Band Spectrum of Chromium Hydride, CrH

Gaydon, A. G.; Pearse, R. W. B.

doi:10.1038/140110a0

Cited by 19 publications

(11 citation statements)

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“…theoretical evidence for a bent 5 Taylor & Francis makes every effort to ensure the accuracy of all the information (the "Content") contained in the publications on our platform. However, Taylor & Francis, our agents, and our licensors make no representations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of the Content.…”

Section: Chromium Dihydride (Crh 2 )mentioning

confidence: 99%

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Chromium dihydride (CrH₂): theoretical evidence for a bent⁵B₂ground state

1995

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Ab initio molecular electronic structure theory has been used to study two likely candidates for the quintet ground state of CrH2 at the self-consistent field, the single and double excitation configuration interaction (CISD), the single and double excitation coupled cluster (CCSD), and the single, double, and perturbative triple excitation coupled cluster (CCSD(T)) levels of theory. The largest basis sets utilized for geometry optimizations, designated two-f TZ2P, have a contraction scheme of Cr(14sl lp6d2f/10s8p3d2f), H(5s2p/3s2p). At the CCSD(T) level of theory using this two-f TZ2P basis, a bent (C2, symmetry) 5B 2 state is predicted to lie a mere 4-2 kcal mol-~ (4-5 kcal mol-1 including zero-point vibrational energy correction) lower in energy than linear (D~oh symmetry) 5X~ HCrH. Theoretical predictions for the equilibrium geometry, harmonic vibrational frequencies, and isotopic frequency shifts of the SB 2 state compare favourably with the results of recent matrix isolation FT-IR work by Xiao, Hauge, and Margrave. The two-f TZ2P CCSD(T) optimized geometry of 5B 2 CrH 2 is r e = 1-658 A and 0 e = 114-4 ~ (118 ~ + 5 ~ is the experimentally estimated bond angle), while the harmonic vibrational frequencies are o91(al) = 1710, ~o2(al) = 582, and to3(b2) = 1683 em-1 (experimentally assigned fundamentals in an argon matrix are the symmetric stretch 1651 cm -t and asymmetric stretch 1615 cm-~). Isotopic frequency shifts of CrD2 relative to CrH 2 are A~o~(al) = -492 and Aco3(b2) = -477 cm-~ (compared with symmetric stretch -462 cm-~ and asymmetric stretch -448-cm-t from experiment).

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Section: Chromium Dihydride (Crh 2 )mentioning

confidence: 99%

“…Diatomic CrH has been the subject of both experimental [5][6][7][8][9][10] and theoretical [11][12][13] investigations. It is known from experiment [10] to have a 6E § ground electronic state (re = 1.6557/~,) which correlates with ground-state 7S chromium and 2S hydrogen atoms in the dissociation limit.…”

Section: Introductionmentioning

confidence: 99%

Chromium dihydride (CrH₂): theoretical evidence for a bent⁵B₂ground state

1995

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“…Although the CrH molecule has been known since 1937 (Gaydon and Pearse 1937), its electronic spectra was poorly characterized until 1993, when Ram and Bernath (1993) performed a rotational analysis of the 0-0 band of the A 6 + -X 6 + transition. The (1, 0) and (1, 1) bands of the A 6 + -X 6 + transitions were remeasured, and an improved set of constants were obtained for the v = 1 vibrational level of the A 6 + state (Bauschlicher et al 2001).…”

mentioning

confidence: 99%

On the effective temperature of large sunspot umbra using CrH sextets electronic state molecular lines

Sriramachandran¹,

Shanmugavel²

2011

Astrophys Space Sci

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A high-resolution spectrum clearly shows the presence of A 6 + -X 6 + (0, 0; 0, 1; 1, 0; 2, 0; 2, 1) and (2, 2) bands system of CrH molecular lines in the spectral range 10,000 cm −1 to 14,050 cm −1 . At least 3928 lines of the six bands, accounting for 57% of the lines registered in the laboratory can be identified with certainty in the sunspot spectrum. Most of the lines are found blended with TiO, CaH, MgH and other atomic species. These molecular lines are typically much more temperature sensitive than atomic lines, which make them ideal, complementary tool for studying cool stellar atmospheres as well as the internal structure of sunspots. Equivalent width for an adequate number of well identified molecular lines of these bands using the Gaussian-profile approximation method versus rotational quantum number J has been used to determine the effective rotational temperature of the CrH molecule. The range of effective rotational temperature value obtained from these bands is 1766 K to 2442 K. This range agrees well with the effective rotational temperatures derived for other molecules in sunspot umbrae.

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“…The electronic spectrum of diatomic chromium hydride, CrH, was first observed over 60 years ago (Gaydon & Pearse 1937). It was the subject of only six published papers within the first 40 years of its observation (Gaydon & Pearse 1937;Kleman & Liljeqvist 1955;Kleman & Uhler 1959;O'Connor 1967O'Connor , 1969Smith 1973), but the 1980 spectroscopic detection of CrH in sunspots (Engvold et al 1980) and S-type stars ( Lindgren & Olofsson 1980) increased the astrophysical interest in the molecule.…”

Section: Introductionmentioning

confidence: 99%

“…It was the subject of only six published papers within the first 40 years of its observation (Gaydon & Pearse 1937;Kleman & Liljeqvist 1955;Kleman & Uhler 1959;O'Connor 1967O'Connor , 1969Smith 1973), but the 1980 spectroscopic detection of CrH in sunspots (Engvold et al 1980) and S-type stars ( Lindgren & Olofsson 1980) increased the astrophysical interest in the molecule. In 1999, CrH was observed in the spectra of brown dwarfs ( Kirkpatrick et al 1999a), substellar objects that are intermediate in size and temperature between the least massive stars and the most massive planets ( Basri 2000).…”

Section: Introductionmentioning

confidence: 99%

Radiative Lifetime of thev = 0, 1 Levels of the \documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \usepackage[OT2,OT1]{fontenc} \newcommand\cyr{ \renewcommand\rmdefault{wncyr} \renewcommand\sfdefault{wncyss} \renewcommand\encodingdefault{OT2} \normalfont \selectfont} \DeclareTextFontCommand{\textcyr}{\cyr}

Shin

Brugh

Morse

2005

ApJ

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The time-delayed resonant two-photon ionization method has been used to measure the radiative lifetimes of the v ¼ 0 and 1 levels of the A 6 AE þ state of CrH, yielding values of 0:939 AE 0:019 and 1:027 AE 0:066 s, respectively (1 error limits). These measured lifetimes are about 16%-45% longer than those obtained in recent ab initio calculations, a result that is important for modeling of the atmospheric concentration of CrH in the class of substellar objects known as brown dwarfs. Based on these results, it is suggested that the line strengths used to calculate the opacity function used by astronomers should be reduced by a factor of 0.799. In addition, line positions are reported for the 0-0 band of the A 6 AE þ X 6 AE þ system of the minor isotope 50 CrH, along with a least-squares fit of the lines to the standard matrix Hamiltonian.

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Band Spectrum of Chromium Hydride, CrH

Cited by 19 publications

References 1 publication

Chromium dihydride (CrH₂): theoretical evidence for a bent⁵B₂ground state

Chromium dihydride (CrH₂): theoretical evidence for a bent⁵B₂ground state

On the effective temperature of large sunspot umbra using CrH sextets electronic state molecular lines

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Band Spectrum of Chromium Hydride, CrH

Cited by 19 publications

References 1 publication

Chromium dihydride (CrH2): theoretical evidence for a bent5B2ground state

Chromium dihydride (CrH2): theoretical evidence for a bent5B2ground state

On the effective temperature of large sunspot umbra using CrH sextets electronic state molecular lines

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Chromium dihydride (CrH₂): theoretical evidence for a bent⁵B₂ground state

Chromium dihydride (CrH₂): theoretical evidence for a bent⁵B₂ground state