PHOTOABSORPTION AND PHOTOIONIZATION OF CHLORINE DIOXIDE

The high-resolution He I photoelectron spectrum and the absolute vacuum-ultraviolet (vacuum-UV) absorption cross section (6-25 eV) as well as the ionic fragmentation of chlorine dioxide (OClO) are reported. The photoelectron spectrum is interpreted in terms of exchange splitting effects of the various singlet and triplet cation states as well as by comparison to chemically related molecules. The vacuum-UV absorption spectrum shows different Rydberg series converging to the cation states. These Rydberg series and their vibrational progressions are assigned by term value arguments, dipole selection rules, and comparison with the photoelectron spectrum. Photoionization mass spectrometry is used for measurements of the ionization and fragmentation threshold of OClO. The major fragment is ClO+ which occurs above 13.4 eV. Thermochemical data such as heats of formation and bond dissociation energies are derived. No evidence for isomerization of OClO+ is found, as observed for the electronically excited neutral molecule.