TheKX-Ray Absorption Structure ofCl2and HCl

The fine structure on the short wavelength side of the $K$ x-ray absorption edge of chlorine in ${\mathrm{Cl}}_2$ and in HCl has been measured with a vacuum double crystal spectrometer using Geiger counter registration. Pronounced structure was obtained which agreed well with structure previously detected using lower resolution and photographic registration. However, the structure does not agree with the theory. Some reasons for the discrepancy in terms of the optical levels and the different types of binding in the two cases are discussed.