No description available.

No abstract available. / Thesis (PhD)--University of Pretoria, 2010. / Physics / unrestricted

No description available.

The main idea of this paper is inspired by a paper written together by my advisor Dr. Hang, Dr. Huang of the Industrial Technology Research Institute, and Dr. Chao of Institute of Applied Mechanics of National Taiwan University[quant-ph/0506153 v1,2005]. After some mathematical calculations we can extend the WKB approximation to treat position-dependent effective mass problem (PDEM). Then we did simulation on a model PDEM problem to compare the well-know closed form solution and the extended WKB approximation. We demonstrated that the extended WKB approximation not only can obtain the eigenvalues very accurately, but also is very useful to estimate the distribution of the wave function. We also found the modulation on the oscillations of wave function under PDEM by the extended WKB approximation.

<p> Various low-lying electronic states of formaldehyde and acetone have been investigated, using molecular orbital calculations, to determine their involvement in the photochemical system. The potential energy surfaces of these states were calculated using the CND0/2. </p> <p> The results of this study show that the decomposition of formaldehyde to molecular products H2 and CO (process II) occurs via the ground state; the potential surface of this process was studied using configuration interaction methods. </p> <p> The process leading to radical products in both acetone and formaldehyde (process I) can arise either directly from the singlet and triplet (n,π*) states via a reaction path of no symmetry, or by crossing to the 3 (π,π*) state should Cs symmetry be maintained. The ground state is the only other state correlating with radical products. </p> / Thesis / Master of Science (MSc)

No description available.

京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第19957号 / 理博第4224号 / 新制||理||1607(附属図書館) / 33053 / 京都大学大学院理学研究科化学専攻 / (主査)教授 北川 宏, 教授 島川 祐一, 教授 竹腰 清乃理 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM

A series of 2,5-diarylidene-cyclopentanones (ndbcp), their protonated cations (ndbcp-H+), and a substituted compound, 2,5-bis-[3-(4-dimethylamino-phenyl)-allylidene-cyclopentanone (2dbma) have been synthesized. Their electronic absorption and fluorescence spectra have been measured. The absorption spectra have been assigned with the aid of INDO/S calculations. Molecular structures used for the INDO/S calculations were computed with the PM3 Hamiltonian. Polarized excitation spectra have been measured for 2dbcp and 3dbcp at 77 K in ethanol/methanol glass and used as an aid for the assignments of electronic transitions. Absorption and fluorescence spectra have been measured in solvents of varying polarity for all compounds synthesized. The influence of hydrogen bonding on the excitation spectra of compounds has been investigated. Solvent induced shifts in the absorption and fluorescence spectra of 3dbcp and 2dbma in combination with the PM3 calculated ground state dipole moment have been used to determine the excited state dipole moment of these compounds. Fluorescence quantum yields have been obtained to analyze the changes in the nonradiative rate of decay from S1. The protonated cations have been prepared in acids of different strength. The influence of acid strength on the excitation and emission spectra has been analyzed by gradually diluting acid solution. Evidence for excited state proton transfer in weak acids has been obtained for 2dbcp and 3dbcp. Brief photochemical studies of 1dbcp and 1dbcp-H+ have been carried out and analyzed by HPLC.

No description available.

Radicals are interesting to study because of importance in so many processes such as semiconductor growth or stellar evolution. Laser induced fluorescence (LIF) and wavelength resolved emission spectra of jet cooled HPS, HAsO, AsD2, H2PS, and F2BO have been measured using the pulsed discharge jet technique. Several bands in the à 1A′′ − X̃ 1A′ transition of HPS were observed and assigned with the help of ab initio calculations. The ab initio geometries showed that HPS does not follow Walsh’s predictions for the angle change upon electronic excitation; Walsh predicts an increase in HPS upon excitation while a decrease is calculated. Ab initio Walsh-style orbital angular correlation diagrams for both electronic states show a change in correlation for some orbitals upon electronic excitation, an effect that Walsh did not predict. The à 1A′′ − X̃ 1A′ transitions were measured in HAsO and DAsO for the first time. A molecular geometry was derived for each electronic state from experimental rotational constants. The experimental geometries prove that HAsO also violates Walsh’s rules for the same reason shown in HPS. The à 2A1 – X̃ 2B1 electronic transition of AsD2 and AsHD were measured. Vibrational levels observed in emission were fit to a local mode vibrational Hamiltonian. Using the previously reported rotational constants for AsH2 and those determined for AsD2 in this work, an improved estimate of the excited state geometry was obtained. The discovery of the B̃ 2A′ − X̃ 2A′ band system of H2PS is the first report of this molecule. Both D2PS and HDPS were also observed. Ab initio calculations helped assign the transition. H2PS is one of the few tetra-atomic or larger molecules that violates Kasha’s empirical rule due to the large separation between the B̃ and à states. Finally, laser induced fluorescence spectra of the F2BO radical was observed for the first time. Previous work showed two band systems with only a tentative assignment. The measured LIF spectra confirm the identity of the two band systems as the B̃ 2A1 – X̃ 2B2 and the B̃ 2A1 – à 2B1 transitions showing F2BO also violates Kasha’s rule.