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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Zero field level crossing in molecular hydrogen

Van der Linde, Jacob January 1970 (has links)
The lifetimes of the 3d¹Σ(v=0) J = l, 2 and 3 states have been measured using zero-field level crossing techniques. The transitions observed were the R-branch members of the 3d¹Σ ↦ 2p¹Σ transition. The upper state is excited in a discharge between two capacitor plates to which a radio-frequency voltage is applied. The measurements were made using first a 180 MHz R.F. source and later using a 450 MHz source. Polarization of emitted light was measured by rotating a polaroid in the beam and phase sensitive detecting the resulting modulation. The depolarization curves obtained by plotting the magnetic field strength against the polarization of the R(0), R(l), R(2) lines yield halfwidths, when extrapolated to zero pressure, of 2.37±.12 gauss, 2.60±.15 gauss and 3.25±.25 gauss. The halfwidths vary linearly with pressure in the discharge cell yielding collision cross-sections of roughly 1.5x10⁻¹⁴ cm². Using the high field Landé g values of these states, their lifetimes are (2.66±.12)x10⁻⁸sec., (3.83±.2)x10⁻⁸sec., and (3.93±.25)x10⁻⁸sec. for J=l, 2 and 3 respectively. The discrepancy between the first and the latter two lifetimes is discussed. / Science, Faculty of / Physics and Astronomy, Department of / Graduate
12

Magnetic resonance studies of atomic hydrogen confined by solid molecular hydrogen between 6.4 and 8.2 k

Steel, Stephen Chris January 1985 (has links)
Magnetic hyperfine resonance in zero magnetic field has been used to study atomic hydrogen gas confined by walls coated with solid molecular hydrogen at temperatures between 6.4 and 8.2 K. The temperature range of the experiments was limited by the nature of the atom source used to produce atoms. Measurements of the frequency shift at low atom densities (nH ≃ 8 x l0⁺¹⁶ m⁻³) have yielded a binding energy for H on H₂ of 34.04 ± 0.26 K, and a surface frequency shift of -1.16 ± 0.05 MHz. These results are in excellent agreement with those obtained by Crampton et al between 3.2 and 4.5 K. The pressure shift due to the vapour pressure of the solid H₂ was found to be -1.78 ± 0.01 x 10⁻²⁴ Hz m³. The low atom density transverse relaxation rate measurements are difficult to interpret. There seems to be a relaxation mechanism on the H₂ surface that gives a contribution beyond that associated with the dispersion of frequency shifts an atoms see from normal adsorption. The data does show that the sticking coefficent of H on H₂ is greater than 0.04. Measurements at higher atom densities (nH ≤ 9 x 10⁺¹⁸ m⁻³) gave values for the surface recombination cross length which increased from 0.5 A at 6.4 K to 1.1 A at 8.2 K. The bulk spin exchange cross section was found to agree quite well with the calculations of Berlinsky and Shizgal. / Science, Faculty of / Physics and Astronomy, Department of / Graduate
13

Hydrogen embrittlement susceptibility of cold drawn plain carbon steel wires

Erdemir, Ali 12 1900 (has links)
No description available.
14

Life-cycle environmental assessment of the nuclear production of hydrogen using the sulfur-iodine cycle /

Lattin, William C. January 1900 (has links)
Thesis (Ph. D., Environmental Science)--University of Idaho, July 2008. / Major professor: Vivek P. Utgikar. Includes bibliographical references (leaves 108-120). Also available online (PDF file) by subscription or by purchasing the individual file.
15

Radiative decays of hydrogenic states in a magnetic field /

Lev, Bogdan. January 2008 (has links)
Thesis (M.Sc.)--York University, 2008. Graduate Programme in Physics and Astronomy. / Typescript. Includes bibliographical references (leaves 55-56). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:MR38798
16

Some properties of solid hydrogen at small molar volumes

Ahlers, Guenter. January 1963 (has links)
Thesis (Ph.D.)--University of California, Berkeley, 1963. / "UC-4 Chemistry" -t.p. "TID-4500 (24th Ed.)" -t.p. Includes bibliographical references (p. 131-133).
17

Models for intramolecular hydrogen bonds involving polar C-H groups

李全, Li, Chuen. January 1982 (has links)
published_or_final_version / Chemistry / Doctoral / Doctor of Philosophy
18

Laser spectroscopy of biologically-related molecules and their hydrated clusters

Hockridge, Matthew Richard January 1999 (has links)
No description available.
19

Theoretical investigation of three-centered hydrogen bonds in DNA-DFT and NBO studies.

January 2003 (has links)
Sze Chun Ngai. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2003. / Includes bibliographical references (leaves 71-75). / Abstracts in English and Chinese. / ABSTRACT --- p.iii / ACKNOWLEDGEMENTS --- p.vii / Chapter CHAPTER ONE: --- INTRODUCTION AND BACKGROUND --- p.1 / Chapter 1.1 --- Introduction --- p.1 / Chapter 1.2 --- Definitions of Hydrogen Bonds (H-bonds) --- p.1 / Chapter 1.3 --- Experimental Evidences of Hydrogen Bonding --- p.3 / Chapter 1.4 --- Three-Centered H-bonds --- p.5 / Chapter 1.5 --- Scope of the Thesis --- p.6 / Chapter CHAPTER TWO: --- THEORY AND COMPUTATIONAL DETAILS --- p.8 / Chapter 2.1 --- Introduction --- p.8 / Chapter 2.2 --- Theory --- p.9 / Chapter 2.2.1 --- Density Functional Theory (DFT) --- p.9 / Chapter 2.2.2 --- Chemical Shifts --- p.10 / Chapter 2.2.3 --- Spin-Spin Coupling Constants --- p.11 / Chapter 2.2.4 --- Natural Bond Orbital (NBO) Analysis --- p.13 / Chapter 2.3 --- Methodology --- p.16 / Chapter 2.3.1 --- Geometry Optimization --- p.16 / Chapter 2.3.2 --- Nuclear Magnetic Resonance (NMR) Properties --- p.21 / Chapter 2.3.3 --- NBO Analysis --- p.22 / Chapter 2.4 --- Geometry Optimization --- p.23 / Chapter 2.5 --- Summary --- p.29 / Chapter CHAPTER THREE: --- RESULTS AND DISCUSSION --- p.30 / Chapter 3.1 --- Introduction --- p.30 / Chapter 3.2 --- Comparison of Computed Results with X-ray Crystallography Data --- p.30 / Chapter 3.3 --- NMR properties --- p.33 / Chapter 3.3.1 --- Chemical Shifts --- p.33 / Chapter 3.3.2 --- Spin-Spin Coupling Constants --- p.38 / Chapter 3.4 --- Natural Bond Orbital (NBO) Analysis --- p.41 / Chapter 3.4.1 --- Determination of Three-centered H-bonds --- p.41 / Chapter 3.4.2 --- NBO Analysis of Different Interaction of Dimer Units --- p.43 / Chapter 3.4.3 --- Detailed Analysis of CC and CG Dimers --- p.64 / Chapter 3.5 --- Summary --- p.68 / Chapter CHAPTER FOUR: --- CONCLUDING REMARKS --- p.69 / REFERENCES --- p.71 / APPENDIX --- p.76
20

Thermodynamic Analysis of Hydrogen Generation

Buford, Clarence Marcelle 26 November 2003 (has links)
Hydrogen is an energy carrier that can be used to create electricity via an electrochemical device called a fuel cell. Thus, many American scientists and policy makers consider hydrogen to be the fuel of the future because it can be produced without depending on petroleum imports. The research described in this dissertation investigates a thermodynamic model to predict results from and to compare methods of producing hydrogen. Hydrogen generation will be explored through modeling two types of processes: steam reforming and supersonic pyrolysis. Results of the model predict that although methanol is a widely used fuel for steam reforming, dimethyl ether can produce the same amount of hydrogen when it is reformed while consuming less energy. Supersonic pyrolysis is a well known process but has only recently been considered as a route to produce hydrogen. The model shows that pyrolysis could be a good alternative to steam reforming. Pyrolysis of fuels occurs at higher temperatures than does steam reforming and hence a higher energy input is necessary, however, hydrogen can be produced ten times faster making pyrolysis a more powerful method to produce hydrogen.

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