1. Infrared spectroscopy of two isomers of the OCS-CS 2 complex J. Norooz Oliaee, M. Dehghany, Mahin Afshari, N. Moazzen-Ahmadi Department of Physics and Astronomy, University of Calgary A. R. W. McKellar Steacie Institute for Molecular Sciences, National Research Council of Canada

2. Outline Previous work on OCS-CS 2 Our recent work on OCS-CS 2 Comparison with similar species OCS-CO 2 CO 2 -CS 2 Summary 2/11

3. FTMW Observation OCS-CS 2 dimer: Previous Work ORIENT Semi-Empirical Modeling ORIENT Semi-Empirical Modeling 3/11

4. OCS-CS2 dimer: Our recent work Infrared observation of the lowest-energy isomer of OCS-CS 2 at ~ 2057.91 cm -1 Structure I C s symmetry Planar a- and b-type @ ~ 2057.91 cm -1 Blank regions indicate OCS absorption lines. 4/11

5. Infrared observation of the intermediate-energy isomer of OCS-CS 2 at ~ 2060.07 cm -1 Blank regions indicate OCS absorption lines. Structure II C s symmetry Non-planar Predominantly c-type @ ~2060.07 cm -1 OCS-CS2 dimer: Our recent work Side view Top view 5/11

6. a c b Structure of the intermediate-energy isomer of OCS-CS 2 Structure II C s symmetry Non-planar Predominantly c-type @ ~2060.07 cm -1  R CM Rotational and Structural Parameters Comparison Table A/MHzB/MHzC/MHzR CM /Å  / ° Dihedral/ ° Peebles’ Group* 213810298983.49084.890.0 Our Group 2187.7(4.5)997.8(1.8)864.13(33)3.5578(17)74.89(46)Crossed * Semi-empirical modelling by ORIENT program OCS-CS2 dimer: Our recent work 6/11

7. Comparison with similar species: OCS-CO 2 dimer: previous studies FTMW observation of the planar S-interior slipped near-parallel OCS-CO 2 dimer ab initio calculations for O-interior slipped near-parallel OCS-CO 2 dimer 7/11

8. Comparison with similar species: OCS-CO 2 dimer: Our recent studies Isomer a structural parameters R CM /Å  1 / °  2 / ° Novick et al * 3.552(3)68.94(30)78.93(57) Our Group 3.5545(10)69.7(4)78.7(3) Isomer b structural parameters R CM /Å  1 / °  2 / ° Valdes et al † 3.913122.45131.05 Our Group 3.9862(10)118.0(5)135.8(3) * FTMW observation † ab initio calculations at the MP2/cc-pVTZ level @ 2066.1 cm -1 @ 2055.7 cm -1 8/11

9. Comparison with similar species: CO 2 -CS 2 dimer: previous studies Cross-shaped @ ~ 2346.55 cm -1 with R CM =3.392 (Å) 9/11

10. Lowest-energy isomer Intermediate- energy isomer Highest-energy isomer OCS-CS 2 OCS-CO 2 CO 2 -CS 2 Summary  MW 1  IR   MW 2  IR 3  MW 4  IR 1 Josh J. Newby et al, Phys. Chem. Chem. Phys. 7, 487-492 (2005) 2 Stewart E. Novick et al, J. Chem. Phys. 88, 687 (1988) 3 M. Dehghany et al, J. Chem. Phys. 130, 224310 (2009) 4 C. C. Dutton et al, J. Phys. Chem. A 102, 6904-6909 (1998) 10/11

11. Thanks for your attention!

12. Structural parameters for OCS-CS2 Structure I* R CM /Å  / °  / ° Inertial fit 3.8017(2)79.4(4)105.3(2) Ab initio 3.84173.6112.7 ORIENT 3.70676.2106.8 * Josh J. Newby et al, Phys. Chem. Chem. Phys. 7, 487-492 (2005)

13. Structural parameters for OCS-CS2 Structure I ParameterStructure I Structure IIStructure IIIAb initioExperimental Relative energy/ cm -1 06576-- A/MHz 24582138335423222369.6942(9) B/MHz 102710298011036994.4467(6) C/MHz 725898647716700.5137(3) * Josh J. Newby et al, Phys. Chem. Chem. Phys. 7, 487-492 (2005)