Fine structure in dissociative-attachment cross sections for HCl and DCl

Regularly spaced decreasing steps are observed in the Cl - cross section. The spacings correspond, within +or-20 MeV, to the vibrational levels of the HCl and DCl molecules. A schematic cross section convoluted with the measured electron energy distribution is compared with the observed data. The good agreement observed suggests that the theoretical cross section must present sharp decreases. This appears to be a good support for the interpretation previously given by Fiquet-Fayard (1974). An attempt is also made to show that the concept of a resonant state for HCl - is meaningful even for an electronic autodetachment width as large as 1.8 eV.