Inelastic photon scattering by a polyatomic molecule: NO2

Abstract

When NO2 is illuminated by monochromatic visible light, the frequency distribution of the photonsscattered inelastically consists of discrete spikes superimposed on a broad continuum. This scattered intensity has been compared with the Raman scattering from N2 with respect to the following variables: (i) argon‐ion laser wavelengths; (ii) NO2 pressure; (iii) air pressure. The intensity scattered by a molecule of NO2 is found to be 116 times the Raman intensity from a molecule of N2, NO2 being in air at STP; (the broad continuum intensity from NO2 was measured at 720 cm−1, from the 4880‐Å laser wavelength, with a spectrometer slit width of 10 Å). The quenching constant for the NO2 continuum by air is found to be 67 Torr−1. The observed dependence of the scattered intensity on wavelength and pressure can be explained qualitatively in terms of an expected dense distribution of energy levels in NO2.