Absorption and fluorescence of OClO (A)over-tilde 2A2-(X)over-tilde 2B1 in solid Ne, Ar, and Kr.: I.: Vibrationally unrelaxed (A)over-tilde→(X)over-tilde emission

Dispersed laser-induced fluorescence of the (A) over tilde (2)A(2)-->(X) over tilde B-2(1) transition of OClO in solid Ne in the spectral range 500-770 nm was recorded when the origin at 20 991 cm(-1) was excited. Progressions with spacings near 939 and 446 cm(-1) are associated with vibrational modes nu(1) and nu(2) of the (X) over tilde state. A simultaneous fit of bath modes yields omega(1)" = 957.1+/-1.4, omega(2)" = 452.6+/-0.4, x(11)" = 4.47+/-0.04, x(22)" = 0.54+/-0.05, and x(12)" = 4.00+/-0.05 cm(-1). When the 1(0)(1) line of the (A) over tilde-(X) over tilde system at 21 699 cm(-1) was excited, vibrationally unrelaxed emission was observed in the spectral region 480-600 nm. Excitation of the 2(0)(1) line at 21 284 cm(-1) generated weak vibrationally unrelaxed progressions. The visible absorption spectrum of OClO in solid Ne in the region 415-488 nm was recorded with a Fourier-transform spectrometer, yielding nu(00) = 20 991.3, nu(1)' = 707.9, nu(2)' = 292.5, and 2 nu(3)' = 887.6 cm(-1) for the (A) over tilde state. Simultaneous fits considering either only nu(1) and nu(2) modes or all three modes yield corresponding spectral parameters. Similar experiments were performed with OClO in solid Ar and Kr. Pronounced increases in nu(1)' (716.0 cm(-1) in Ar and 712.5 cm(-1) in Kr) and nu(2)' (302.3 cm(-1) in Ar and 303.0 cm(-1) in Kr) and a decrease in nu(00) (188 cm(-1) and 331 cm(-1) red-shifted, respectively) from that in the gas phase indicate substantial perturbation of the A state in solid Ar and Kr. An absorption continuum underlying the A-X system is attributed to absorption to the (1) over tilde(2)A(1) State above the predissociation barrier. The phonon interaction increases and the threshold of the continuum decreases as the matrix host is altered from Ne to Ar to Kr. (C) 1998 American Institute of Physics.