Polarization and intensity spectra for Mg-Ne and Mg-Ar fractional collisions.

Abstract

Extensive experimental studies of Mg-Ne and Mg-Ar fractional collisions are reported. In the fractional-collision process, two-color, two-photon absorption takes place during a single binary collision. Polarization and relative intensity spectra were measured in an approximately \ifmmode\pm\else\textpm\fi{}50-${\mathrm{cm}}^{\mathrm{\ensuremath{-}}1}$ range around the atomic Mg 3s $^{1}$${\mathit{S}}_{0}$\ensuremath{\rightarrow}3p $^{1}$${\mathit{P}}_{1}$\ensuremath{\rightarrow}5s $^{1}$${\mathit{S}}_{0}$ two-photon resonance. The generally-weak-field spectra show a remarkable phenomenology associated with the relative linear-polarization directions of the two exciting laser beams and with their separate detunings from atomic one-photon resonance. The polarization and relative absorption spectra display effects due to relative detuning, multiple Condon points, and laser intensity. Details of our experimental approach, and spectra for the process in Mg-Ar and Mg-Ne are presented and discussed. The data are seen to contain information on the short-range collision dynamics of the Mg--rare-gas pairs, and on the development of the alignment over the course of the collision.