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

Observed Bands

Observed Transitions of WO

New Group

New States

Group 1 Group 2 Group 3

1Σ+

5Π

A'2

[7.5]0+ - X0+, 0-0

D1-X0+, 0-0

C2-X1, 0-1

D1-X0+, 1-1 [186WO-184WO = -0.07 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 ?

[a+15.3]0+ - [a+5.1]0+, 0-0

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+

Constants for Group 1

Constants for Group 2

Constants for Group 3

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

Ab Initio Results

Ab Initio Results

11000

6000

4900

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.

Acknowledgments

NASA Laboratory Astrophysics Program

UK Engineering and Physical Sciences Research

Council (EPSRC)