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

Document Type

Article

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.