Infrared Detection of the Formyl Radical HCO

Abstract

The photolysis of HI, DI, HBr, and DBr suspended in solid CO at 20°K is described. The formyl radical, HCO or DCO, is produced, as shown by broad absorptions in the visible spectral region (6695, 6352, 6052, 5789, 5548, 5330, 5102 A) which correspond to absorptions of gaseous HCO. Infrared absorptions of HCO (at 1860 and 1091 cm^—1) and of DCO (at 1860 and 856 cm^—1) provide a basis for discussing the chemical bonding of this free radical, and for calculating its thermodynamic properties. These experiments, the first infrared detection of a triatomic free radical by the matrix isolation method, depend upon reactivity of the matrix, possibly eliminating difficulties of the cage effect.