Infrared Spectrum of HCO

HCO and DCO have been prepared by the photolysis of HI (DI) and of H2S (D2S) in a CO matrix at 14° and at 20°K. The earlier infrared spectroscopic identification of these species has been confirmed. The C=O stretching frequency of DCO has been revised to 1800 cm—1. Unusually low C–H and C—D stretching frequencies, 2488 and 1937 cm—1, respectively, are obtained. Observations on H13CO and D13CO support these assignments. Spectroscopic, kinetic, and electron spin resonance data all suggest that the C–H bond is exceptionally weak. Fermi resonance may occur between the C—D and C=O stretching modes of DCO. Evidence is presented suggesting that considerable activation energy is required for the reaction of H atoms with CO.