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Resonance-Enhanced Two-Photon Ionization of Ions by Lyman alpha Radiation in Gaseous Nebulae

Johansson, Sveneric LU and Letokhov, Vladilen LU (2001) In Science 291(5504). p.625-627
Abstract
One of the mysteries of nebulae in the vicinity of bright stars is theappearance of bright emission spectral lines of ions, which imply fairlyhigh excitation temperatures. We suggest that an ion formationmechanism, based on resonance-enhanced two-photon ionization (RETPI) byintense H Lyman alpha radiation (wavelength of 1215 angstroms) trappedinside optically thick nebulae, can produce these spectral lines. Therate of such an ionization process is high enough for rarefied gaseousmedia where the recombination rate of the ions formed can be10<SUP>-6</SUP> to 10<SUP>-8</SUP> per second for an electron density of10<SUP>3</SUP> to 10<SUP>5</SUP> per cubic centimeter in the nebula.Under such... (More)
One of the mysteries of nebulae in the vicinity of bright stars is theappearance of bright emission spectral lines of ions, which imply fairlyhigh excitation temperatures. We suggest that an ion formationmechanism, based on resonance-enhanced two-photon ionization (RETPI) byintense H Lyman alpha radiation (wavelength of 1215 angstroms) trappedinside optically thick nebulae, can produce these spectral lines. Therate of such an ionization process is high enough for rarefied gaseousmedia where the recombination rate of the ions formed can be10<SUP>-6</SUP> to 10<SUP>-8</SUP> per second for an electron density of10<SUP>3</SUP> to 10<SUP>5</SUP> per cubic centimeter in the nebula.Under such conditions, the photo-ions formed may subsequently undergofurther RETPI, catalyzed by intense He I and He II radiation, which alsogets enhanced in optically thick nebulae that contain enough helium. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Science
volume
291
issue
5504
pages
625 - 627
publisher
The American Association for the Advancement of Science
external identifiers
  • Scopus:0035951487
ISSN
1095-9203
DOI
10.1126/science.291.5504.625
language
English
LU publication?
yes
id
379baa15-e13d-4f04-b123-52c2c146afbf (old id 130251)
date added to LUP
2007-07-13 12:22:10
date last changed
2016-10-13 04:42:25
@misc{379baa15-e13d-4f04-b123-52c2c146afbf,
  abstract     = {One of the mysteries of nebulae in the vicinity of bright stars is theappearance of bright emission spectral lines of ions, which imply fairlyhigh excitation temperatures. We suggest that an ion formationmechanism, based on resonance-enhanced two-photon ionization (RETPI) byintense H Lyman alpha radiation (wavelength of 1215 angstroms) trappedinside optically thick nebulae, can produce these spectral lines. Therate of such an ionization process is high enough for rarefied gaseousmedia where the recombination rate of the ions formed can be10&lt;SUP&gt;-6&lt;/SUP&gt; to 10&lt;SUP&gt;-8&lt;/SUP&gt; per second for an electron density of10&lt;SUP&gt;3&lt;/SUP&gt; to 10&lt;SUP&gt;5&lt;/SUP&gt; per cubic centimeter in the nebula.Under such conditions, the photo-ions formed may subsequently undergofurther RETPI, catalyzed by intense He I and He II radiation, which alsogets enhanced in optically thick nebulae that contain enough helium.},
  author       = {Johansson, Sveneric and Letokhov, Vladilen},
  issn         = {1095-9203},
  language     = {eng},
  number       = {5504},
  pages        = {625--627},
  publisher    = {ARRAY(0x911af88)},
  series       = {Science},
  title        = {Resonance-Enhanced Two-Photon Ionization of Ions by Lyman alpha Radiation in Gaseous Nebulae},
  url          = {http://dx.doi.org/10.1126/science.291.5504.625},
  volume       = {291},
  year         = {2001},
}