INFRARED SPECTROSCOPY OF C 6 D 6 Rg n (n = 1, 2)

Transcription

1 INFRARED SPECTROSCOPY OF C 6 D 6 Rg n (n = 1, 2) J George, M Yousefi, M Razaei, B McKellar, N M Ahmadi University of Calgary June 19, 2014

2 OUTLINE BACKGROUND Prior Investigations on Benzene-Noble gas complexes EXPERIMENT Spectrum Observation RESULTS Derived Molecular Parameters Observed Vibrational Shifts CONCLUSION

3 PRIOR INVESTIGATIONS ON BENZENE-NOBLE GAS COMPLEXES 1978: C 6 H 6 He 1,2 Electronic Spectra (S.M.Beck et al.) 1990: C 6 H 6 Ar, C 6 D 6 Ar Microwave Spectra (Th. Brupbacher et al.) 1991: C 6 H 6 20,22 Ne Microwave Spectra (Th. Weber et al.) 1992: C 6 H 6 X(X = Ne, Ar, Kr, Xe, N 2 ) Electronic Spectra (H.J.Neusser et al.) 1993: Ne C 6 H 6 H 2 O Microwave (E.Arunan et.al) 1993: C 6 H 6 X(X = 20 Ne, 129 Xe, 132 Xe), Microwave (Th. Brupbacher et al.) 2013: C 6 H 6 He 1,2 Electronic Spectra (M.Hayashi et al.)

4 EQUILIBRIUM STRUCTURE 1 OF BENZENE-Rg AND BENZENE-(Rg) 2 1 H.J. Neusser, R. Sussman, in Jet Spectroscopy and Molecular Dynamics, eds. J.M. Hollas, D. Phillips, Springer Media, New York (1995) 118

5 PRESENT WORK Observation of Benzene-(Rg) n (n = 1, 2) in the infrared region, where rare gas being He, Ne, Ar ν 12 C-D stretching band of C 6 D 6 near 2289 cm 1 ν 12 fundamental band is in strong fermi resonance with ν 2 + ν 13 combination band 1 near 2275cm 1 Laser wavelength region 2173 cm 1 to 2564 cm 1 The spectra were observed at a resolution of 60 MHz 250 MHz- C6 H 6 He 1,2, 2013, (M.Hayashi et al.) GHz- C 6 H 6 He 1,2, 1978, (S.M.Beck et al.) 3 1 M. Rezaei, A.R.W. McKellar, N. Moazzen-Ahmadi, J. Mol. Spec. 296 (2014) 14 2 M. Hayashi, Y. Ohshima, Chem. Phys. 419 (2013) S.M. Beck, M.G. Liverman, D.L. Monts, R.E. Smalley, J. Chem. Phys. 70 (1979) 232

6 LASER SPECIFICATION Lockheed Martin Aculight Argos Optical Parametric Oscillator source Idler wavelength range: 3.9 to 4.6 microns Linewidth <1MHz Power output >50 all wavelengths

7 SPECTROMETER Direct IR absorption spectroscopy Optical Parametric Oscillator Reference and etalon for wavelength calibration Pulsed supersonic jet expansion Slit or pinhole nozzle (General Valve) Repetition rate: 0.5 to 2 Hz Backing pressures 5-20 atm 10inch diffusion pump (Varian VHS-10) Backing pump (Edwards EM275) Cooled nozzle (down to -75 C)

8 EXPERIMENTAL SETUP

9 C 6 D 6 He 1,2 Gas mixture - 0.1% C 6 D 6 with carrier gas as Helium Backing pressure about 13 atm Nozzle temperature -50 o C and -75 o C, Rotational temperature: 2.5K to 1.5K

10 C 6 D 6 Ne 1,2 Gas mixture - 0.1% C 6 D 6, 2%Ne with carrier gas as Helium Nozzle temperature -40 o C, Rotational temperature: 2.5K to 1.5K

11 C 6 D 6 Ar 1,2 Gas mixture - 0.1% C 6 D 6, 2%Ar with carrier gas as Helium

12 COMPARING ROOM TEMPERATURE AND VALVE COOLED SPECTRA OF BENZENE-HELIUM

13 MOLECULAR STRUCTURE AND SYMMETRY Symmetric top Benzene-Rg with a C6v Benzene-(Rg)2 with a D 6h

14 MOLECULAR PARAMETERS FOR C 6 D 6 AND Rg C 6 D 6 COMPLEXES C 6 D 6 He C 6 D 6 Ne C 6 D 6 Ar C 6 D 6 B (23) (17) C (A ) ν (1) (2) (2) (1) B (68) (22) (17) (28) C /A (50) (18) (18) (78) ζ (39) (36) (11) ν (2) (2) (2) (1) B (48) (31) (17) (23) C /A (37) (26) (16) (76) ζ (33) (29) (10) 1 T. Brupbacher, A. Bauder, Chem. Phys. Lett. 173 (1990) J. Plva, A. Valentin, J. Chazelas, L. Henry, J. Mol. Spectrosc. 134 (1989) 220

15 MOLECULAR PARAMETERS FOR C 6 D 6 AND Rg 2 C 6 D 6 COMPLEXES C 6 D 1 6 He 2 C 6 D 6 Ne 2 C 6 D 6 Ar 2 C 6 D 6 B (25) (3) (16) C (A ) ν (1) (16) (18) (17) B (68) (25) (37) (1) C /A (50) (4) (2) (2) ζ (45) (48) (3) ν (2) (1) (18) (1) B (48) (23) (3) (1) C /A (37) (14) (2) (18) ζ (4) (4) (38) 1 M. Rezaei, A.R.W. McKellar, N. Moazzen-Ahmadi, J. Mol. Spectrosc. 296 (2014) 14

16 VIBRATIONAL SHIFTS Table: Vibrational shift w.r.t C 6 D 6 vibration in cm -1 shift ν 12 shift ν 2 + ν 13 Rg C 6 D 6 Rg 2 C 6 D 6 Rg C 6 D 6 Rg 2 C 6 D 6 He Ne Ar

17 EFFECTIVE INTERMOLECULAR DISTANCES Table: Intermolecular distances in Å C 6 H 6 C 6 D 6 Rg Rg 2 Rg Rg 2 He 3.602(9) 3.596(6) 3.593(1) 3.601(1) Ne (1) 3.438(17) Ar (17)

18 CONCLUSION Infrared observation of C 6 D 6 Rg n (n = 1, 2) were done with very high resolution (60 MHz) Molecular parameters and intermolecular distances were calculated Future Prospective Further increase the backing pressure and cooling of the nozzle Expecting to observe higher clusters with more number of Helium atoms

19 THANK YOU