Survey of resonant effects in the light emitted by a diatomic molecular gas excited by electronic bombardment

Abstract

It has recently been found that when a molecular gas is excited by electronic bombardment the subsequently emitted light is polarized. In this paper the authors investigate the possibility of studying molecular states excited by this technique in the presence of magnetic and/or electric fields. The measurements are made on the polarization of the light emitted from a level for which the total angular momentum is known. They extend to diatomic molecules the theory of irreducible tensor operators, previously applied to such experiments in atoms. All resonant effects observed in atoms may be expected in molecules, for instance in the presence of the magnetic field the effects of level crossing and magnetic resonance, including their transmission in a cascade decay. When an electric field is added, new effects may arise in polar molecules and make it possible to measure the permanent electric dipole moment and the Lambda doubling in some cases.