Neste trabalho, métodos ab initio multiconfiguracionais de alto nível com extenso conjunto base e inclusão de correções relativísticas foram empregados para estudar vários sistemas diatômicos contendo metais de transição. As abordagens de Teoria de Pertur- bação de Segunda Ordem Multiconfiguracional (CASPT2) ou sua versão Multi-State (MS-CASPT2), baseadas em funções de onda do tipo Complete-Active-Space Self- Consistent-Field (CASSCF) foram utilizadas, com o conjunto base do tipo Orbitais Naturais contraídas em ambiente relativístico (ANO - RCC) com qualidade quádrupla- , para se estudar esses sistemas. Em relação aos dímeros de metais de transição homonucleares (Re2, Tc2, Ta2, Mo2 e W2), caracterizamos seu estado fundamental e diversos estados excitados através das curvas de energia potencial, constantes espectroscópicas e ordens de ligação efetiva. Todos os dímeros estudados por nós apresentam multiplicidades de ligação acima de quatro. Para esses sistemas também estudamos os efeitos do desdobramento causado pelo acoplamento spin-órbita com o intuito de determinar inequivocadamente a simetria do estado fundamental e, também, de auxiliar na interpretação dos espectros experimentais, quando existentes. Sobre as diatômicas formadas pela junção de um átomo de metal de transição e um elemento do grupo principal, enfocamos principalmente os nitretos e os boretos de metais de transição (CoN, MnN, TcN e RhB). Da mesma maneira, os sistemas foram descritos em termos de suas curvas de energia potencial e constantes espectroscópicas e foram comparadas com outros resultados teóricos e experimentais. Todas as moléculas estudadas nessa parte são caracterizadas por ligações triplas, com um par de elétrons sobre o átomo não metálico e os elétrons restantes localizados sobre o metal, acoplados de diferentes formas / In this work, high level ab initio multiconfigurational methods with extensive basis set and inclusion of relativistic e¤ects were employed to study several diatomic systems containing transition metals. The Multiconfiguration Second Order Perturbation Theory (CASPT2) or its Multi-State version (MS-CASPT2) approaches, based on Complete- Active-Space Self-Consistent-Field (CASSCF), were employed, with the Atomic Natural Orbital contracted in a relativistic environment (ANO-RCC) with quadruple- quality, in order to study these systems. In relation to the homonuclear dimers of transition metals atoms (Re2, Tc2, Ta2, Mo2, and W2), we have characterized their ground state and several excited states through potential energy curves, spectroscopic constants and e¤ective bond orders. All dimers we studied have the multiplicity of the chemical bond above four. To these kind of systems, we have also studied the splitting caused by spin-orbit coupling with the the aim of determine the symmetry of the ground state and help in the interpretation of the experimental spectras. About the diatomic formed by joining of a transition metal atom and an atom of the main group, we have focused, mainly, the transition metal nitrites and borides (CoN, MnN, TcN, and RhB) In the same way, these systems were described in terms of their potential energy curves, spectroscopic constants and wavefunctions and we have com- pared to other theoretical and experimental results. All molecules studied in this part were characterized as triple bonded, with a pair of electrons on the non–metalic center and the remaining electrons localized on the metal, coupled on di¤erent forms

京都大学 / 新制・課程博士 / 博士(工学) / 甲第23160号 / 工博第4804号 / 新制||工||1751(附属図書館) / 京都大学大学院工学研究科分子工学専攻 / (主査)教授 関 修平, 教授 今堀 博, 教授 梶 弘典 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

About 85% of the world’s energy is derived from non-renewable sources—coal, petroleum, and natural gas. Solar photocatalysis is one way to potentially generate cheap renewable fuels by harnessing energy from the sun using a photosensitizer and converting it into chemical energy. The efficiency of a photosensitizer depends on its capacity to form a prolonged triplet excited state. Zinc dipyrrin complexes have the potential to be efficient sensitizers for reductive photochemistry, but their ability to form long-lived triplet excited states still needs extensive research. The overall aim of this research is to probe the role charge separation plays in the formation of triplet state in metal complexes of dipyrrin photosensitizers. The specific objectives are to synthesize and characterize zinc and boron dipyrrin complexes, analyze their photophysical properties—such as steady state spectroscopy, low temperature emission spectroscopy—and quantify their triplet states using time-resolved transient absorption spectroscopy.

The threshold potentials were determined for the excitation energy necessary for low energy electrons to induce chemical reactions of carbon monoxide, and of nitric oxide adsorbed on a gold surface. The reactions were studied as a function of temperature (100 °C to 200 °C) and pressure (1.83 x 10-5 to 6.40 x 10-4 torr). The electron source was a thorium oxide coated iridium filament which was heated by a current between 1A and 3A to keep thermal distribution of the electrons to less than 0.4 ev. The reaction surface was a polycrystalline evaporated film prepared by subliming gold onto a stainless steel mesh support. Mass analysis was done by quadrupole mass spectrometry in a flow system. The general results of the research is that a technique has been developed to study the products of reactions of excited state atoms or molecules on metal surfaces. The electron-impact excitation method is an alternative to photochemical and other methods.

In this work, a study of a recent approach in the design of light-driven molecular motors is presented. The approach involves enabling part of the motor to obtain aromatic-like properties through photoexcitation, and is found to significantly facilitate the rotary motion by reducing the barriers normally present in the excited-state potential energy surfaces of rotary motors.

Very short lifetimes of excited states of isolated bases in nucleic acids, on the picosec- ond order, are believed to contribute to photostability of the genetic code. When embedded in DNA this behavior becomes more complex, mainly due to their inter- actions via stacking and hydrogen bonding. The DNA photophysiscs is not fully understood yet. It depends e.g. on the conformation and the character of excited states. The studies on smaller systems can help to improve the understanding of these phenomena. The aim of this work was to examine the dynamics of the excited states of the n → π∗ character of the complex of N-methylformamide dimer and two waters. The study was performed using non-adiabatic dynamics simulations with on-the-fly Surface Hopping algorithm based on the potential energy surfaces and non-adiabatic couplings obtained with multi-reference approach. The results show that after the vertical excitation into delocalized S2 state the system relaxes into S1 state within several tens femtoseconds. For majority of the population, the charac- ter of the state then oscillates between localized and delocalized during the whole course of the dynamics. Comparison with calculations with the waters removed in- dicates that the delocalization is caused by waters serving as a bridge between the two chromophores. 1

We propose a new method of calculating electronically excited states that combines a density functional theory based ground state calculation with a linear response treatment that employs approximations used in the time-dependent density functional based tight binding (TD-DFTB) approach. The new method termed time-dependent density functional theory TD-DFT+TB does not rely on the DFTB parametrization and is therefore applicable to systems involving all combinations of elements. We show that the new method yields UV/Vis absorption spectra that are in excellent agreement with computationally much more expensive TD-DFT calculations. Errors in vertical excitation energies are reduced by a factor of two compared to TD-DFTB.

京都大学 / 新制・課程博士 / 博士(理学) / 甲第24412号 / 理博第4911号 / 新制||理||1702(附属図書館) / 京都大学大学院理学研究科物理学・宇宙物理学専攻 / (主査)教授 橋本 幸士, 准教授 福間 將文, 教授 杉本 茂樹 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DFAM

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Covalent SP3-hybridization defects in single-walled carbon nanotubes (CNTs) have been prevalent in recent experimental and theoretical studies for their interesting photophysical properties. These systems are able to act as excellent sources of single, infrared photons, even at room temperature, making them marketable for applications to sensing, telecommunications, and quantum information. This work was motivated by recent experimental studies on controllable defect placement and concentration as well as investigating carrier multiplication (CM) using DFT-based many-body perturbation theory (MBPT) methods to describe excitonic relaxation processes. We find that pristine CNTs do not yield appreciable MEG at the minimum threshold of twice the optical gap 2Eg, but covalent functionalization allows for improved MEG at the threshold. Finally, we see that defect-defect interactions within CNT systems can be modeled simply as HJ-aggregates in an effective Hamiltonian model, which is shown to be valid for certain, highly-redshifted defect configurations at low defect-defect separation lengths.