Exciton Contribution to the Photoemission from Thin Films of Solid Argon

Abstract

The photoelectric yield and the reflectance of solid Ar films on an Au substrate have been measured simultaneously for photon energies 10–30 eV. The thickness ranged from 30–300 Å. The synchrotron radiation of DESY was used as a light source. Even at photon energies below the photoelectric threshold of solid Ar there is some photoemission due to contributions from both the Ar film and the gold substrate. The spectra of the yield per absorbed photon exhibit peaks at the exciton energies. The height of the peaks is almost independent of the film thickness. This indicates that exciton decay at the Ar-vacuum or Ar–Au boundary contributes to photoemission.

Free Exciton Energy Transfer in KrAu Sandwiches

“…Krolikowski and Spicer observed a nearly linear increase of QAu from 0.005 (electrons/photon) at 9 eV to 0.015 a t 11 eV [19]. A similar dependence but with approximately three times larger absolute QAu has been reported by Samson [18] and by us [20]. The evaluation is not sensitive to the absolute value of &Au, except for the absolute value of QET, therefore, the photon energy dependence found for QET (equation (5)) should be reliable but the absolute value may be uncertain by as much as a factor of three.…”

Fast proton-induced electron emission from rare-gas solids and electrostatic charging effects

“…8 With increasing V a the electron emission current reaches a saturation value, but only for thin films as observed previously using photon excitation. 16,17,29,30 In contrast with the I-V a characteristics of the bare gold substrate, which saturates at a few volts, the I-V a curves for the condensed films saturate at relatively high voltages, for instance, approximately 50 V for a 600-Å argon film. The need for a higher saturation voltage indicates that the films charge up to a positive potential during electron emission.…”