IR, UV and visible absorption of X irradiated single crystals of sodium nitrite

X irradiation of NaNO2 single crystals, induces a motion of some NO2- ions, mainly around the axis perpendicular to their planes (a axis). The change in the orientation of NO2- is observed on the ν2 vibration of NO2- (by IR absorption) and on the vibronic structures associated with the NO2- electronic transitions (by UV and visible absorption). Other centers, like NO3-, are also produced by irradiation. Their evolution with temperature is studied. (author)