ESR investigations of H2O+, HDO+, D2O+, and H2 17O+ isolated in neon matrices at 4 K

Abstract
The H2 16O+, HD 16O+, D2 16O+, and H2 17O+ ion radicals have been generated by photoionization, trapped in neon matrices at 4 K, and investigated by ESR (electron spin resonance) spectroscopy. The magnetic parameters are giso=2.0093(3), Aiso(H)=73.7(6) MHz, and Aiso(17O)=83.5(6) MHz. A weak electronic absorption feature at 6036(3) Å was observed which is tentatively assigned to a known gas phase band. The H2O+ radical appears to be rotating in neon and exhibits an unusual intensity increase as the matrix temperature is lowered from 9 to 4 K. Comparisons between H2O+ and the isoelectronic radicals NH2, NH+3, and CH3 are made.