SPECTROSCOPIC OBSERVATION OF CS 2 DIMER Mojtaba Rezaei

SPECTROSCOPIC OBSERVATION OF CS 2 DIMER Mojtaba Rezaei, J. Norooz Oliaee, N. Moazzen-Ahmadi Department of Physics and Astronomy, University of Calgary, A. R. W. Mc. Kellar Steacie Institute for Molecular Sciences, National Research Council of Canada

Outline Unusual Structure of CS 2 Containing Dimers CS 2 Dimer Vibrational Modes Observed analyzed bands Summary

Unusual Structure of CS 2 Containing Dimers Most of the linear triatomic molecules form Planar dimers (CO 2)2 (N 2 O)2 (OCS)2 OCS-CO 2 OCS-N 2 O CS 2 molecule is capable of forming dimers with 3 D Structures Dutton et al (1998) Newby et al (2005) Present Work Planar Structure CO 2 -CS 2 Cross-shaped OCS-CS 2 (CS 2)2 I II III D 2 d symmetry Planar Crossshaped Planar Cross-shaped

CS 2 Dimerand Vibrational Observed Analyzed. Modes Bands 4 intramolecular vibrations Symmetric In Phase (A 1) Out of Phase(B 2) CS 2 monomer ν 1 fundamental region (~660 cm-1) Asymmetric vd. W Stretching Torsional Bending Motion Doubly Degenerate (E) Symmetry A 1 Symmetry B 2 Symmetry E ν 3 fundamental (~1535 cm-1) Fundamental band 1534. 1348 cm -1 Red shifted by 1. 221 cm-1 4 intermolecular vibrations Combination band 1545. 09 cm -1

Observed and Analyzed Bands q Perpendicular band (ΔK = ± 1) q Characteristic Intensity alternation (isotopologue, (12 C 32 S)2) Level spin statistical weight K" = odd 0 K" = 0 , J" = odd 0 All other levels 1 q 111 lines were assigned for fundamental band q 64 lines were assigned for combination band (with the same lower state parameters)

Molecular Parameters Ground state 0 / cm-1 Fundamental band Combination band 1534. 13480(8) 1545. 0909(1) A /MHz 1661. 22(13) 1656. 07(14) 1656. 203(86) B /MHz 802. 72(13) 801. 88(14) 798. 276(88) DJ /k. Hz 3. 82(31) 3. 89(39) 3. 12(41) DK /k. Hz 0. 0 1. 35(53) 0. 0 q+ / MHz -12. 445(40) -10. 770(65) q- / MHz -13. 610(38) -9. 43(12) 0. 037802(94)

Observed and simulated spectra Part of the P-branch of fundamental band (rms = 2. 7 10 -4 cm-1) Part of the R-branch of combination band (rms = 1. 88 10 -4 cm-1) q Effective rotational temperature: 2. 5 K q Gaussian line width: 0. 002 cm-1 The simulation and fit were done using Colin Western’s PGOPHER software.

OCS-CS 2 (CS 2)2 Torsional frequency 10. 96 cm-1 CO 2 -CS 2 Torsional frequency 15. 29 cm-1

Summary We studied We observed analyzed We found CS 2 dimer Two IR bands in the region of the CS 2 ν 3 fundamental q Cross-shaped structure q D 2 d symmetry q Intermolecular distance: 3. 539(7) Å q Torsional frequency : 10. 96 cm-1

Acknowledgments q Dr. Nasser Moazzen-Ahmadi q Dr. A. Robert W. Mc. Kellar Steacie Institute for Molecular Sciences National Research Council, Canada q Jalal Norooz Oliaee Thank you for your attention.