Raman Spectra of the Products of Na and K Atom Argon Matrix Reactions with O2 Molecules

Abstract

Raman spectra of samples of sodium and potassium atoms codeposited at 16°K with oxygen molecules at high dilution in argon showed strong bands at 1094 and 1108 cm−1, respectively, which are assigned to the superoxide fundamentals in the Na+O2− and K+O2− molecules. These features were split into triplets using 16O2, 16O18O, 18O2 samples, which indicates isosceles triangular structures; absence of M+–O2− interionic modes confirms the ionic model for the alkali superoxide molecules. Infrared bands at 1079 and 1097–1104 cm−1 in Na and K atom −O2 reactions, respectively, are assigned to the dimeric species (M+O2−)2. The symmetric metal-oxygen mode for O2KO2 was observed in the Raman at 305 cm−1, inferring more covalent character in the metal oxygen bonding in this species than in the alkali superoxides.