On the intermolecularity or intramolecularity of nitrosonium nitrate formation in thin films of nitrogen dioxide: A Fourier transform infrared study

The question of whether the formation of the NO+NO−3 (nitrosonium nitrate), the ionic form of nitrogen dioxide, via the decomposition of the ON–O–NO2, ‘‘D′’’ isomer, is an inter- or intramolecular process, is addressed via temperature and concentration dependent FTIR studies of mixed films of N2O4 with CCl4. The process of nitrosonium nitrate production, both during deposition of disordered solid films of nitrogen dioxide and during their subsequent warming, is concluded to be intermolecular but not order dependent. A mechanism is tentatively suggested.