photocathode

Thân thiện

A scientist examines a photocathode inside a vacuum tube.

Definition

Noun: A specialized cathode, typically the negatively charged electrode within a vacuum tube or photomultiplier, which emits electrons into the surrounding space when it is exposed to light or other electromagnetic radiation. This emission of electrons due to light exposure is known as the photoelectric effect.

Usage

The word "photocathode" is a technical term used primarily in physics, engineering, and instrumentation. It refers specifically to the light-sensitive component. * The photocathode in the photomultiplier tube is made of a low-work-function material like cesium antimonide. * The device's sensitivity depends heavily on the quantum efficiency of its photocathode. * When light strikes the photocathode, it releases a stream of electrons.

Advanced Usage

• Photocathode response/spectral response: Refers to the efficiency of a photocathode at converting photons of different wavelengths (colors) into electrons.
  • Choosing a photocathode with the correct spectral response is critical for detecting infrared signals.
• Semitransparent photocathode: A type of photocathode where light is incident on one side and electrons are emitted from the opposite side.
  • The image intensifier uses a semitransparent photocathode deposited on the inside of the input window.

Variants and Related Words

• Photoelectric (adjective): Of or relating to the electrical effects of light, especially the emission of electrons.
  • The photoelectric effect is the fundamental principle behind the photocathode.
• Photoelectron (noun): An electron emitted from a material by the photoelectric effect.
  • Each photon absorbed by the photocathode can generate a photoelectron.

Synonyms

• Photoemissive cathode: A more descriptive synonym that explicitly states its function of emitting (emissive) under light (photo).
• Light-sensitive cathode: A simpler, descriptive term.

Related Phrases/Compounds

• Photocathode current: The electric current resulting from the flow of photoelectrons emitted from the photocathode.
  • The measured photocathode current is proportional to the light intensity.
• Photocathode sensitivity: A measure of how effectively a photocathode converts light into an electron current.
  • Advances in material science have greatly improved photocathode sensitivity.

Học thuật

Noun

1. a cathode that emits electrons when illuminated