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

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 ${\mathrm{Na}}^{+}{\mathrm{O}}_2^{-}$ and ${\mathrm{K}}^{+}{\mathrm{O}}_2^{-}$ molecules. These features were split into triplets using ¹⁶O₂, ¹⁶O¹⁸O, ¹⁸O₂ samples, which indicates isosceles triangular structures; absence of ${\mathrm{M}}^{+}–{\mathrm{O}}_2^{-}$ 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 ${\mathrm{-O}}_2\hspace{0.17em}\mathrm{reactions}$ , respectively, are assigned to the dimeric species $({\mathrm{M}}^{+}{\mathrm{O}}_2^{-}{)}_2$ . 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.