Enhanced laser cooling of CO2-Xe gas using (0200) excitation

Laser irradiation with a 9.6 μm wavelength resonant with the (02⁰0) level improves the anti-Stokes cooling of CO2 gas. Excitation of the (02⁰0) level increases cooling by producing a larger population of (00⁰1), despite the higher-energy photon absorption, compared to a (10⁰0) level excitation. Further selection of macroconditions (temperature, pressure, Xe diluent atomic fraction, and geometric parameters) enhances cooling by reducing parasite gas conduction through slower thermal energy transport and increasing the nonequilibrium population of the excited (00⁰1) level by fast species diffusion and small collisional relaxation. We include reabsorption, and then find the conditions for optimal cooling.