Abstract

A 10 eV to 200 eV electron beam with currents up to 30 µA was used to bombard a LiF single crystal surfaces. The electron beam axis was incident on the target under 45°. The bombarding area had dimensions of approximately 2 by 4 mm. Careful investigations have been done to measure the profile of the electron beam. Radiation of excited states was collimated by a MgF₂ lens into a high resolution one meter grating monochromator viewing the crystal surface perpendicularly. Ground state Li atoms have been measured with a quadrupole mass analyzer. The UHV-system maintained a base pressure of less than 3xl0⁻¹⁰ mbar during the measurements. Sample charging, which is a crucial problem with insulators especially at low temperatures, was largely reduced by placing a Mo-mesh with a transmission of 80% over the crystal surface and by using low current densities.

© 1989 Optical Society of America