UV laser photodissociation of molecular ions

An apparatus is described for performing molecular ion photofragment spectroscopy with an ultraviolet laser. Preliminary results are given for the photodissociation of H+2 , HD+, D+2 , D2O+, OD+, ND+3 , and ND+2 , using a laser energy of 6.42 eV. Where energetics permit alternative modes of dissociation, selectivity is observed and attributed to selection rules and correlation rules. With polyatomic ions, the distribution of recoil energies provides insight into the partition of excess energy between internal and kinetic energies of products. In the decomposition of ND+3 , results are obtained which call into question some recently reported thermochemical quantities