REACTIONS OF LASER-ABLATED CHROMIUM ATOMS WITH DIOXYGEN - INFRARED-SPECTRA OF CRO, OCRO, CROO, CRO3, CR(OO)(2), CR2O2, CR2O3 AND CR2O4 IN SOLID ARGON

Reactions of laser-ablated Cr atoms with O-2 gave a very strong, sharp 965.4 cm(-1) band and weak, sharp 1869.7, 984.3, 914.4, 846.3, 716.2, and 643.1 cm(-1) bands. The 1869.7, 965.4, and 914.4 cm(-1) bands tra ck together on annealing, show Cr-52, Cr-53, Cr-54 isotopic splittings appropriate for a single Cr atom and triplets with statistical O-16,1 8(2) for two equivalent O atoms, and are assigned to the upsilon(1) upsilon(3), upsilon(3) and upsilon(1) modes of the bent (128 degrees+/ -4 degrees) chromium dioxide OCrO molecule. The 984.3 cm(-1) band show s chromium isotopic splittings for two Cr atoms and O-16,18(2) compone nts for two O atoms, and is attributed to the bent CrOCrO molecule. Th e weak 846.3 cm(-1) band exhibits proper oxygen isotopic behavior for CrO and is redshifted 39 cm(-1) from the gas-phase value, the maximum shift observed for a first row transition metal monoxide. The sharp 71 6.2 and 643.1 cm(-1) bands crack together; the former reveals Cr isoto pic splittings for two Cr atoms and the latter O-16,18(2) splittings f or two sets of dioxygen subunits; the branched-puckered-ring dimer O(C r2O2)O is identified. Annealing produces new bands due to CrOO, CrO3, Cr(OO)(2) and the ring dimers (Cr2O2) and (Cr2O2)O, which are identifi ed from isotopic shifts and splitting patterns. (C) 1997 American Inst itute of Physics.