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Publication Citation: Improved Microwave-discharge Source for uv Photoemission

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Author(s): Theodore V. Vorburger; B Waclawski; D Sandstrom;
Title: Improved Microwave-discharge Source for uv Photoemission
Published: April 01, 1976
Abstract: A microwave-discharge uv light source has been improved to yield significant photon fluxes at 26.9 and 40.81 eV. In order to optimize the 26.9-eV (NeII) and 40.81-eV (HeII) radiation, the discharge was operated at ~2.5 Pa (0.019 Torr) in an external constant magnetic field of ~0.070 T (700 G), which, together with the oscillating electric field of the cavity, produces electron cyclotron resonance. When the discharge conditions were optimized for production of 40.81-eV photons, features near the Fermi energy in the photoemission distribution from W(100) for 40.81-eV photons are approximately 6% as intense as the corresponding features in the distribution for 21.22-eV photons. We estimate that under these conditions the flux of 40.81-eV photons is roughly 50% of the flux of 21.22-eV photons. Photoemission energy distributions with hv = 16.85, 21.22, 26.9, and 40.81 eV have been measured for saturated exposures of CO on W(100) at a temperature of ~80 K. The variation in these data with photon energy is important for making orbital assignments to the energy levels of adsorbed molecular CO.
Citation: Review of Scientific Instruments
Volume: 47
Issue: 4
Pages: pp. 501 - 504
Research Areas: Surface Physics