Matrix-Isolation Study of the Interaction of Electrons and Alkali Metal Atoms with Various Nitrogen Oxides. Infrared Spectra of the Species NO−, NO2−, and N2O2

The infrared spectra which result when samples of NO2 are codeposited with the various alkali metals in an argon matrix at 4 or at 14°K are consistent with the occurrence of strong charge-transfer interaction. In addition to isolated NO2−, previously identified in this system, ion pairs of general formula Mx+NO2− are stabilized. When NO is substituted for NO2, the infrared spectrum of the initial deposit shows an absorption between 1350 and 1375 cm−1 which can be assigned to the NO− stretching fundamental of Mx+NO− ion pairs, in good agreement with the vibrational spacing recently reported for ground-state NO− in the gas phase. Weak charge-transfer interaction occurs between alkali-metal atoms and N2O in an argon matrix environment. Results of the present experiments can be explained by postulating that the upper, predominantly ionic state of the charge-transfer complex decomposes producing O−, which may diffuse through the matrix. A new absorption which appears at 1205 cm−1 has tentatively been assigned to ν4(b1) of a planar O2N=N− anion. In studies of the interaction of sodium atoms with Ar:NO:N2O mixtures, mercury-arc irradiation of the sample leads to the appearance not only of the N2O2− absorption, but also of absorptions due to isolated NO2− and to Nax+NO2−.