Fotoionizáció

Fotoionizáció, also known as photoionization, is the physical process by which an atom or molecule absorbs one or more photons of electromagnetic radiation and is subsequently ionized. This means that an electron is ejected from the atom or molecule, resulting in the formation of a positively charged ion. The energy of the absorbed photon must be greater than or equal to the ionization energy of the atom or molecule for photoionization to occur.

The process can be described by Einstein's photoelectric effect, where a photon's energy is used to overcome the binding energy of an electron and provide it with kinetic energy. In photoionization, the outgoing electron carries away the excess energy. The wavelength of the incident radiation is a key factor; shorter wavelengths (higher energy photons) are more likely to cause photoionization.

Fotoionizáció is a fundamental process in various fields of physics and chemistry. It plays a significant role in atmospheric science, where solar ultraviolet radiation ionizes molecules in the Earth's upper atmosphere, forming the ionosphere. In astrophysics, photoionization is crucial for understanding the formation and evolution of stars and galaxies, as it influences the ionization state of interstellar gas. Spectroscopic techniques often utilize photoionization to study the electronic structure of atoms and molecules, and it is also employed in plasma generation and mass spectrometry. The cross-section for photoionization, which quantifies the probability of the process occurring, depends on the photon energy and the specific atom or molecule.