Absorption coefficients for hydrogen—III. calculated pressure-induced H2-H vibrational absorption in the fundamental region

Patch, R. W.

doi:10.1016/0022-4073(74)90003-x

Cited by 6 publications

(4 citation statements)

References 12 publications

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“…The calculations are quantum mechanical and the isotropic potential approximation has been applied. The computed absorption in the fundamental band agrees roughly with the one determined by Patch (1974). However, the absorption in the translational band, which has not been obtained before, is significantly stronger than in the fundamental band.…”

supporting

confidence: 76%

“…Accordingly, at the temperatures considered, most of the black body radiation falls in the high absorption part of the spectrum. The fundamental band absorption was modeled by Patch (1974) and we note that the absorption calculated here is of similar intensity. However, the translational band absorption is about one order of magnitude stronger than that of the fundamental band and appears to be important to include in modeling of star atmospheres.…”

mentioning

confidence: 99%

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The H₂–H infrared absorption bands at temperatures from 1000 K to 2500 K

Gustafsson¹,

Frommhold²

2003

A&A

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Abstract. H 2 -H collision-induced absorption spectra are computed for temperatures from 1000 K to 2500 K and frequencies from 100 cm −1 to 10 000 cm −1 . The calculations are quantum mechanical and the isotropic potential approximation has been applied. The computed absorption in the fundamental band agrees roughly with the one determined by Patch (1974). However, the absorption in the translational band, which has not been obtained before, is significantly stronger than in the fundamental band.Key words. molecular processes -infrared: stars -line: profiles -radiation mechanisms: thermal -scatteringstars: atmospheres Colliding atoms or molecules acquire a transient electric dipole moment even if the non-interacting (i.e., well separated) individual atoms or molecules are nonpolar. As a consequence, at high enough gas densities, collision-induced infrared absorption is observed, even if at lower densities the corresponding gases and gas mixtures are infrared-inactive (Welsh 1972;Frommhold 1993). Collision-induced absorption of compressed, nonpolar gases and gas mixtures, such as hydrogen, were discovered by Welsh et al. (1949) and their significance for astrophysics was almost instantly recognized (Welsh 1972;Herzberg 1952a;Herzberg 1952b;Trafton 1964). Since then, extensive investigations of collision-induced absorption in planetary atmospheres and, more recently, in the atmospheres of certain cool stars (Borysow et al. 1997;Burrows et al. 1997;Jørgensen et al. 2000) have been carried out.Whereas for systems such as H 2 -H 2 and H 2 -He a number of excellent laboratory measurements of the collision-induced spectra exist that permit stringent tests of the quantum chemical computations (Frommhold 1993), no such measurements are known for the H 2 -H system and its spectra are obtained from theory. This is similar to the H-He pair, which also has been investigated theoretically (Gustafsson & Frommhold 2001). The absorption due to H 2 -H pairs could be important for the dynamics of the atmospheres of stars, when temperatures are such that atomic and molecular hydrogen coexist. Opacities of zero-metallicity gas were thoroughly investigated by Lenzuni et al. (1991). Collision-induced absorption is in general most important at the lowest of the temperatures considered there, namely 3000 K. At higher temperatures there are other strong Send offprint requests to: M. Gustafsson, e-mail: magnus@physics.utexas.edu continuum absorbers, such as ionic hydrogen. It is at temperatures below 3000 K and at relatively low pressures (for significant atomic hydrogen abundance) that we anticipate the H 2 -H collision-induced absorption to be important.We have employed quantum calculations (Frommhold 1993) of the absorption spectra of H 2 -H collisional pairs at temperatures from 1000 K to 2500 K. This is a range of temperatures where atomic hydrogen is abundant under pressures which could be of interest. For the modeling of stellar atmospheres, the maximum of the Planck distribution of black body radiation should be considered, or rat...

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supporting

confidence: 76%

mentioning

confidence: 99%

The H₂–H infrared absorption bands at temperatures from 1000 K to 2500 K

Gustafsson¹,

Frommhold²

2003

A&A

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“…8.1 and 8.2 absorption by H 2 pairs in the fundamental band at T D 1;000 K and T D 3;000 K as computed ab initio by Borysow and Frommhold (1990) are compared with results obtained by the same authors using the approximate spectral function. We also show earlier estimates by Linsky (1969) and Patch (1971). 13 The super-and subscripts ss 0 and M 1 M 2 M M L that should be attached to all X, Y , , and M are omitted to avoid complex notation.…”

Section: Diatomic Gas Pairs (Eg H 2 -H 2 )mentioning

confidence: 99%

“…(8.34a) and (8.34b). Earlier estimates by Linsky (1969) are shown by the dot-dash line, and by Patch (1971) Borysow and Frommhold 1990) An improved, more "user friendly" model of the line profile is described by Birnbaum and Borysow (1991), who derive a correction term significant in the profile wing when the potentials V v and V v 0 are not the same.…”

Section: Diatomic Gas Pairs (Eg H 2 -H 2 )mentioning

confidence: 99%