Vacuum ultraviolet
Definition and meaning of Vacuum ultraviolet in chemistry.
Vacuum ultraviolet (VUV) is electromagnetic radiation with wavelengths between approximately 10 and 200 nanometers. These short wavelengths correspond to photon energies high enough to ionize most atoms and break chemical bonds, yet are readily absorbed by oxygen and nitrogen in air.
In more detail
Because atmospheric gases absorb VUV radiation, practical use requires a vacuum or ultra-high vacuum environment, which distinguishes it from regular ultraviolet light. The high photon energy (approximately 6 to 120 electron volts) makes VUV particularly valuable for spectroscopy, enabling researchers to directly measure atomic and molecular ionization potentials. VUV light is produced by synchrotrons, discharge lamps such as helium or argon lamps, and excimer lasers. Applications include semiconductor photolithography, material analysis, and fundamental studies of atomic and molecular electronic structure.
Key facts
| Field | Physical Chemistry |
|---|---|
| Wavelength range | 10-200 nanometers |
| Photon energy | Approximately 6-120 electron volts |
| Key property | Strongly absorbed by atmospheric gases; requires vacuum environment |
In synchrotron-based photoelectron spectroscopy, VUV light ionizes atoms in a sample, and scientists measure the kinetic energy of the ejected electrons to determine ionization energies and orbital structure.
Frequently asked questions
Why is it called vacuum ultraviolet?
VUV radiation is strongly absorbed by oxygen and nitrogen in air, so containment in a vacuum is necessary to prevent the light from being absorbed before reaching its target sample or detector.
How is VUV different from regular UV light?
VUV has shorter wavelengths (10-200 nm), much higher photon energies, and cannot propagate through air. Regular UV light (200-400 nm) can be used in atmospheric conditions but VUV requires a vacuum environment.