Optoacoustic investigation of the mechanisms in the infrared optogalvanic effect

Simultaneous observations of the optogalvanic and optoacoustic effects were performed in CO₂, NH₃ and SF₆ discharges under irradiation by resonant infrared 10 μm laser radiation. The dependence of the galvanic and acoustic signals on the discharge current, and their time evolution following a switch of the laser radiation were investigated. The observations proved that the infrared optogalvanic effect occurs through two different mechanisms, a gas kinetic temperature dependence of the discharge parameters and a modification of the pion production through the vibrational molecular excitation.