photoelectronic

Photoelectronic is an adjective describing phenomena, effects, and devices in which light interacts with electrons, particularly when photons eject electrons from a material or alter their energy states. The term is commonly used to refer to photoelectric processes and to devices that operate through photoemission or photoconduction.

The foundational concept is the photoelectric effect. When light with sufficient energy shines on a material, electrons can be emitted. Albert Einstein showed that light consists of quanta called photons, and emission occurs when hf exceeds the work function of the material. The kinetic energy of the emitted electrons is hf minus the work function, and the effect provides evidence for the quantum nature of light.

In solids, photoelectronic techniques, such as photoelectron spectroscopy (XPS, UPS, ARPES), probe electronic structure, chemical composition, and surface states by analyzing emitted electrons as a function of energy and angle.

Photoelectronic devices include photodetectors, photoelectric cells, and photomultiplier tubes, which convert light into electrical signals via photoemission or photoconduction. Vacuum-tube devices rely directly on photoemission from a photocathode, while semiconductor photodiodes and solar cells use electron-hole pairs or internal photoemission mechanisms to produce current.

Key factors affecting photoelectronic processes are the material work function, surface condition, light wavelength and intensity, and the quantum efficiency of emission or detection. The field spans basic physics, surface science, and detector technology and continues to advance with ultrafast laser techniques and nanoscale photoemission studies.