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FOURIER TRANSFORM EMISSION FOURIER TRANSFORM EMISSION SPECTROSCOPY AND SPECTROSCOPY AND AB INITIOAB INITIO
CALCULATIONS ON WOCALCULATIONS ON WO
R. S. Ram, Department of Chemistry, R. S. Ram, Department of Chemistry, University of ArizonaUniversity of Arizona
J. LiJ. Liéévin, Université Libre de Bruxelles,vin, Université Libre de Bruxelles,Laboratoire de Chimie Physique Laboratoire de Chimie Physique
MolMolééculaireculaireP. F. Bernath, Department of Chemistry, P. F. Bernath, Department of Chemistry,
University of YorkUniversity of York
Transition Metal Containing Molecules
The study of transition metal containing molecules provide insight into chemical bonding in simple metal systems. The study of these molecules are also of theoretical importance. Experimental data are needed to test and advance the quality of ab initio calculations. The transition metal containing molecules are also of astrophysical importance.
The unpaired d-electrons produce a large number of low-lying electronic states with high spin and large orbital angular momentum. In addition the large spin-orbital interactions result in complex spectra making their analysis difficult.
WO is a good example.
Previous WorkWeltner & McLeod (1965)Green & Irvin (1981)
Vittalachar & Krishnamurthy (1954)Gatterer et al. (1957)Samoilova et al. (1981)Kuzyakov et al. (1997)
Kraus et al. (1998)Lorenz et al. (1999)
Nelin & Bauschlicher (1985)
Ram et al. (2001) [3Σ- ground state]
Cooke et al. (2004) [3Σ- ground state]
Matrix Isolation
Emission and Absorption
Laser Spectroscopy
SCF and CASSCF Calculations
FT Emission Spectroscopy
Microwave Spectroscopy
Present Work WO spectra re-investigated in the 4000-25000 cm-1 region
Ab Initio calculations performed for states below 35000 cm-1
• Microwave discharge of WCl6 vapor mixed with 1.9 Torr of He
• Fourier transform spectrometer of the National Solar Observatory
at Kitt Peak
UV beam splitter UV beam splitter
InSb detectors Super blue Si
Green glass filters Filters: OG530 and CuSO4
Resolution: 0.025 cm-1 Resolution: 0.03 cm-1
104 scans (10 hrs) 6 scans each (one hour)
9000-19000, 17000-35000 cm-14000-10000 cm-1
C1-X0+, 0-0Large isotope splittingeven in the 0-0 bands
[186WO-184WO = -0.26 cm-1]
Strong isotope dependant interaction in the excited state ?
State v Tv Bv 107 × Dv 104 × qv
2 a+2111.7994(29) 0.4121963(52) 2.492(31) 1.62*
1 a+1059.9311(10) 0.4142214(90) 2.489(25) 1.6207(36)
X1 0 a 0.4162403(89) 2.485(24) 1.6258(55)
4 4181.9326(31) 0.4074388(72) 2.638(22) --
3 3148.5457(20) 0.4094780(65) 2.641(20) --
2 2107.0887(15) 0.4114974(56) 2.591(16) --
1 1057.56545(86) 0.4135235(53) 2.573(14) --
X0+ 0 0.0 0.4155377(54) 2.557(15) --
Constants for the X3Σ- state
q = (γ-2B)2/(2λ+γ-2B)
λ = ~207 cm-1~414 cm-1
X1
X0+
Const. (cm-1) X0+ X1
ωe 1065.5951(71) 1067.9939(34)
ωexe 4.0103(40) 4.0314(16)
ωeye -0.00268(60) --
Be 0.4165548(60) 0.4172526(31)
αe 0.0020237(23) 0.002022(15)
re(Å) 1.658351(12) 1.6569637(62)
Equilibrium constants for the X3Σ- state
Summary
Emission spectrum of WO has been investigated in the 4000-25000 cm-1 region and observed bands have been classified into three groups.
First two groups have lower states with Ω=0+ and Ω=1 which have been assigned as the spin components of the X3Σ+ ground state of WO.
Third group consists of seven bands with a band at 9877 cm-1 having its upper state common with the A´2 state of group 2. Some of the lower states of this group are probably the spin components of the predicted 15Π state.
The observed 1Σ+ state at 4910 cm-1 is probably the predicted 11Σ+ state.