Abstract

The function for the excitation of the helium 3¹P level by electron impact has been determined optically. Light intensity of the 3¹P→2¹S transition (5016 A) was detected by a sensitive photomultiplier; its output was measured by a microammeter.

The intensity of the 5016 A line was proportional to electron beam current for all currents used and proportional to helium pressure for less than 3×10⁻⁴ mm. Above 3×10⁻⁴ mm pressure imprisonment of resonance radiation enhanced the light intensity.

The excitation function has a peak value of 2.4×10⁻¹⁸ cm²; this occurs at an electron energy of 100 ev. Absolute determination of the cross section was possible through the calibration of the light detection system by a tungsten ribbon standard lamp. The experimental curve is corrected by removing cascade components from it.

© 1960 Optical Society of America

Helium Level Populations in a Glow Discharge*

William J. Condell
J. Opt. Soc. Am. 50(6) 610-616 (1960)

Collisional Transfer of Excitation Energy in Helium*

Robert M. St. John and Tsu-Wei Nee
J. Opt. Soc. Am. 55(4) 426-432 (1965)

Excitation of the 4F States of Helium*

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Analysis of the He ii 4686-Å (n = 4 to n = 3) Line Complex Excited in an Atomic-Beam Light Source*

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New Wavelengths for Some Helium (He i) Lines

William C. Martin
J. Opt. Soc. Am. 50(2) 174-176 (1960)