THE INFRARED AND NEAR-INFRARED SPECTRA OF HCC AND DCC TRAPPED IN SOLID NEON

Spectra have been recorded from 700 to 12 000 cm(-1) for HCC and DCC trapped in solid neon. In this region, which includes not only the groundstate absorptions but also all of the absorptions of appreciable intensity in the highly perturbed A (II)-I-2 state, all of the matrix shifts are to lower frequencies, and none of them exceeds 30 cm(-1). The ($) over tilde X(OnO) and ($) over tilde X(Onl) progressions of HCC, recently reported in the photoelectron spectrum of HCC-, also appear in the infrared spectrum. The spectra of the singly and doubly carbon-13 substituted species of HCC and of doubly carbon-13 substituted DCC are presented. Except in a few regions of very strong mixing of energy levels of the ($) over tilde X and ($) over tilde A states, correlations of the HCC and DCC bands with their carbon-13 substitution counterparts are possible, and the resulting isotopic shift data are useful in assigning the vibronic spectra. Assignments are proposed for a considerable number of HCC and DCC bands. These assignments are aided by the carbon-13 shift data, by the results of recent ab initio calculations. and, where they are available, by the upper-state symmetries of bands observed in the gas phase. Absorptions of C-2, C-2(-), C-4, HC4, HCCO, and C2H3 isolated in a neon matrix are also identified. (C) 1995 Academic Press, Inc.