In this paper we show the existence of circular dichroism in both integrated as well as differential Auger currents produced in the decay of a vacancy created by the absorption of a circularly polarized photon in a gaseous linear molecule. It arises due to a rotational orientation of the photoexcited molecule or excited photoion. Although Auger electrons in such experiments should necessarily be observed along with their spins, neither the spin-orbit nor spin-rotation interactions, however, need to be taken into account. Circumstances when dichroic effects in such experiments are independent of photoabsorption and/or Auger-emission dynamics have also been clearly brought out by us. We have calculated the magnitude of the circular dichroism for certain realistic cases and have shown it to be of the order of magnitude of the total Auger intensity. It is proposed that circular dichroism in Auger spectroscopy provides a direct and simple method to probe rotational orientation produced by the absorption of circularly polarized light in gaseous linear molecules and to calibrate the degree of circular polarization of electromagnetic radiations over a wide range of photon energy.

• Received 1 February 1993

DOI:https://doi.org/10.1103/PhysRevA.48.2084