Response time of dynamic thermal holograms in 34SF6 in four-wave mixing of CO2-laser pulses

The four-wave mixing of the pulses from an electron-beam-sustained CO₂ laser in sulfur hexafluoride with isotopically substituted sulfur (³⁴SF₆) has been studied experimentally. The frequency of the signal wave was shifted from that of the pump waves. The time constant of the response of the thermal gratings which arise has been found experimentally as a function of the gas pressure and the signal-pump angle. This response time is determined by the VT relaxation time of the ³⁴SF₆, i.e., by the time scale for the thermalization of the energy in the gas.