Multiple scattering effects on quantum efficiency and response time for cesiated metal photocathodes

An oft used approximation to predict quantum efficiency (QE) from bare metals or those with a low work function coating such as cesium is to assume that photo-excited electrons have not scattered prior to their emission. Monte Carlo simulations are used to assess that approximation, and show that, w...

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Veröffentlicht in:Journal of applied physics 2011-08, Vol.110 (3), p.034504-034504-13
Hauptverfasser: Jensen, Kevin L., Montgomery, Eric J., Feldman, Donald W., O'Shea, Patrick G., Harris, John R., Lewellen, John W., Moody, Nathan
Format: Artikel
Sprache:eng
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Zusammenfassung:An oft used approximation to predict quantum efficiency (QE) from bare metals or those with a low work function coating such as cesium is to assume that photo-excited electrons have not scattered prior to their emission. Monte Carlo simulations are used to assess that approximation, and show that, while good for bare metals, for cesiated metals a photoexcited electron may undergo several scattering events and yet be emitted. Neglecting scattered electrons therefore underestimates QE. Emitted electrons that have undergone scattering before emission elongate the response time by giving rise to a long time tail, low energy contribution to the faster non-scattered emission, for which a model is developed. The theory is applied to study variations in QE as a function of wavelength measured from cesiated metal surfaces. The extension of the findings to semiconductor photocathodes is briefly discussed.
ISSN:0021-8979
1089-7550
DOI:10.1063/1.3610397