Observation of paramagnetic Raman optical activity of nitrogen dioxide

Abstract

Raman optical activity (ROA) detects the intensity difference between right and left circularly polarized scattered light, and thus brings about enhanced information about the molecules under investigation. The difference is quite small and the technique is mostly constrained to the condensed phase. For NO 2 in the presence of a static magnetic field, however, the ROA signal with high ROA/Raman intensity ratio was observed. The signal is so strong owing to molecular paramagnetism and a pre-resonance signal enhancement. The spectral shape was explained on the basis of the Fermi golden rule and rotational wave functions expanded to a spherical top basis. The results indicate that the technique can be immediately used to obtain information about molecular properties, such as polarizability components. It also has a potential to detect other paramagnetic gases and discriminate among them. Paramagnetic gases: Paramagnetic Raman optical activity of nitrogen dioxide was observed for the first time and explained on the basis of angular momentum theory (see picture). The technique provides enhanced information about molecular properties, and the results suggest that the technique can be immediately used for discrimination and analysis of similar paramagnetic gases. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.