Infrared Spectrum of the NO2− Ion Isolated in an Argon Matrix

The molecular ion NO2− has been stabilized in an argon matrix in sufficient concentration for detection of its antisymmetric stretching fundamental, ν3, at 1244 cm−1 by electron bombardment or photoionization of matrix-isolated NO2 and by the interaction of an alkali-metal atomic beam with NO2 in an argon matrix. In contrast to the position of this fundamental in an inert, nonionic environment, a value of approximately 1275 cm−1 is characteristic of the crystalline material. Isotopic data are consistent with a 115° valence angle for NO2−, independent of environment. Irradiation of the sample with light of wavelength near 3150 Å leads to the destruction of the NO2− absorption in the studies of the electron bombardment and photoionization of NO2, but not in the experiments in which the alkali metal atoms provide a reservoir of photoelectrons.