1. HIGH RESOLUTION INFRARED SPECTROSCOPY OF N 2 O-C 4 H 2 AND CS 2 −C 2 D 2 DIMERS MAHDI YOUSEFI S. SHEYBANI-DELOUI JALAL NOROOZ OLIAEE BOB MCKELLAR NASSER MOAZZEN-AHMADI

2. Previous studies Spectrometer N 2 O-C 4 H 2 CS 2 -C 2 D 2 (CS 2 ) 2 -C 2 D 2 Summary OUTLINE

3. MOTIVATION Theoretical Structure J. Norooz Oliaee,, Mahin Afshari, M. Dehghany, N. Moazzen-Ahmadi, A.R.W. McKellar, Journal of Molecular Spectroscopy 257 (2009) 133–136. Experimental structure a/b-type band Near parallel structure with C s symmetry M. Dehghany, M. Afshari, J. Norooz Oliaee, N. Moazzen-Ahmadi, and A.R.W. McKellar, Chem. Phys. Lett. 473, 26 (2009). FB09 1 2 1 2

4. Quantum cascade laser (N 2 O-C 4 H 2 ) or optical parametric oscillator (CS 2 -C 2 D 2 ) Rapid scan signal averaging with background subtraction (jet on minus jet off) Multi pass cell gives >100 traversals of laser through jet Wavelength calibration using reference gas and etalon Pulsed supersonic jet expansion Dual slit pulsed nozzle Repetition rate: 0.5 to 2 Hz Backing pressures ~5-20 atm Diffusion pump (Varian VHS-10) Backing pump (Edwards EM275) SPECTROMETER

5. EXPERIMENTAL SETUP

6.  Blue shifted 2.29 cm -1 w.r.t. N 2 O ν 1  Rotational temperature of 2.8 K  Line-widths of 0.0025 cm -1  C s symmetry a/b-type band  PGOPHER program is used N 2 O-C 4 H 2 : OBSERVED SPECTRUM

7. N 2 O-C 4 H 2 : MOLECULAR PARAMETERS ab-initio Calculation (DFT) ab-initio calculation( MP2) Experimental Value A ʺ /MHz 4622.3 4470.84496.60(17) B ʺ /MHz 1389.5 1494.51409.003(70) C ʺ /MHz 1068.4 1120.11070.731(50) - - - 0.0096 Experimental Value A ʹ /MHz 4478.14(14) B ʹ /MHz 1409.359(81) C ʹ /MHz 1069.769(52) 2226.051(1) Ground State Excited State

8. A ʺ /MHz 4136.96(22) B ʺ /MHz 1358.554(73) C ʺ /MHz 1020.539(57) A ʹ /MHz 4118.62(17) B ʹ /MHz 1358.691(83) C ʹ /MHz 1019.390(56) 2226.072(1) N 2 O-C 4 D 2 : OBSERVED SPECTRUM  Blue shifted 2.31 cm -1 w.r.t. N 2 O ν 1

9. N 2 O-C 4 H 2 STRUCTURE DFTMP2Experiment R(8,4)/Å3.593.693.593(3)  (8,4,5)/° 117109117 (3)  (9,8,4)/° 11697116 (12) 5: C atom 4: C 4 H 2 center of mass 8: N 2 O center of mass 9: O atom 5 4 8 9

10. OBSERVATION OF CS 2 -C 2 D 2 COMPLEXES

11.  (1988). D. Prichard et al. vibration-rotation spectrum  (1989). J. Muenter et al. microwave analysis study  (1989). Z. Huang et al. near-infrared experimental study CS 2 -C 2 D 2 : SIMILAR STRUCTURES b-type band Symmetric structure with C 2v symmetry Theoretical Structure Experimental structure

12. Blue shifted 1.75 cm -1 w.r.t. C 2 D 2 ν 3 Rotational temperature of 3 K Line-widths of 0.003 cm -1 C 2v symmetry b-type band CS 2 -C 2 D 2 : OBSERVED SPECTRUM

13. CS 2 -C 2 D 2 : MOLECULAR PARAMETERS Ground State Excited State Ground state ab-initio Calculation (DFT) ab-initio calculation ( MP2) Experimental Value A ʺ /MHz 2924.89 2872.592921.72(47) B ʺ /MHz 1841.10 2081.381823.86 (44) C ʺ /MHz 1129.88 1206.901119.93(38) - - - 0.0071 Excited stateExperimental Value A ʹ /MHz 2921.38(41) B ʹ /MHz 1823.17(45) C ʹ /MHz 1120.11(39) 2438.165(1)

14. (DFT)Experiment R(2,6) /Å3.663.6702(74) (DFT) R(3,7) /Å5.02 2 6 7 2 3 CS 2 -C 2 D 2 : STRUCTURE

15. . Blue shifted 0.32 respect to C 2 D 2 ν 3 Rotational temperature of 3 K Line-widths of 0.003 cm -1 C 2 symmetry a/b-type band (CS 2 ) 2 -C 2 D 2 : OBSERVED SPECTRUM

16. (CS 2 ) 2 -C 2 D 2 TRIMER Ground state ab-initio calculation (DFT) Experimental Value A ʺ /MHz 1035.421025.41(15) B ʺ /MHz 553.09553.35 (19) C ʺ /MHz 545.32552.76(20) Excited stateExperimental Value A ʹ /MHz 1025.7938(18) B ʹ /MHz 552.87(22) C ʹ /MHz 552.32(20) 2436.736(1) Ground State Excited State

17. (CS 2 ) 2 -C 2 D 2 : OPTIMIZED STRUCTURE Ab-initio calculation R(3,6) /Å3.09 R(6,8) /Å2.01  (6, 8, 9)/˚ 110.1 Γ (9,8,10,11)/˚ 25 Γ (8,6,3,4)/˚ 80.9 3 6 8 10 11 9 4 3:C 2 H 2 center of mass 6:(CS 2 ) 2 center of mass 8:#1 CS 2 center of mass 10:#2 CS 2 center of mass c a b

18. SUMMARY AND CONCLUSION: N 2 O-C 4 H 2, CS 2 -C 2 D 2 and (CS 2 ) 2 -C 2 D 2 experimental and theoretical IR spectroscopy We studied A (blue shifted ) band in the region of N 2 O ν 1 + Two bands (blue shifted ) in the region of the C 2 D 2 ν 3 We observed and analyzed  N 2 O-C 4 H 2 near parallel structure with C s symmetry  CS 2 –C 2 D 2 planar structure with C 2V symmetry  (CS 2 ) 2 -C 2 D 2 with C 2 symmetry We found

19. Thank You

20.  M. Rezaei, J. Norooz Oliaee, N. Moazzen- Ahmadi, A.R.W. McKellar, J. Chem. Phys. 134,144306, (2011).  M. Rezaei, J. Norooz Oliaee, N. Moazzen- Ahmadi, A.R.W. McKellar, Chem. Phys. 13, 12635, (2011). Should I mention ocs-c2h2!!! trimer

21. N2O–C2H2 Planar, near-parallel (O-in), Cs 3.296 h1 = 93.9 [113] h2 = 99.7

22. AB-INITIO CALCULATION ON CS 2 -C 2 D 2 DIMER Minimum energy structures saddle point structures Ab initio calculations @MP2 level ???

24. DAQ Trigger Jet Signal IR Detectors Etalon QCL PZT Driver Ref. Gas Frequency Locking Box Supersonic Expansion Nozzles Multipass Cell DAQ Card Counter 1 Counter 3 Counter 4 Counter 2 Timer Card Boxcar Averager Diffusion Pump Mixture Jet Triggers Valve Controller Gas Supply Laser Controller Function Generator