Experimental andtheoretical study of electron impact excitation of the 3 3P state ofhelium

Abstract

Excitation of the 3 3P state of helium has beenstudied experimentally and theoretically using theconvergent close-coupling (CCC) andR-matrix with pseudo-states (RMPS) methods. The results of apolarization correlation experiment at 40 eV are accurately predicted byboth theoretical methods. The CCC values of the integral polarization alsoagree well with experiment when the influence of cascading states isaccounted for in the calculations. We conclude that the CCC/RMPScalculations provide the most reliable excitation cross sections availableover a wide range of incident electron energies. A comparison is also madebetween experimental and RMPS cross sections and polarizations in theresonance region, 55-60 eV. This model represents the first attempt toexplicitly include physical doubly excited states of neutral helium in aclose-coupling calculation.