Photoelectron angular distributions and phase interference in alkali atoms
Abstract
In this thesis we report an experimental study of the interference between one- and two-photon ionization processes from the ground state of rubidium atom. This interference is observed by measuring the photoelectron angular distribution under the influence of fundamental and second harmonic laser fields. Externally controlling the relative phase and amplitude between these two laser fields, we obtained interference in the angular distribution patterns. This study represents the first observation of the phase interference in photoionization angular distributions. The photoelectron angular distributions resulting from the single-photon ionization of cesium and rubidium from its ground state to the continuum were measured. This is the first set of measurements of the single photon photoelectron angular distributions at a variety of energies in vicinity of the Cooper minimum from a single initial state of alkali metals. The results show a strong variation of asymmetry parameter $\beta$ from its nonrelativistic value of 2. Spin-orbit coupling displaces the minimum in the cross section for excitation to the $\rm \varepsilon P\sb{1/2}$ and $\rm \varepsilon P\sb{3/2}$ and results in a rapid variation of the angular distribution with photon energy in this region. Through the measurement of two-photon ionization angular distributions the quantum defects and spin-orbit coupling were investigated. These studies help us to understand the phase interference interaction, and the data in those studies would be used to analyze the interference processes.
Degree
Ph.D.
Advisors
Elliott, Purdue University.
Subject Area
Electrical engineering
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