Analytical solutions for infrared-laser-driven diffusion in polyatomic gas mixtures

We use an effective bimodal velocity distribution in a five-level model to analytically examine the problem of laser-driven gas transport in mixtures of an absorbing gas and a buffer gas. Analytic expressions expressions are given for the steady-state active-gas density distribution in a closed tube for a uniform excitation profile. The model also predicts that laser-induced transport may occur without a buffer gas if collisions favoring simultaneous vibrational deactivation and velocity change occur. Profiles are given for C${\mathrm{H}}_3$F:He mixtures when a C${\mathrm{O}}_2$ laser is used to excite the $Q_{12,2}$, ${\nu }_3$ band absorption.