Photodissociative channels at 1216 Å for H2O, NH3, and CH4

Abstract

H(2 S) and O(1 D, 3 P) yields have been measured from photolysis of H2O, NH3, and CH4 at 1216 Å. From H2O, it is confirmed that the H2+O(1 D) channel occurs with a yield of 0.1, but in addition there is a yield of 0.12 for the channel giving 2H(2 S)+O(3 P). The remaining process is H+OH production. For NH3, the NH+2H(2 S) channel accounts for at least 90% of the dissociation. For CH4, combination of our data with earlier work on H2 and CH production at 1236 Å leads to the conclusion that the two major dissociative channels generate 1CH2+H2 and CH2+2H(2 S), with comparable probabilities. CH and CH3 production is at most minor. The yields at 1216 Å for the three‐fragment processes O+2H, NH+2H, and CH2+2H, exhibit a dependence on the available excess energy.