The Lyman and Werner Band Systems of Molecular Hydrogen

Abgrall, H.; Roueff, E.; Launay, Françoise; Roncin, Jean-Yves; Subtil, J. L.

doi:10.1006/jmsp.1993.1040

Cited by 198 publications

(257 citation statements)

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“…We use the compilation of Morton (2003) for the atomic data and the ones by Abgrall et al (1993aAbgrall et al ( , 1993b for the H 2 data. For each star, A, C, and P denote transitions that are used with the AOD, COG, and PF methods, respectively.…”

Section: Discussionmentioning

confidence: 99%

Variations in D/H and D/O from NewFar Ultraviolet Spectroscopic ExplorerObservations

Oliveira

Moos

Chayer

et al. 2006

ApJ

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We use data obtained with the Far Ultraviolet Spectroscopic Explorer (FUSE ) to determine the interstellar abundances of D i, N i, O i, Fe ii, and H 2 along the sight lines to WD 1034+001, BD +39 3226, and TD1 32709. Our main focus is on determining the D/ H, N/ H, O/ H, and D/O ratios along these sight lines, with log N (H) > 20:0, that probe gas well outside of the Local Bubble. for the WD 1034+001, BD +39 3226, and TD1 32709 sight lines, respectively (all 1 ). The scatter in these three D/ H ratios exemplifies the scatter that has been found by other authors for sight lines with column densities in the range 19:2 < log N (H) < 20:7. The D/H ratio toward WD 1034+001 and all of the D/O ratios derived here are inconsistent with the Local Bubble value and are some of the highest in the literature. We discuss the implications of our measurements for the determination of the present-epoch abundance of deuterium and for the different scenarios that try to explain the D/H variations. We present a study of D/H as a function of the average sight line gas density, using the ratios derived in this work as well as ratios from the literature, which suggests that D/ H decreases with increasing gas volume density. Similar behaviors by other elements such as Fe and Si have been interpreted as the result of depletion into dust grains.

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Section: Discussionmentioning

confidence: 99%

Variations in D/H and D/O from NewFar Ultraviolet Spectroscopic ExplorerObservations

Oliveira

Moos

Chayer

et al. 2006

ApJ

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“…In contrast to singlet states of ungerade symmetry, for which spectral data were available from classical VUV absorption studies, [10][11][12] singlet gerade states do not have dipole-allowed transitions to the X 1 ⌺ g ϩ ground state. Therefore the excited gerade states were merely observed in discharges, where transitions between excited states may occur.…”

Section: Introductionmentioning

confidence: 94%

Observation of the I′ 1Πg outer well state in H2 and D2

Reinhold

Lange

Hogervorst

et al. 1998

The Journal of Chemical Physics

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We observed bound levels of the IЈ state in H 2 and D 2 , confined in the outer well of the lowest 1 ⌸ g adiabatic potential close to its (1sϩ2p) dissociation limit, with an equilibrium internuclear distance of Ϸ8 a.u. Rovibronic levels (vϭ0 -2, Jϭ1 -5 for H 2 and vϭ0 -5, Jϭ1 -6 for D 2 ) are populated with pulsed lasers in resonance enhanced XUVϩIR ͑extreme ultravioletϩinfrared͒ excitation, and probed by a third laser pulse. Level energies are measured with an accuracy of Ϸ0.03 cm Ϫ1 , and are in reasonable agreement with predictions from ab initio calculations in adiabatic approximation; the smallness of ⌳-doublet splitting indicating that nonadiabatic interactions with 1 ⌺ g ϩ states are generally weak. Additional resonances are observed close to the nϭ2 dissociation limit, some of which can be assigned as high vibrational levels of the EF 1 ⌺ g ϩ state.

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“…Initial curves of growth were constructed from the equivalentwidth measurements using the wavelengths and oscillator strengths from Abgrall et al (1993aAbgrall et al ( , 1993b. We required at least two unblended lines for these curves.…”

Section: Curve Of Growth For the Molecular Hydrogen Absorption Componmentioning

confidence: 99%

Molecular and Atomic Excitation Stratification in the Outflow of the Planetary Nebula M27

McCandliss¹,

France²,

Lupu³

et al. 2007

ApJ

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High-resolution spectroscopy with FUSE and HST STIS of atomic and molecular velocity stratification in the nebular outflow of M27 challenge models of the abundance kinematics in planetary nebulae. The simple picture of a very high speed ($1000 km s À1 ), high-ionization, radiation-driven stellar wind surrounded by a slower ($10 km s À1 ) mostly molecular outflow, with low-ionization and neutral atomic species residing at the wind interaction interface, is not supported. Instead, we find vibrationally excited H 2 intermixed with mostly neutral atomic species at a transition velocity (33 km s À1 ) between a fast (33Y65 km s À1 ) low-ionization zone and a slow (P33 km s À1 ) high-ionization zone. Ly fluorescence of H 2 has been detected, but far-UV continuum fluorescence has not. The diffuse nebular medium is inhospitable to molecules and dust. Maintaining a modest equilibrium abundance of H 2 [N (H 2 )/N (H i)T1] in the diffuse nebular medium requires a source of H 2 , mostly likely the clumpy nebular medium. The stellar SED shows no sign of reddening [E(B À V ) < 0:01], but paradoxically H /H indicates E(B À V ) $ 0:1. The enhancement of H /H in the absence of dust may result from a two-step process of H 2 ionization by Lyman continuum photons followed by dissociative recombination [ H 2 + ! H þ 2 + e À ! H(1s) + H(nl )], which ultimately produces fluorescence of H and Ly . In the optically thin limit at the inferred radius of the velocity transition, we find that dissociation of H 2 by stellar Lyman continuum photons is an order of magnitude more efficient than spontaneous dissociation by far-UV photons. The importance of this H 2 destruction process in H ii regions has been overlooked.

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The Lyman and Werner Band Systems of Molecular Hydrogen

Cited by 198 publications

References 0 publications

Variations in D/H and D/O from NewFar Ultraviolet Spectroscopic ExplorerObservations

Variations in D/H and D/O from NewFar Ultraviolet Spectroscopic ExplorerObservations

Observation of the I′ 1Πg outer well state in H2 and D2

Molecular and Atomic Excitation Stratification in the Outflow of the Planetary Nebula M27

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