Knowledge Bank

Atmospheric remote sounding requires an increasingly accurate knowledge of the spectral properties of gases under environmental conditions. To that end, high-resolution measurements of the broadening and shifting of several $CO-N2$ fundamental P and R branch lines are presented at $-45\circ C$ and $-10\circ C$, and pressures of about 50 kPa. Combining our broadening results with previously published $dataa$, the measured temperature dependence of the broadening coefficients is compared with the temperature dependence predicted by the usual scaling law, $\gamma 2/\gamma 1=(T1/T2)-n$. It is shown that the law is no longer accurate within experimental error. The temperature dependence of the shifts is also measured.