The absorption spectrum of H2: CRDS measurements of the (2-0) band, review of the literature data and accurate ab initio line list up to 35 000 cm−1

2012 ◽  
Vol 14 (2) ◽  
pp. 802-815 ◽  
Author(s):  
Alain Campargue ◽  
Samir Kassi ◽  
Krzysztof Pachucki ◽  
Jacek Komasa
Keyword(s):  
Absorption Spectrum ◽  
Ab Initio ◽  
Review Of The Literature ◽  
Line List

Extensions to the spectrum of doubly excited Mg I in the vacuum ultraviolet

1978 ◽  
Vol 364 (1718) ◽  
pp. 353-366 ◽  
Keyword(s):  
Absorption Spectrum ◽  
Ab Initio ◽  
Electron Impact ◽  
Vacuum Ultraviolet ◽  
Background Radiation ◽  
Valence Shell ◽  
Electron Synchrotron ◽  
Doubly Excited ◽  
High Series ◽  
The Continuum

The absorption spectrum of Mg I vapour between 2000 and 700 ņ has been reinvestigated, using the continuum emitted by the Bonn 500 MeV electron synchrotron as the source of background radiation. Extensions to the double excitation spectrum of the valence shell have resulted and are compared with recent data obtained by electron impact spectroscopy. Ab initio calculations of the doubly excited configurations have been extended to high series members, and the transition from LS to jj coupling is shown to be responsible for the appearance of a 1 S 0 - 3 P 1 series not previously detected by photoabsorption.

scholarly journals Opacity Data for HCN and HNC from a New Ab Initio Line List

2002 ◽  
Vol 578 (1) ◽  
pp. 657-663 ◽  
Author(s):  
Gregory J. Harris ◽  
Oleg L. Polyansky ◽  
Jonathan Tennyson
Keyword(s):  
Ab Initio ◽  
Line List

scholarly journals ExoMol line list – XXXIV. A rovibrational line list for phosphinidene (PH) in its $X\, {}^3\Sigma ^-$ and $a\, {}^1\Delta$ electronic states

2019 ◽  
Vol 488 (2) ◽  
pp. 2332-2342 ◽  
Author(s):  
Jonathan Langleben ◽  
Jonathan Tennyson ◽  
Sergei N Yurchenko ◽  
Peter Bernath
Keyword(s):  
Ab Initio ◽  
Electronic States ◽  
Stellar Atmospheres ◽  
Spin Splitting ◽  
Mean Square ◽  
Data Bases ◽  
Line List ◽  
Line Intensities ◽  
Experimental Transition ◽  
Correction Terms

ABSTRACT A rovibronic line list for the ground (X 3Σ−) and first excited (a 1Δ) states of phosphinidene, 31PH, is computed. The line list is designed for studies of exoplanetary and cool stellar atmospheres with temperatures up to 4000 K. A combination of empirical and ab initio data is used to produce the line list: potential energy curves (PECs) are fitted using experimental transition frequencies; these transitions are reproduced with a root mean square error of 0.01 cm−1. The nuclear Schrödinger equation is solved using these PECs plus Born–Oppenheimer and spin splitting correction terms. Line intensities and Einstein   A coefficients are computed using ab initio dipole moment curves for X–X and a–a transitions. The resulting LaTY line list, which contains 65 055 transitions for 2528 rovibronic states up to 24 500 cm −1 and J = 80, is used to simulate spectra in emission and absorption for a range of temperatures. The line list is made available in electronic form at the CDS and ExoMol data bases.

The absorption and emission spectra of HD in the vacuum ultraviolet

1976 ◽  
Vol 54 (5) ◽  
pp. 525-567 ◽  
Author(s):  
I. Dabrowski ◽  
G. Herzberg
Keyword(s):  
Absorption Spectrum ◽  
Ab Initio ◽  
Excited States ◽  
Vacuum Ultraviolet ◽  
Emission Spectra ◽  
Dissociation Limit ◽  
Infinite Mass ◽  
Ab Initio Theory ◽  
Vibrational Constants ◽  
Weak Transitions

The absorption spectrum of HD has been studied under high resolution in the vacuum ultraviolet to 840 Å, the emission spectrum to 1000 Å. The analysis of the latter gives accurate rotational constants and vibrational intervals of the ground state right up to the dissociation limit. Comparing these experimental data with calculations from ab initio theory, agreement to the same extent as was previously found for H2 and D2 is obtained. Extrapolation of the obs. – calc. values from H2 and D2 to infinite mass yields agreement with the recently revised theoretical values to within less than 0.1 for v < 7 and less than 0.5 cm−1 for the whole range of observed v values. The deviations for finite mass (H2 and D2) are clearly due to the non-adiabatic corrections neglected in the ab initio calculations. The results for HD are not halfway between H2 and D2 but are closer to H2. This apparent anomaly can be quantitatively accounted for, on the basis of recent calculations of Wolniewicz, by the effect of additional nonadiabatic corrections caused by the excited Σu states which in HD, unlike H2 and D2, can interact with the ground state.The rotational and vibrational constants of the excited states B1Σu+, C1Πu, and B′1Σu+ show somewhat larger deviations from ab initio values ranging for v0v from 5 to 120 cm−1, just as for H2 and D2. The electronic isotope shift of HD lies approximately half-way between the values of H2 and D2 as expected. In addition to the B–X, C–X, and B′–X systems the absorption spectrum of HD, unlike that of H2 and D2, shows an extensive progression of weak transitions to the double minimum state EF1Σg+ and a few very weak transitions to the G1Σg+ and I1Πg states. For the EF state both levels in the outer minimum (F) and levels above the maximum are observed. The correlation of the six excited states B, C, B′, EF, G, and I to the two close-lying dissociation limits corresponding to H + D* and H* + D is briefly discussed.

Infrared spectra of tautomers and rotamers of 9-methylguanine. An experimental and theoretical study

1991 ◽  
Vol 69 (11) ◽  
pp. 1705-1720 ◽  
Author(s):  
K. Szczepaniak ◽  
M. Szczesniak ◽  
W. Szajda ◽  
W. B. Person ◽  
J. Leszczynski
Keyword(s):  
Absorption Spectrum ◽  
Ab Initio ◽  
Infrared Spectra ◽  
Electronic Absorption ◽  
Ab Initio Calculation ◽  
Theoretical Study ◽  
Free Energies ◽  
Argon Matrix ◽  
Tautomeric Forms ◽  
Infrared Studies

Both amino-oxo and amino-hydroxy tautomeric forms of 9-methylguanine have been identified in approximately equal abundance in. infrared studies of these molecules isolated in the hydrophobic environment of an argon matrix at 12 K. The amino-hydroxy tautomer occurs in two different rotamers correlated with the rotation of the OH group. The ratio of concentrations of the two rotamers is sensitive to UV irradiation, and this ratio then relaxes to an equilibrium value after irradiation is stopped. This sensitivity allows us to separate the experimental spectra related to the oxo tautomer and to each of the rotamers of the hydroxy tautomer. The relative concentrations of the amino-oxo and amino-hydroxy tautomers ([a-o]/[a-h] = K(o-h) = 1.0 ± 0.3) and of the two rotamers (K(h1-h2) = 0.31 ± 0.10 in an argon matrix at 12 K and about 30 ± 15 in the vapor at 470 K) are estimated from the observed relative infrared absorbances. From these relative concentrations the differences between the free energies of the tautomers (ΔG470 (o-h) = 0 ± 0.5 kJ mol−1) and of the two rotamers (ΔG(h1-h2) = 0.12 ± 0.03 kJ mol−1 in the argon matrix at 12 K and ΔG470 between +2 and −13 kJ mol−1 in the vapor at 470 K) have been estimated. The electronic absorption spectrum of 9-methylguanine isolated in the argon matrix at 12 K and the effect of brief ultraviolet irradiation on it have also been studied. In an effort to interpret the experimental results, ab initio calculations of the infrared spectra have been made for 9-methylguanine at the 3-21G//3-21G level. Comparison with the experimental spectra is of some help with the assignment of the infrared spectra for the different tautomers. Key words: 9-methylguanine, tautomerism, infrared and ultraviolet spectra, matrix isolation, ab initio calculation.

The absorption spectrum of Ag I in the vacuum ultraviolet

1978 ◽  
Vol 361 (1706) ◽  
pp. 379-398 ◽  
Keyword(s):  
Absorption Spectrum ◽  
Synchrotron Radiation ◽  
Variational Method ◽  
Theoretical Prediction ◽  
Ab Initio ◽  
Absorption Spectra ◽  
Vacuum Ultraviolet ◽  
Rydberg Series ◽  
Hartree Fock ◽  
Doubly Excited

The absorption spectrum of Ag I between 550 Å and 1590 Å has been investigated by using synchrotron radiation as the source of continuum. Over 50 new transitions are reported, nearly all of which can be classified into Rydberg series due to excitation of one electron from the 4d subshell. Identifications are made by comparison with previous studies of the arc spectrum as well as with absorption spectra of related elements. Ab initio Hartree-Fock calculations have revealed the importance of treating 5s 5p 1 P based levels by a separate variational method. Doubly excited configurations are also found, but, in contrast to a previous theoretical prediction, double vacancy production within the 4d subshell is not found to be significant for Ag I.

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