%0 Journal Article %1 0067-0049-138-1-229 %A Liu, Xianming %A Shemansky, Donald E. %A Abgrall, H. %A Roueff, E. %A Dziczek, D. %A Hansen, D. L. %A Ajello, J. M. %D 2002 %J The Astrophysical Journal Supplement Series %K electron impact resolved time %N 1 %P 229 %T Time-resolved Electron Impact Study of Excitation of H2 Singlet-Gerade States from Cascade Emission in the Vacuum Ultraviolet Region %U http://stacks.iop.org/0067-0049/138/i=1/a=229 %V 138 %X Medium-resolution (full width at half-maximum Δλ = 0.5 Å) vacuum ultraviolet (VUV) emission spectra of H 2 from forbidden excitation to the excited singlet- gerade states and subsequent cascade to the singlet- ungerade states have been studied with a time-resolved electron-impact technique. Emissions from the B 1 Σ ##IMG## http://ej.iop.org/images/0067-0049/138/1/229/img1.gif img1.gif , C 1 Π u , B' 1 Σ ##IMG## http://ej.iop.org/images/0067-0049/138/1/229/img1.gif img1.gif , and D 1 Π u states that are entirely due to cascade from the singlet- gerade states have been observed. Lyman band emission intensities dominate over the entire 940-1650 Å wavelength region, though Werner band emission intensities are also significant. In addition, very weak cascade emissions from the v j = 0 and 1 levels of the B' 1 Σ ##IMG## http://ej.iop.org/images/0067-0049/138/1/229/img1.gif img1.gif and D 1 Π u states are also evident. In contrast to previous assumption, the cascade excitation is observed to take place over all the vibrational levels of the B 1 Σ ##IMG## http://ej.iop.org/images/0067-0049/138/1/229/img1.gif img1.gif and C 1 Π u states, while contributing heavily to low v j levels of the B 1 Σ ##IMG## http://ej.iop.org/images/0067-0049/138/1/229/img1.gif img1.gif state. Synthetic spectra based on the calculated transition probabilities of the EF 1 Σ ##IMG## http://ej.iop.org/images/0067-0049/138/1/229/img2.gif img2.gif , GK 1 Σ ##IMG## http://ej.iop.org/images/0067-0049/138/1/229/img2.gif img2.gif , H ##IMG## http://ej.iop.org/images/0067-0049/138/1/229/img3.gif img3.gif 1 Σ ##IMG## http://ej.iop.org/images/0067-0049/138/1/229/img2.gif img2.gif , I 1 Π g , J 1 Δ g , O 1 Σ ##IMG## http://ej.iop.org/images/0067-0049/138/1/229/img2.gif img2.gif and P 1 Σ ##IMG## http://ej.iop.org/images/0067-0049/138/1/229/img2.gif img2.gif ##IMG## http://ej.iop.org/icons/Entities/longrightarrow.gif longrightarrow B 1 Σ ##IMG## http://ej.iop.org/images/0067-0049/138/1/229/img1.gif img1.gif , C 1 Π u , B' 1 Σ ##IMG## http://ej.iop.org/images/0067-0049/138/1/229/img1.gif img1.gif , and D 1 Π u band systems and Franck-Condon factors of the EF 1 Σ ##IMG## http://ej.iop.org/images/0067-0049/138/1/229/img2.gif img2.gif - X 1 Σ ##IMG## http://ej.iop.org/images/0067-0049/138/1/229/img2.gif img2.gif , GK  1 Σ ##IMG## http://ej.iop.org/images/0067-0049/138/1/229/img2.gif img2.gif - X 1 Σ ##IMG## http://ej.iop.org/images/0067-0049/138/1/229/img2.gif img2.gif , H ##IMG## http://ej.iop.org/images/0067-0049/138/1/229/img3.gif img3.gif 1 Σ ##IMG## http://ej.iop.org/images/0067-0049/138/1/229/img2.gif img2.gif - X 1 Σ ##IMG## http://ej.iop.org/images/0067-0049/138/1/229/img2.gif img2.gif , I 1 Π g - X 1 Σ ##IMG## http://ej.iop.org/images/0067-0049/138/1/229/img2.gif img2.gif , J 1 Δ g - X 1 Σ ##IMG## http://ej.iop.org/images/0067-0049/138/1/229/img2.gif img2.gif , O 1 Σ ##IMG## http://ej.iop.org/images/0067-0049/138/1/229/img2.gif img2.gif - X 1 Σ ##IMG## http://ej.iop.org/images/0067-0049/138/1/229/img2.gif img2.gif , and P 1 Σ ##IMG## http://ej.iop.org/images/0067-0049/138/1/229/img2.gif img2.gif - X 1 Σ ##IMG## http://ej.iop.org/images/0067-0049/138/1/229/img2.gif img2.gif are in good agreement with the observed Lyman and Werner band intensities. The present study shows that a number of singlet- gerade and singlet- ungerade states are involved in the cascade excitation process of H 2 . The cascade from these states in the VUV provide diagnostic information on astrophysical sources for H 2 emission.

@article{0067-0049-138-1-229, abstract = {Medium-resolution (full width at half-maximum Δλ = 0.5 Å) vacuum ultraviolet (VUV) emission spectra of H 2 from forbidden excitation to the excited singlet- gerade states and subsequent cascade to the singlet- ungerade states have been studied with a time-resolved electron-impact technique. Emissions from the B 1 Σ ##IMG## [http://ej.iop.org/images/0067-0049/138/1/229/img1.gif] {img1.gif} , C 1 Π u , B' 1 Σ ##IMG## [http://ej.iop.org/images/0067-0049/138/1/229/img1.gif] {img1.gif} , and D 1 Π u states that are entirely due to cascade from the singlet- gerade states have been observed. Lyman band emission intensities dominate over the entire 940-1650 Å wavelength region, though Werner band emission intensities are also significant. In addition, very weak cascade emissions from the v j = 0 and 1 levels of the B' 1 Σ ##IMG## [http://ej.iop.org/images/0067-0049/138/1/229/img1.gif] {img1.gif} and D 1 Π u states are also evident. In contrast to previous assumption, the cascade excitation is observed to take place over all the vibrational levels of the B 1 Σ ##IMG## [http://ej.iop.org/images/0067-0049/138/1/229/img1.gif] {img1.gif} and C 1 Π u states, while contributing heavily to low v j levels of the B 1 Σ ##IMG## [http://ej.iop.org/images/0067-0049/138/1/229/img1.gif] {img1.gif} state. Synthetic spectra based on the calculated transition probabilities of the EF 1 Σ ##IMG## [http://ej.iop.org/images/0067-0049/138/1/229/img2.gif] {img2.gif} , GK 1 Σ ##IMG## [http://ej.iop.org/images/0067-0049/138/1/229/img2.gif] {img2.gif} , H ##IMG## [http://ej.iop.org/images/0067-0049/138/1/229/img3.gif] {img3.gif} 1 Σ ##IMG## [http://ej.iop.org/images/0067-0049/138/1/229/img2.gif] {img2.gif} , I 1 Π g , J 1 Δ g , O 1 Σ ##IMG## [http://ej.iop.org/images/0067-0049/138/1/229/img2.gif] {img2.gif} and P 1 Σ ##IMG## [http://ej.iop.org/images/0067-0049/138/1/229/img2.gif] {img2.gif} ##IMG## [http://ej.iop.org/icons/Entities/longrightarrow.gif] {longrightarrow} B 1 Σ ##IMG## [http://ej.iop.org/images/0067-0049/138/1/229/img1.gif] {img1.gif} , C 1 Π u , B' 1 Σ ##IMG## [http://ej.iop.org/images/0067-0049/138/1/229/img1.gif] {img1.gif} , and D 1 Π u band systems and Franck-Condon factors of the EF 1 Σ ##IMG## [http://ej.iop.org/images/0067-0049/138/1/229/img2.gif] {img2.gif} - X 1 Σ ##IMG## [http://ej.iop.org/images/0067-0049/138/1/229/img2.gif] {img2.gif} , GK  1 Σ ##IMG## [http://ej.iop.org/images/0067-0049/138/1/229/img2.gif] {img2.gif} - X 1 Σ ##IMG## [http://ej.iop.org/images/0067-0049/138/1/229/img2.gif] {img2.gif} , H ##IMG## [http://ej.iop.org/images/0067-0049/138/1/229/img3.gif] {img3.gif} 1 Σ ##IMG## [http://ej.iop.org/images/0067-0049/138/1/229/img2.gif] {img2.gif} - X 1 Σ ##IMG## [http://ej.iop.org/images/0067-0049/138/1/229/img2.gif] {img2.gif} , I 1 Π g - X 1 Σ ##IMG## [http://ej.iop.org/images/0067-0049/138/1/229/img2.gif] {img2.gif} , J 1 Δ g - X 1 Σ ##IMG## [http://ej.iop.org/images/0067-0049/138/1/229/img2.gif] {img2.gif} , O 1 Σ ##IMG## [http://ej.iop.org/images/0067-0049/138/1/229/img2.gif] {img2.gif} - X 1 Σ ##IMG## [http://ej.iop.org/images/0067-0049/138/1/229/img2.gif] {img2.gif} , and P 1 Σ ##IMG## [http://ej.iop.org/images/0067-0049/138/1/229/img2.gif] {img2.gif} - X 1 Σ ##IMG## [http://ej.iop.org/images/0067-0049/138/1/229/img2.gif] {img2.gif} are in good agreement with the observed Lyman and Werner band intensities. The present study shows that a number of singlet- gerade and singlet- ungerade states are involved in the cascade excitation process of H 2 . The cascade from these states in the VUV provide diagnostic information on astrophysical sources for H 2 emission.}, added-at = {2010-05-16T14:07:11.000+0200}, author = {Liu, Xianming and Shemansky, Donald E. and Abgrall, H. and Roueff, E. and Dziczek, D. and Hansen, D. L. and Ajello, J. M.}, biburl = {https://www.bibsonomy.org/bibtex/2fa482fc90145896cec679701202c28f5/gensemer}, description = {Time-resolved Electron Impact Study of Excitation of H2 Singlet-Gerade States from Cascade Emission in the Vacuum Ultraviolet Region}, interhash = {8665e563e0b2811ddf393039065a80d0}, intrahash = {fa482fc90145896cec679701202c28f5}, journal = {The Astrophysical Journal Supplement Series}, keywords = {electron impact resolved time}, number = 1, pages = 229, timestamp = {2010-05-16T14:07:11.000+0200}, title = {Time-resolved Electron Impact Study of Excitation of H2 Singlet-Gerade States from Cascade Emission in the Vacuum Ultraviolet Region}, url = {http://stacks.iop.org/0067-0049/138/i=1/a=229}, volume = 138, year = 2002 }