Knowledge Bank

The continuous microwave excited emission spectrum of argon in the region 1050 to $1400\backslash AA$ has been studied as function of discharge pressure. The intensity in the region below $1100\backslash AA$ is reduced by self-absorption of $Ar2$ van der Waals molecules especially at the higher pressures. The atmospheric absorption coefficients $(\alpha =1/l\log I0/I)$ of both argon and krypton near their resonance lines $(1066\backslash AAand1235\backslash AA)$ are shown to be a linear function of pressure, in support of the existence of slightly attractive potential curves for rare gas molecules in their ground states. The absorption line profiles of the krypton resonance lines at $1235\backslash AA(1So\to 3P1)$ and $1164\backslash AA(1Soto1P1)$ have been studied in some detail, yielding absorption coefficients and oscillator strengths for these lines.