The frequency,fluence, and pressure dependence of the absorption of pulsed CO2-laser radiation by SF6 at 140 K

We report measurements of absorption of pulsed CO₂ laser radiation by SF₆ at 140 K. These measurements cover a broad range of fluence (10^?6 to 0.8 J/cm²), SF₆ gas density (2 × 10¹⁵ to 6 × 10¹⁶ cm^?3), and frequency (six CO₂-laser frequencies within the SF₆ v₃ band). We employ two methods of data reduction including one that gives a simple phenomenological function of the three principal independent variables. We conclude that at low fluence a small fraction of the SF₆ molecules absorb the laser radiation and that collisions and higher fluence both increase that fraction. At higher fluence absorption by vibrationally excited molecules becomes increasingly important.