Study of collisional decay rates of population, orientation, and alignment using stimulated photon echo in SF 6 molecular gas

Abstract

Stimulated photon echo technique with specially chosen linear polarizations of pumping pulses of exciting radiation is applied to investigation of depolarizing collisions in molecular gas SF<SUB>6</SUB> and its mixtures with buffer gases He and Xe. For the first time, the collisional decay rates of population, orientation and alignment of SF<SUB>6</SUB> levels are determined simultaneously. Translational velocity dependence of orientation and alignment collisional decay rates was under investigation. This velocity dependence proved to be negligible within the frames of experimental accuracy both in pure SF<SUB>6</SUB> and in mixtures, which is in agreement with standard theoretical approach accepted for depolarizing collisions. Decay rates of orientation and alignment in pure SF<SUB>6</SUB> have proved lower than velocity changing (elastic) collisions relaxation rate, which allows to conclude, that only some part of elastic collisions participates in destruction of multipole polarization moments of resonant levels. The evidence is obtained for j-dependence of multipole moments relaxation rates SF<SUB>6</SUB>.