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Erschienen in:
2018 | OriginalPaper | Buchkapitel
75. Photoelectron Yield Spectroscopy
verfasst von : Hisao Ishii
Erschienen in: Compendium of Surface and Interface Analysis
Verlag: Springer Singapore
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Abstract
PYS is a method to measure the ionization energy of materials (work function in the case of metals) by using photoemission process. A sample surface is irradiated by tunable UV light, and the number of emitted photoelectrons is measured. The quantum yield of photoelectron (Y), which is the number of emitted photoelectrons per photon absorbed, is detected as a function of incident photon energy (hν). The principle is shown in Fig. 75.1 for the case of a material with an energy gap. When hν becomes greater than the threshold ionization energy (Ith) during incremental hν scan, the value of Y starts to increase. Thus, by determining the threshold of the spectrum, the value of Ith can be evaluated. In the case of metal sample, the work function of the sample can be deduced in the similar way.