EVIDENCE FOR LIGHT-INDUCED KINETIC EFFECTS DUE TO VELOCITY-SELECTIVE HEATING OR COOLING

If velocity-selective optical excitation in a gas is followed by rapid collisional deexcitation, the result may be called velocity-selective heating. Through the temperature dependence of the transport coefficients, this process gives rise to a new type of kinetic effect. This is experimentally demonstrated using hot-band rovibrational excitation of CO2 gas by a CO2 laser tuned in the Doppler wing. Upon R- or P-branch excitation, rotational- to kinetic-energy conversion yields velocity-selective heating or cooling. This results in a light-induced flow for nonuniform illumination. © 1990 The American Physical Society.