The infrared matrix isolation spectra of carbon dioxide. I. Deuterium matrices : Identification of bands due to carbon dioxide dimers

Abstract

The infrared spectra of CO₂ isolated in deuterium matrices at c.6K are reported for molar ratios of D₂/CO₂ between 50 and 3200. The bending mode V₂ of CO₂ appears as a narrow doublet in the matrix spectra. Bands due to CO₂ dimers are identified in the V₂ region from their concentration dependence and from mixed isotope spectra (¹²CO₂and ¹³CO₂). No dimer bands were observed in the monomer antisymmetric stretching region. In this respect the spectra of CO₂ in D₂ matrices resemble those in N₂ matrices. The observed dimer spectrum is compared with those predicted on the basis of T-shaped and staggered parallel configurations for the dimer and is interpreted as favouring the latter configuration. The desirability of obtaining matrix spectra at sufficiently high resolution is stressed.