Time-Resolved and Frequency-Resolved Laser Spectroscopy in Free and Perturbed Atoms

Abstract: Time-resolved VUV laser spectroscopy has been performed to determine radiative lifetimes of several elements in atomic-beam systems. VUV radiation was generated by means of resonant four-wave mixing and stimulated anti-Stokes Raman shifting. Several methods to produce free atoms are presented and different techniques to determine radiative lifetimes are discussed. Doppler-free laser spectroscopy is discussed for optically thin samples. High-contrast laser spectroscopy was introduced for optically thick samples. Results from a single sodium cell and two cells in tandem are presented. Subnatural linewidths down to 50% of the natural linewidths were obtained in a special experimental arrangement. The temporal behaviour of high-contrast laser spectroscopy has also been studied. Some unexpected results were observed. The density matrix equation was used to explain the experimental results. Energy transfer processes due to inelastic collisions were studied at even higher densities using CW lasers. Several precautions are discussed in detail in order to obtain accurate energy transfer cross sections. Energy transfer cross sections for several processes were derived.