Study of coherence in electron-impact excitation of mercury

Ali Zaidi, Ian A. McGregor, Hans Kleinpoppen

The electron-photon delayed-coincidence technique was used to measure the coincident photon radiation for the $6^{1}S_{0}\ensuremath{\rightarrow}6^{3}P_{1}\ensuremath{\rightarrow}6^{1}S_{0}$ process of mercury by electron impact. This process, which is found to be partially coherent, has been analyzed with a new parametrization which takes into account spin-orbit coupling.

E.G. Aleksandrov

D. Fogel, Yu. A. Tolmachev

T. Hadeishi

Detailed information is given on an experiment which we have reported previously, studying intensity beats in the resonance absorption due to nondegenerate magnetic sublevels of the $^{3}P_{2}$ mercury metastable state coherently excited by electron impact. Rather straightforward theory is used to explain the experimental result. It is found that regardless of the exciting energy, as long as there is sufficient selective excitation of certain magnetic sublevels, the absorption beat frequency is modulated at twice the Larmor frequency when the incident electron beam is perpendicular to the externally applied field ${H}_{0}$ and the linearly polarized monitoring light is perpendicular to the electron beam.

Ali Zaidi, Ian A. McGregor, Hans Kleinpoppen

An isotope cell was used to eliminate the effect of hyperfine structure on the polarisation of radiation, near threshold, for the 6 3 P 1 -6 1 S 0 line of mercury (253.7 nm) excited by electron impact. These results are compared with the polarisation of the radiation when hyperfine structure is present.