Laser-Induced Continuum Structure and Third Harmonic Generation in - and Two-Valence Atoms.

A model for calculating third harmonic generation (THG) in a near-resonantly coupled 4-level atomic system in the presence of laser-induced continuum structure (LICS) is formulated in terms of the time dependent density matrix elements which can be obtained by solving the time dependent density matrix equations for the atomic system interacting with laser pulses. The theory is applied to a single-valence -electron atom, sodium, as well as to a two-valence-electron atom, calcium. Analysis of the existing experimental data in sodium is given applying our theoretical model. It is found that the spatio-temporal overlap of the two laser pulses is a very sensitive factor for the experimental observation. Calculations of atomic parameters for a two -valence-electron atom (calcium) using multiconfiguration Hartree-Fock method with finite B spline basis is also presented. (Copies available exclusively from Micrographics Department, Doheny Library, USC, Los Angeles, CA 90089 -0182.).