Photoemission

Article By:

Apker, L. Formerly, General Electric Research Laboratory, Schenectady, New York.

Tansu, Nelson Department of Electrical and Computer Engineering, Center for Optical Technologies, Rossin College of Engineering and Applied Science, Lehigh University, Bethlehem, Pennsylvania.

Last reviewed:January 2020

DOI:https://doi.org/10.1036/1097-8542.510000

The ejection of electrons from a solid (or less commonly, a liquid) by incident electromagnetic radiation. Photoemission is also referred to as the external photoelectric effect. The visible and ultraviolet regions of the electromagnetic spectrum are most often involved, although the infrared and x-ray regions are also of interest. Photoemission has several distinguishing experimental features: (1) the process of photon absorption and photoelectron generation is instantaneous, that is, there is no detectable time lag; (2) at a given frequency the number of photoelectrons ejected per second is proportional to the intensity of the incident radiation; and (3) the kinetic energies of the photoelectrons depend on the incident photon frequency and the work function of the surface, but are independent of the incident intensity.

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