Photon Echo Polarization Measurements in SF₆ and SiF₄

Abstract

The photon echo technique has become a valuable experimental tool for studying molecular processes. The polarization of the photon echo was first studied theoretically and experimentally by Abella et al. [1]. They studied the photon echo stimulated in ruby by exciting pulses from a ruby laser. Gordon et al. [2] studied the polarization of the photon echo stimulated in gaseous SF₆ by the P(20) laser line of CO₂. They used their experimental results and theoretical arguments to make inferences about the total angular momentum or the J-values of the levels which were involved in the absorption of the radiation. They did not observe a component of the echo polarization perpendicular to the polarization of the second pulse. Some of their conclusions were in error. Alimpiev and Karlov [3] studied the echo polarization with a linear-linear excitation sequence, and with excitation by P(16) were able to observe a small echo polarization component perpendicular to the second pulse polarization. Although their theoretical development was applicable only to states with small J-values, they concluded that P(16) radiation was absorbed by a Q-branch transition in SF₆. They did not observe the perpendicular component with P(18) and P(20) excitation.