Relative Experimental Cross Sections for Excitation ofIons by Electron Impact (8.0-98 eV)
- 5 February 1969
- journal article
- research article
- Published by American Physical Society (APS) in Physical Review B
- Vol. 178 (1), 182-197
- https://doi.org/10.1103/physrev.178.182
Abstract
A crossed beam technique has been developed for measuring the emission cross section for the excitation of electric dipole transitions in ions by electron impact. The experimental method involves crossing modulated ion and electron beams in a well-defined collision volume. A portion of the photon flux radiated from the excited ions is detected at an angle of 90° to the plane of the two beams by direct observation of the collision volume with a photomultiplier tube. The selection of a single emission line is accomplished with an interference filter. The total flux of radiation from the collision volume for a particular transition can be determined with a knowledge of the photon detection probability of the apparatus. The possibility of an anisotropic angular distribution of radiation from the collision volume is evaluated by measuring the polarization fraction. The emission cross section can be determined from the ion and electron beam currents, current density distributions and energies, and the total radiation flux.Keywords
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