The electronic emission spectra of the CO molecule in an applied electric field of 53.8 kilovolts/cm has been observed. The electric field was determined from the Stark Effect on the H line at 4340Å. The spectra were produced in the high field region of a low pressure glow discharge using carbon monoxide gas and water vapour. The electric dipole moment of the CO molecule has been determined for the BlΣ+ state using the P(l) transition of the Ångstrom ( 0 , 0 ) band. The effect observed is a second order effect in the B1Σ+ state and it has been deduced that the dipole moment of the A1π state is very small or zero. The dipole moment of the B1Σ+ state is 1.61 debye ± 14%. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

The binding energies and momentum profiles for each of the valence orbitals of CO and H₂S have been measured by high momentum resolution electron momentum spectroscopy. The experimental momentum profiles are compared on a quantitative basis within the Target Hartree-Fock Approximation to theoretical calculations using SCF wavefunctions ranging in quality from minimal basis to Hartree-Fock limit. Calculated momentum distributions for the 5σ orbital of CO are shown to be very basis set dependant while calculated momentum distributions of the CO 3σ, 4σ and 1π orbitals change very little with improvements in the wavefunction beyond the double-zeta level. The CO 1π orbital is not very well described in the low momentum region even at the Hartree-Fock limit with basis set saturation including diffuse functions. While the 4a₁, and 2b₂ momentum profiles of H₂S are well described using even minimal basis calculations, diffuse functions must be included in the basis set to describe the 2b₁, and 5a₁, momentum profiles. The experimental momentum profiles of H₂S are also compared with full ion-neutral overlap calculations incorporating correlation in the ground state and correlation and relaxation in the final ion state. These calculations are very similar to the Hartree-Fock level momentum distributions, indicating that correlation is not very important in describing the momentum profiles of H₂S. The binding energy spectra and momentum profiles of the inner valence region of both CO and H₂S are studied in detail. Peaks in the CO binding energy spectrum at 24.1 and 28.3 eV are assigned as satellites 4σ and 1π main lines respectively while the structure above 30 eV is shown to be predominantly due to satellites of the 3σ orbital. The intense structure in the inner valence region of H₂S is found to arise predominantly from the 4a₁, orbital. The assignments of the inner valence spectra of both molecules is confirmed within experimental uncertainties by the spectroscopic sum rule. / Science, Faculty of / Chemistry, Department of / Graduate

Yan, Lei. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2007. / Includes bibliographical references (leaves 50-52). / Abstracts in English and Chinese. / Title Page --- p.I / Thesis Committee --- p.II / Abstract --- p.III / 摘要 --- p.IV / Acknowledgements --- p.V / Table of Contents --- p.1 / Chapter Chapter I. --- Introduction --- p.3 / Chapter Chapter II. --- Properties of Hydrogen --- p.6 / Chapter A. --- Spectroscopic Properties of Hydrogen Molecules --- p.6 / Chapter B. --- Properties of Solid Hydrogen --- p.9 / Chapter C. --- Solid Hydrogen as a Matrix Material --- p.12 / Chapter Chapter III. --- Experimental Apparatus --- p.16 / Chapter A. --- Fourier Transformer Spectrometer --- p.16 / Chapter B. --- Cryostat and Sample Cell --- p.23 / Chapter C. --- Gas Handling System and ortho-para Converter --- p.25 / Chapter D. --- Determination of o-H2 Concentration --- p.29 / Chapter E. --- Preparation of Matrix-isolated Species --- p.32 / Chapter Chapter IV. --- Spectroscopic studies of CO in solid hydrogen --- p.34 / Chapter A. --- "Matrix Isolation Spectroscopy of CO, brief overview" --- p.34 / Chapter B. --- Observation and Preliminary Analysis --- p.35 / Chapter i. --- CO in Normal H2 Matrix --- p.35 / Chapter ii. --- CO in Hydrogen Matrix of 50/50 Mixture --- p.37 / Chapter iii. --- CO in Para-enriched Solid Matrix --- p.39 / Chapter C. --- Discussion --- p.46 / Chapter Chapter V. --- Concluding Remarks --- p.48 / Reference --- p.50

The development and implementation of a high resolution, direct absorption, rapidscanning infrared diode laser spectrometer incorporating a supersonic jet expansion source is described. High sensitivity is achieved by directly modulating absorption signals at frequencies in excess of 50 kHz, enabling their separation from lower frequency mechanical and diode 1/f noise. This is accomplished by rapidly scanning the diode laser across a small frequency window (~0.5-1.5cm^-1) synchronously with a pulsed supersonic expansion in a time period of 1 or 2 ms. Absorptions appear as small attenuations in the overall variation of the laser mode power across the scan window. This background profile is removed by recording the laser power without gas pulsing and subtracting. Relative frequency calibration is effected by simultaneously recording the spectrum of a reference gas and the interference fringes of an etalon. Absorption signals are recorded by means of a fast 12-bit analog-to-digital converter operating at 1 MHz. This is housed within a dedicated PC microprocessor which performs spectrometer control, data coaddition, signal processing and spectrum calibration functions. The spectrometer has been used to measure the infrared spectra of two weakly bound complexes, CO-OCS and Ne-SiH₄. The infrared absorption spectrum of CO-OCS was measured in the 5μm region of the OCS ν₃ asymmetric stretch. In addition microwave spectra of CO-OCS and two isotopomers ¹³CO-OCS and CO-OC³⁴S have been recorded using a pulsed nozzle microwave Fourier transform spectrometer. The lines have been fitted to a Watson S reduction Hamiltonian yielding rotational, quartic and (for the ground states) sextic centrifugal distortion constants. A T-shaped structure is determined and this is rationalised by a simple potential model incorporating a distributed multipole analysis of the electrostatic charge distribution, distributed dispersion contribution and a cylindrical hard-core repulsion. The infrared spectrum of Ne-SiH4 was recorded in the vicinity of the SiH₄ ν₃ triply degenerate stretching vibration centred at 2189.19 cm^-1. Ne-SiH₄ is only the second atomspherical top complex to be successfully recorded and analysed. The complex exhibits an intermolecular potential with considerably smaller anisotropy than its argon analogue Ar-SiH₄. Consequently the SiH₄ unit is almost free to rotate within the complex, resulting in novel Coriolis interaction between the angular momentum of the SiH₄ unit and that of the overall complex. Individual bands are fitted to Coriolis interaction Hamiltonians, and the band centres for all the transitions of the complex are fitted to an anisotropic intermolecular potential. Finally, applications of the spectrometer to the study of air sensitive compounds and species generated by electric discharge sources are considered.

The behavior of adsorbed carbon monoxide on platinum was studied using potential difference infrared spectroscopy. Three solvents and three electrolytes were chosen, and data gathered at both high and low adsorbate coverages. The rate of change of IR peak position with applied potential, the Stark tuning rate, was used as an indicator of the local electric field strength at the interface. It was determined that neither solvated cation size nor bulk dielectric constant accounts for the changes in Stark tuning rate with different solvents. / Master of Science