Research Papers in Physics and Astronomy


Date of this Version

November 1970


Published by American Physical Society. Phys. Rev. A 2, 1774 (1970). Copyright © 1970 American Physical Society. Permission to use.


The trapped-electron method is applied to the excitation by electron impact of the (2p2)3P state, the lowest doubly excited state of helium which is stable against auto-ionization. The energy of this state, 59.64±0.08 eV, is in good agreement with theory. An estimate of the slope of the total cross section for excitation of the (2p2)3P state at threshold gives a value of 4 × 10-20 cm2/eV.

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