Infrared spectrum of matrix-isolated nitric acid

The infrared spectra of four isotopic species of matrix−isolated nitric acid have been obtained. The vibrational assignments are in general agreement with previous gas and condensed phase observations with the exception of those assigned to the NO2 valence bend and NO′ single bond stretch. The results of diffusion experiments performed indicate that nitric acid may form cyclic dimers similar to the carboxylic acids.