Infrared Spectrum and Structure of Intermediates in the Reaction of OH with CO

Abstract

Upon vacuum-ultraviolet photolysis of H2O in a CO matrix at 14°K, infrared absorptions of HCO, H2CO, HCOOH, and CO2 become prominent. Furthermore, new absorptions due to reactive product species appear at 615, 620, 1077, 1088, 1160, 1261, 1797, 1833, 3316, and 3456 cm−1. These absorptions diminish in intensity when the sample is subjected to radiation in the 2000–3000-Å spectral range. Detailed consideration of the processes which may occur in this system and extensive isotopic substitution studies support the assignment of these absorptions to the cis and trans stereoisomers of H–O–C=O, produced by the reaction of OH with the CO matrix. Valence force potentials having only small contributions from interaction terms have been found which correspond to a physically reasonable vibrational assignment and which satisfactorily reproduce the pattern of observed frequencies for the various isotopic species of both cis- and trans-HOCO. Evidence suggests that cis- and trans-HOCO photodecompose to produce H atoms and CO2.