Matrix Isolation Studies: Infrared Spectra of Intermediate Species in the Photolysis of Hydrazoic Acid

Abstract

The matrix isolation method has been used to investigate the photolysis of hydrazoic acid (HN₃) suspended in xenon, argon, and nitrogen matrices at 20°K. Infrared spectra of the photolyzed material in argon and nitrogen matrices show absorption bands of NH₃ and a number of other prominent spectral features that are probably due to unstable molecules, including intermediates in the formation of NH₃. In a xenon matrix no new bands are observed on photolysis of HN₃ at 20°K, but the presence of the imine radical (NH), or of nitrogen and hydrogen atoms, is inferred from the formation of NH₄N₃ when the material is warmed to 70°K. The mechanism of photolytic production of radicals in a matrix is examined, and the probable importance of the heat of fusion of the matrix is discussed. The utility of the matrix isolation technique in the infrared study of unstable reaction intermediates is demonstrated.