VUV dissociative excitation cross sections of H2O, NH3, and CH4 by electron impact

Absolute excitation functions for excited fragments resulting from electron bombardment of H2O, NH3, and CH4 by low energy electrons (0–300 eV) have been measured in the VUV (1100–1950 Å). The predominant emission for each molecule was the H Lyman-α line while the OI, NI, CI, and CII emissions were at least an order of magnitude weaker. Absolute cross sections at 100 eV are given along with the appearance potential of the various processes and the possible dissociative-excitation channels through which such processes proceed.