Absorption Coefficients of Xenon and Argon in the 600–1025 Å Wavelength Regions

Absorption coefficients of xenon and argon have been measured at wavelengths between the ${}^2{P}_{\frac{3}{2}}$ ionization threshold (Xe, 1023 Å; Ar, 787 Å) and 600 Å. Similar measurements have recently been reported by us for krypton [Appl. Opt., September 1963]. A photoelectric scanning technique with a Hopfield helium continuum source as background was used at a bandwidth of 0.5 Å. The oscillator strengths of the auto‐ionized lines which belong to the two overlapping series p⁶(¹S₀) —p⁵(²P_½)ns′ and p⁶(¹S₀) —p⁵(²P_½)nd′ and which occur between the ${}^2{P}_{\frac{3}{2}}$ and ²P_½ ionization limits were calculated from the measured absorption coefficient curve. The total oscillator strength was 0.60±25% for the first six Xe peaks and 0.011±25% for the first four Ar peaks. For xenon, the k value is 2100 cm^—1±10% at the ²P_½ threshold, and it drops smoothly to 1050 cm^—1 at 600 Å. For argon, the k value is 930±10% at the ²P_½ threshold, and the curve rises smoothly to 1200 cm^—1 at 600 Å. In both cases, no lines or thresholds were observed at wavelengths shorter than the ²P_½ threshold. Comparison is made with ionization efficiency data.