Photophoresis of a fine particle in a selectively excited gas

Motion in a binary gas mixture of a fine particle affected by resonant optical radiation is considered. The Doppler effect leads to the velocity-selective absorption of the traveling light wave by molecules of one of the gas components. Radiation transfers the absorbing molecules from the ground state to excited ones. As a result, the kinetic cross section and accommodation coefficient of molecules, which have absorbed radiation, change. Maxwellian distribution for the absorbing gas molecules becomes distorted and the aerosol particle begins to be influenced by a force. This photophoretic force and velocity of the photophoresis are calculated by taking both the optical and kinetic characteristics of the gas molecules into account.