Energy dependence of alignment in foil collision-excited n=3 states of He I

Authors

Timothy J. Gay, University of Nebraska - LincolnFollow
H. G. Berry, Argonne National Laboratory, Argonne, Illinois
R. DeSerio, Argonne National Laboratory, Argonne, Illinois
H. P. Garnir, Argonne National Laboratory, Argonne, Illinois
R. M. Schectman, University of Toledo, Toledo, Ohio
N. Schaffel, University of Toledo, Toledo, Ohio
R. D. Hight, University of Nebraska - Lincoln
D.J. Burns, University of Nebraska - LincolnFollow

Date of this Version

April 1981

Comments

Published in Phys. Rev. A 23, 1745 - 1760 (1981) [Issue 4 – April 1981]. ©1981 The American Physical Society. Used by permission.

Abstract

We have measured the beam-foil collision-induced alignment of the 3p ¹P, 3p ³P, 3d ¹D, and 3d ³D states of He I for He+ beam energies between 30 and 1300 keV. The alignment of all four states is found to vary with beam-current density as well as energy. The number of secondary electrons emitted per incident ion, γ, has also been measured as a function of foil temperature and beam energy between 400 and 1400 keV. The rate of change of both alignment and γ with foil temperature exhibits a general correlation. The energy dependence of alignment may be understood in terms of simple impact-excitation collisions. We also discuss our results in terms of the Kupfer-Winter surface electric-field model. The interaction between atoms emerging from the foil and slow secondary electrons is considered.