Photoionization and excited-state dynamics of molecules with photoelectron imaging spectroscopy

Abstract

The quantum mechanics provides accurate analysis for a wide variety of phenomena in physics and chemistry, such as transitions induced by emission or absorption of a photon. When the molecule absorbs photons, it can not only be photoexcited to another state or photoionized but also dissociated to their photofragments via photodissociation process The photodissociation process reflects molecular dynamics related to energy transfer between the various molecular modes, the breaking of chemical bonds and the creation of new ones, transitions between different electronic states. The detailed study of photodissociation provides intrinsic properties of bonding characters and the nature of an elementary chemical reaction in detailed state-to-state level. Studying the photoionization dynamics also provide important information such as the interaction between the photoelectron and motions of the atomic nuclei in the molecular system. Various photoelectron spectroscopic studies with the optical selection of specific excited state have been used to investigate the excited state specific photoionization/photodissociation dynamics in many molecular systems. To investigate and understand the photoionization or photodissociation dynamics of the molecule, the photoelectron imaging is employed. The photoelectron imaging provides electron kinetic energy and photoelectron angular distribution. The kinetic energies of the photoelectrons provide information on the internal states of the ion formed, which in turn reflect the levels populated in the excited sate. Analysis of photoelectron spectrum with theoretical simulations and propensity rule provides how many changes occur upon photoionization of molecule. The geometrical changes upon ionization can be reflected on change between initial and final ionized state. These allow us to understand the quantum state specific changes in photoionization of molecule. The photoelectron angular distributions are expected to yield useful ...