Photofragmentation spectroscopy of the zirconium and niobium cluster cations and ab initio studies.

摘要

This thesis describes research done in the field of cluster chemistry. It is virtually divided into three parts. Virtual part I describes experimental studies of metal cluster cations in gas phase, and virtual part II describes the ab initio methods; experimental and theoretical results are presented in virtual part III.; A metal cluster is a group of metal atoms consisting of two to several thousand metal atoms in gas, liquid, solid, and plasma phase. Chemical physicists studying the spectra of transition metal clusters produced in supersonic nozzle beams and detected by either resonant two-photon ionization or photofragmentation allude in their discussions to the metal-metal multiple bonding. In the field of cluster chemistry and physics the aim is to understand how a chemical process depends on cluster size, how the chemistry of a metal changes with its state of aggregation, and how structural, electronic, optical, and magnetic properties vary with cluster size, eventually reaching those of the bulk metal. Even for small transition metal (ionic) clusters, their electronic structures are complexes and remain questions. For theory, too, the future holds its challenges. Even cluster as small as diatomics may prove difficult species to get right answers for because of the partially occupied d orbitals. Therefore, it is difficult to calculate the exchange-correlation energy contribution to the system in an accurate manner.; Virtual part I consists of three chapter. Chapter I is an introduction, Chapter II and III describe the instrument and experimental conditions, respectively. Virtual part II consists of two chapters. In Chapter IV, the theoretical methods are discussed. In Chapter V, spin-orbit interaction is discussed. Virtual part III covers chapters VI to XI. Chapter VI shows the experimental and theoretical results for Zr2+. In chapters VII to IX, the experimental and theoretical result for Nb2+, Nb3 +, and Nb4+ are given. In Chapter X, the electronic spectra of the Nb2+ and possible assignments are given. Chapter XI is the conclusion.