Electron scattering from 4He and Ne clusters: determination of the cluster density from the electronic surface barrier potential

✍ Scribed by K. Martini; J.P. Toennies; C. Winkler

• Publisher: Elsevier Science
• Year: 1991
• Tongue: English
• Weight: 563 KB
• Volume: 178
• Category: Article
• ISSN: 0009-2614
• DOI: 10.1016/0009-2614(91)90277-g

✦ Synopsis

A monoenergetic beam of electrons is scattered from a beam of "He clusters. The angular distribution of the scattered electronically excited atoms and clusters is measured by an open Venetian-blind multiplier, which is rotatable in the plane of both beams. The threshold electron energy for excitation of the clusters shows a shift to higher energies with respect to the alom component by between 0.6 and 1.1 eV depending on the cluster source temperature r0 ( PO=20 bar in all experiments). The observed potential shift Eb is attributed to the surface barrier for penetration of the electrons into the cluster. From the known dependence of& on density the core densities of the helium clusters is estimated to vaq between n = I .2 x lO*l cmm3 and n= 2.2 X 10" cm-' for r,= 14.9 and 11 K, respeclively. The latter values agree with those for bulk liquid helium. For Ne clusters, &,=0.7 kO.3 eV independent of the source conditions.