Some observations on the continuum emission from NO2

Abstract

The fluorescence spectrum of NO2 produced by laser excitation in the visible region consists of a discrete banded structure superimposed on what appears to be a continuum. Previous experiments have implied that the intensity of continuum emission increases relative to that of the discrete emission as the pressure is raised, and that therefore the continuum emission is produced by some collision mechanism. In this paper we describe some magnetic quenching experiments which indicate that the continuum/discrete ratio is pressure independent. We also describe experiments which indicate that the continuum emission lifetime is longer than the discrete emission lifetime, and this allows a reinterpretation of previous observations which is not in conflict with the conclusion based on our magnetic quenching data. These observations suggest that either the continuum emission originates in the isolated molecule, or else, that the cross section for any bimolecular process is extremely large.