cynthia Sandra. "Near threshold electron impact dissociation of molecular hydrogen". Thesis, University College London (University of London), 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.397950.

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17

Bukhari, Muhammad Abdul-Hakim. "Electron impact excitation of polarised sodium and potassium". Thesis, University of Stirling, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.294067.

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18

Caló, A. (Antonio). "Electron spectroscopy of atoms and molecules using synchrotron radiation, UV radiation and electron impact". Doctoral thesis, University of Oulu, 2007. http://urn.fi/urn:isbn:9789514286650.

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Abstract The present thesis investigates the electronic structure of selected atoms and molecules in vapor phase. Electron spectroscopy is applied for studying the electronic transitions following excitation and ionization with electron and photon bombardment. The work focuses on the photoionization and Auger decay of selected noble gasses, and on the photoionization and Auger decay of core ionized or resonant excited alkali halide molecules. The experimental results are compared with theoretical predictions.

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19

Napier, Stuart A. "Electron correlation and spin-dependent effects in the electron impact excitation of zinc atoms". University of Western Australia. School of Physics, 2009. http://theses.library.uwa.edu.au/adt-WU2009.0098.

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[Truncated abstract] This work investigated electron correlation and spin-dependent effects in electron scattering from zinc for incident electron energies from the lowest excitation threshold at 4.003 eV to 50 eV. Experiments were performed using a crossed-beams electron impact spectrometer, which included an unpolarised electron gun, and also a spin-polarised electron gun. The apparatus was tested, and shown to be operating well, by repeating past studies of electron scattering from helium and argon. Emission cross sections for the 4s4p 3P1, 4s4p 1P1, 4s5s 3S1, 4s4d; 5d; 6d 3D1;2;3 and 4s4d; 5d 1D2 states were measured from the respective thresholds to 50 eV. These were compared with Convergent Close-Coupling (CCC) and B-spline R-matrix (BSRM) calculations of the 4s4p 3P1, 4s4p 1P1, 4s5s 3S1, 4s4d 1D2 and 4s4d 3D1;2;3 emission cross sections. There are serious discrepancies between the theories, and between the theories and experiment, which indicates strong continuum coupling and innershell excitation effects in the electron excitation of zinc. The differential elastic scattering signal at scattering angles of 30 , 54 , 90 and 110 was measured for incident electron energies from just below the lowest excitation threshold at 4.003 eV, to the ionisation threshold at 9.394 eV. Some assignments given by Sullivan et al [1] and Zatsarinny and Bartschat [2] were confirmed by the present experiment. An area of disagreement in the literature concerning the nature of a feature observed at the 4s4p 1P1 threshold at 5.796 eV was resolved in favour of Zatsarinny and Bartschat, who assign the feature as a cusp. ... Below the ionisation threshold, the 4s4p 3P1 photon excitation function supports the assignment of the near-4s4p 1P1 threshold feature as a cusp. Some of the overlapping negative-ion resonances which were observed near 7.5 eV in the 4s4p 3P1, 4s4p 1P1 and 4s5s 3S1 photon excitation functions were assigned with the assistance of the BSRM calculations of Zatsarinny and Bartschat. However, continuum coupling effects above 8 eV seem to cause the theoretical negative-ion resonance predictions to break down. Above the ionisation threshold, the near-11 eV negative-ion resonance effects depend on the configuration n, L and S of the neutral state excitation observed. This may be due to the properties of the mixed negative ion component states. Postcollision interaction (PCI) effects the 4s5s 3S1, 4s4d; 5d; 6d 3D1;2;3 and 4s4d; 5d 1D2 photon excitation functions. The PCI mechanism can populate the 4s4d; 5d; 6d 3D1;2;3 and 4s4d; 5d 1D2 states because the scattered and ejected electrons have a similar energy, and can thus exchange a large amount of orbital angular momentum. The present work demonstrates that electron correlation effects, especially those associated with innershell excitation, are very significant in electron scattering from zinc. Existing theoretical models of electron scattering from zinc inadequately treat electron correlations, and as a result of this are inaccurate, as shown here. The studies presented here should guide the development of models that accurately describe the innershell excitation effects, which are important for zinc and a great many other atoms.

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20

Giebels, Franz-Josef [Verfasser], i Roland [Akademischer Betreuer] Feder. "Emission of electron-electron and electron-positron pairs from solid surfaces due to electron or positron impact / Franz-Josef Giebels. Betreuer: Roland Feder". Duisburg, 2015. http://d-nb.info/1075456193/34.

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21

Skoglund, Lindberg Peter Anders. "Electron-Impact Liquid-Jet Water-Window X-ray Sources". Licentiate thesis, KTH, Biomedicinsk fysik och röntgenfysik, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-28622.

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This Thesis describes the development and characterization of a soft x-ray liquidjet-anode electron-impact source. With a water-jet target the primary emission is the O Kα line at 525 eV. This is close to the lower edge of the water-window, a spectral region lacking simple laboratory sources. In the hard x-ray regime electronimpact microfocus sources have matured and are simple, stable, reliable, and inexpensive. It would be beneficial if this source concept could be used also for soft x-ray generation. Spectral measurements of a 120 W, 30 keV electron beam focused on a 20 μm water jet show an x-ray intensity of up to 3.2 × 1012 ph/(s×sr×line). Combined with source size measurements up to 50 W a maximum brightness of 3.5 × 109 ph/(s×μm2×sr×line) is reported. This makes the brightness comparable to the compact discharge-plasma sources presently used for soft x-ray microscopy. The source appears to be scalable another order of magnitude which would make the brightness equal to that of the laser-plasma sources.
QC 20110119

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22

Eves, Brian John. "Polarized fluorescence by the electron impact excitation of atoms". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape15/PQDD_0003/MQ32104.pdf.

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23

Harb, Tarek Hussein. "Laser Induced Fluorescence studies of water by electron impact". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape11/PQDD_0012/MQ52562.pdf.

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24

Duffy, Christopher James. "Modeling hot-electron injection and impact ionization in pFET's". Thesis, Georgia Institute of Technology, 2001. http://hdl.handle.net/1853/14796.

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25

Bass, A. D. "Negative ion resonances seen in electron impact excitation functions". Thesis, University of Manchester, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.234196.

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26

Roche, Peter John Patrick. "On the theory of electron and photon impact ionisation". Thesis, University of Cambridge, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.615231.

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27

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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28

Bostwick, Aaron A. "Impact on calcium fluoride reactivity and electronic structure of photon and electron stimulated fluorine desorption /". Thesis, Connect to this title online; UW restricted, 2004. http://hdl.handle.net/1773/9721.

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29

Kam, Kin Fai. "Theoretical studies of atomic and quasiatomic excitations by electron and ion impact". Thesis, University of York, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.311088.

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30

McLaughlin, Damien T. "Polarisation correlation studies of the 3D states of helium". Thesis, Queen's University Belfast, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.317514.

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31

Cooper, Helen Jill. "Mass spectrometric studies of collisional activation and target capture". Thesis, University of Warwick, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.245936.

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32

Currell, F. J. "A study of vibrational excitation of molecules via negative ion resonances". Thesis, University of Manchester, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.382748.

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33

Borovik, Alexander [Verfasser]. "Electron-impact ionization of xenon and tin ions / Alexander Borovik". Gießen : Universitätsbibliothek, 2011. http://d-nb.info/1063177561/34.

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34

Aitken, Craig George. "Electron impact ionisation of molecular clusters and spatially oriented molecules". Thesis, University of Canterbury. Chemistry, 1995. http://hdl.handle.net/10092/7613.

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A pulsed supersonic molecular beam apparatus has been used to determine the appearance energies of the cluster ions (CO₂)n+ (2≤n≤4), (N₂O)n+ (2≤n≤4), (NH₃)nNH⁺₄ (0≤n≤7) and the cluster ion fragments (N₂O.O)⁺ and (N₂O.NO)⁺ by electron impact ionisation. The measured appearance energies were used to estimate cluster ion binding energies and to deduce possible mechanisms for the formation of the cluster fragment ions (N₂O.O)⁺ and (N₂O.NO)⁺. A discussion is given on the transformation of the molecular beam machine to accommodate the study of electron impact ionisation of spatially oriented molecules. Characterisation of the inhomogeneous electrostatic hexapole field is described. Electron impact ionisation asymmetry results were measured for CH₃Cl, CH₃Br, CF₃Br and CHCl₃ using a quadrupole mass spectrometer and mass insensitive rotatable particle multiplier. Measurement of the asymmetry effect for formation of the molecular ions CH₃Cr, CH₃Br⁺ and the fragment ions CH₃+ from CH₃Cl and CH₃Br, CF₃⁺ from CF₃Br and CHCl₂+ from CHCl₃ are determined and discussed. Each molecule showed a preference for electron impact to occur at the positive end of the molecule. The effect of hexapole voltage and electron energy on the asymmetry effect is also discussed. A simple model is presented for electron impact ionisation at either end of a molecule which accounts qualitatively with the asymmetry results determined.

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35

Brown, Derek Oliver. "Angular correlation studies for electron impact excitation of atomic magnesium". Thesis, University of Newcastle Upon Tyne, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.401850.

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36

Warner, C. D. "The excitation of atomic hydrogen by high resolution electron impact". Thesis, University of Manchester, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.356717.

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37

Harrison, I. "Excitation of inner-shell states of molecules by electron impact". Thesis, University of Manchester, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.375070.

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38

CORDARO, RICHARD BRIAN. "ELECTRON IMPACT DISSOCIATIVE IONIZATION OF HYDROGEN, WATER, AND HYDROGEN SULFIDE". Diss., The University of Arizona, 1985. http://hdl.handle.net/10150/188028.

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The dissociative ionization by electron impact of H₂, H₂O, and H₂S was investigated between the electron impact energies of 20 and 45 eV. Protons were the detected fragments, and a time-of-flight method was used to measure the proton kinetic energies. By also measuring the thresholds for the production of discrete energy groups of protons, it was possible to determine the dissociation limits and kinetic energy distributions for individual electronic states. It was found that autoionizing states that lead to dissociation were the major contributors of proton fragments for all of the molecules investigated. Some of the measurements are tabulated in the following table. (UNFORMATTED TABLE FOLLOWS) Molecule Threshold Dissociation Probable Probable (eV) limit (eV) state fragments H₂ 24.5±1.0 18.0±1.0 Q₁ ¹Σ(g)⁺ H⁺, H(1S) 30.5±1.0 18.0±1.0 Q₁ ¹Πᵤ H⁺, H(1S) 36.5±1.0 -- ²Πᵤ H⁺, H(2P) H₂O 24.5±1.0 19.5±1.0 -- H⁺, OH (X²Π) 29.5±1.0 23.0±1.0 -- H⁺,O(³P),H(1S) H₂S 25.5±1.0 18.0±1.0 -- H⁺, HS (X²Π) 32.0±1.0 -- -- H⁺, . . . 42.0±1.0 -- -- H⁺, . . . (TABLE ENDS)

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39

Guerra, Mauro António Moreira. "Electron impact ionization cross sections and analysis of X-ray spectra". Doctoral thesis, Faculdade de Ciências e Tecnologia, 2012. http://hdl.handle.net/10362/9141.

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40

Eden, Samuel Peter. "Spectroscopic and electron impact studies of molecules relevant to plasma etching". Thesis, University College London (University of London), 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.407575.

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Hirt, Benjamin David. "Impact of Additives on Thermionic Cathodes". Ohio University Honors Tutorial College / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=ouhonors1524832507214002.

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Bart, Mark. "Electron impact ionization: Measurements of absolute cross-sections and cross-beam studies". Thesis, University of Canterbury. Chemistry, 2003. http://hdl.handle.net/10092/5712.

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Absolute total electron impact ionization cross-sections have been measured and calculations performed for C1 to C4 perfluorocarbons, C1 to C5 chlorocarbons and a number of mixed halo carbons and nitriles. Measured and calculated cross-sections using several different models have been analyzed using empirically and theoretically determined functions in terms of fundamental molecular parameters. A series of bond contributions to the total electron impact ionization cross-section have been determined and shown to reproduce total cross-sections for all of the molecules investigated with a high degree of confidence. An instrument has been constructed for the measurement of pseudo-absolute partial electron impact ionization cross-sections using the NIST standard mass spectrum database as a reference. Measurements were carried out for CF4, C2F6, C3F8, C3F6, F2C=CF-CF=CF2 and F3C-C=C-CF3 Theoretical models of electron impact ionization cross-sections have been critically assessed and a correction factor has been devised and applied to the binary encounter Bethe model of electron impact ionization resulting in a significant improvement in the performance of that model such that it can now be used for molecules comprising of atoms in rows 1 to 4 of the periodic table with a high degree of confidence. Ion imaging has been applied for the first time to crossed-beam electron impact ionization in an attempt to measure angular scattering patterns and energy disposal in a one step process. The instrument and the ion imaging process are described in detail and preliminary results reported in this thesis. A feasibility study has been carried out on the use of a capacitance manometer to measure neutral molecular beam fluxes directly and recommendations made for the future development of a usable device.

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Gough, Sean F. "The shape of excited krypton atomic states produced by low energy electron impact". Thesis, Queen's University Belfast, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.334528.

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Bekx, John Jasper [Verfasser]. "Towards modeling of electron-impact ionization in warm dense matter / John Jasper Bekx". Hamburg : Staats- und Universitätsbibliothek Hamburg Carl von Ossietzky, 2020. http://nbn-resolving.de/urn:nbn:de:gbv:18-ediss-88839.

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Peng, Fei. "Structure determination of beam sensitive crystals by rotation electron diffraction : the impact of sample cooling". Doctoral thesis, Stockholms universitet, Institutionen för material- och miljökemi (MMK), 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-145636.

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Electron crystallography is complementary to X-ray crystallography. Single crystal X-ray diffraction requires the size of a crystal to be larger than about 5 × 5 × 5 μm3 while a TEM allows a million times smaller crystals being studied. This advantage of electron crystallography has been used to solve new structures of small crystals. One method which has been used to collect electron diffraction data is rotation electron diffraction (RED) developed at Stockholm University. The RED method combines the goniometer tilt and beam tilt in a TEM to achieve 3D electron diffraction data. Using a high angle tilt sample holder, RED data can be collected to cover a tilt range of up to 140o. Here the crystal structures of several different compounds have been determined using RED. The structure of needle-like crystals on the surface of NiMH particles was solved as La(OH)2. A structure model of metal-organic layers has been built based on RED data. A 3D MOF structure was solved from RED data. Two halide perovskite structures and two newly synthesized aluminophosphate structures were solved. For those beam sensitive crystals characterized here, sample cooling down to -170oC was used to reduce the beam damage. The low temperature not only reduces electron beam damage, but also keeps the structure more stable in the high vacuum in a TEM and improves the quality of the diffraction data. It is shown that cooling can improve the resolution of diffraction data for MOFs and zeolites, for samples undergoing phase changes at low temperature, the data quality could be worse by cooling. In summary, cooling can improve the ED data quality as long as the low temperature does not trigger structural changes.

At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 1: Manuscript. Paper 3: Submitted.

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Pflüger, Thomas [Verfasser], i Alexander [Akademischer Betreuer] Dorn. "Electron Impact Ionization Studies of Small Rare Gas Clusters / Thomas Pflüger ; Betreuer: Alexander Dorn". Heidelberg : Universitätsbibliothek Heidelberg, 2012. http://d-nb.info/1179784472/34.

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Jayanty, Vivi. "Miniaturized electron-impact-ionization pumps using double-gated isolated vertically aligned carbon nanotube arrays". Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/75659.

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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2012.
Cataloged from PDF version of thesis.
Includes bibliographical references (p. 67-71).
There is a need for microscale vacuum pumps that can be readily integrated with other MEMS and electronic components at the chip-scale level. Miniaturized ion pumps exhibit favorable scaling down because they are surface-limited and miniaturization increases the ratio between the active surface and the chamber volume, resulting in enhanced ionization and pump rates. Therefore, scaled-down ion pumps are a promising choice for a variety of applications including portable mass spectrometers and sub-mm wavelength vacuum amplifiers. Our micropump architecture consist of a field-emission electron source that is an array of double-gated isolated vertically aligned carbon nanotubes (VA-CNTs), an electronimpact- ionization region, and a non-evaporative ion-implantation getter. Single-gated VA-CNT FEAs were tested as field emitters in high vacuum (10-9 Torr). The current density of the tested device is ~0.5A/cm2 (total current of 0.4mA) and a field enhancement factor of 1.41 x106 V/cm was measured, which is comparable to the simulation results by COMSOL. Two ways to fabricate double-gated VA-CNT FEAs were reported: one has the focus gate in plane with the extractor gate and the other has the focus gate above the extractor gate. Due to problems on fabrication process of double-gated VA-CNTs (short circuit between emitters, extractor gate, and focus gate), we were not able to collect four-terminal measurement, electron-impact-ionization, and pump data. However, procedure on how to collect and analyze field emission data with two gates to find [beta]G and [beta]F was described. In addition, procedures on how to collect and analyze data on electron impact ionization pump were also presented.
by Vivi Jayanty.
S.M.

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Bush, Nathan L. "The impact of radiation damage on electron multiplying CCD technology for the WFIRST coronagraph". Thesis, Open University, 2018. http://oro.open.ac.uk/55053/.

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This thesis follows an investigation into the effects of radiation damage on the e2v CCD201-20; the detector baselined for use in the WFIRST coronagraph imaging and spectroscopy camera systems (hereafter, WFIRST CGI). The CCD201 is an EM-CCD, a variant of traditional CCD technology that is well suited for operation in light starved conditions. Despite successful implementation on many ground-based instruments, the technology has yet to be used within a space environment and therefore has low technological maturity compared to the standard CCD counterpart. Improvement of the technological maturity rested upon in-depth investigations into the effect of radiation damage on the CCD201, which in turn could be used to estimate the End Of Life (EOL) performance of the instrument and de-risk the utilisation of EM-CCDs for the mission. An in-depth radiation campaign was completed whereby multiple CCD201s were irradiated to multiple fluence levels at both room temperature and the nominal operating temperature of the mission (165 K). Performance was measured prior to and following each irradiation, including measurements of low-signal Charge Transfer Inefficiency (CTI), dark current and Clock Induced Charge (CIC). Significant performance differences were noted between the room temperature and cryogenic irradiation case, indicating that cryogenic irradiations are instrumental to accurate EOL performance estimates. CTI was identified as the key limitation to CGI science performance, and so attention then turned to amelioration strategies focused on improving performance in the presence of radiation damage, including trap pumping and narrow-channel modelling. The results presented in this thesis have helped lead to the adoption of the CCD201-20 for the WFIRST mission, have provided key insight into the differences between room temperature and cryogenic irradiations, have advanced the “trap pumping” technique for use on EM-CCDs and presented the properties on the dominant traps that impact CTI for radiation damaged CCDs. The findings are not only useful for the WFIRST CGI, but for any future space mission that will utilise EM-CCD technology in an environment where radiation has the potential to degrade science performance.

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Travia, Anderson Dingfelder Michael. "Interaction cross sections needed for simulation of secondary electron emission spectra from thin metal foils after fast proton impact". [Greenville, N.C.] : East Carolina University, 2009. http://hdl.handle.net/10342/1906.

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Thesis (M.S.)--East Carolina University, 2009.
Presented to the faculty of the Department of Physics. Advisor: Michael Dingfelder. Title from PDF t.p. (viewed Apr. 23, 2010). Includes bibliographical references.

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Richardson, Letetia M. "Theoretical studies of oscillator strengths and electron impact excitation cross sections of singly ionized oxygen". DigitalCommons@Robert W. Woodruff Library, Atlanta University Center, 1998. http://digitalcommons.auctr.edu/dissertations/2304.

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We considered the lowest twenty-eight LS states of singly ionized oxygen in our calculations of excitation energies, oscillator strengths, transition probabilities, radiative life-times, and electron collisional excitation cross sections. Transition probabilities and oscillator strengths were calculated by the use of a configuration-interaction method and the electron impact excitation collision strengths were calculated in the close-coupling approximation using the R-matrix method. The LS states of singly ionized oxygen are represented by extensive configuration-interaction wave functions that give excitation energies in close agreement with the experimental values. Rydberg series of resonances converging to the excited state thresholds are explicitly included and are found to make substantial enhancements in the cross sections for many transitions. The electron impact excitation of oxygen ions is a dominant excitation atomic process in the Jupiter's satellite Io plasma torus and several other astrophysical plasmas. Our research has helped us to understand further the basic aspects of atomic structure and atomic collisional processes.

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