1. 6/19/12 1 DEEPALI N. MEHTA, POLINA NAVOTNAYA, ALEX PAROBEK, RACHEL CLAYTON, VANESA VAQUERO VARA AND TIMOTHY S. ZWIER 67 th International Symposium on Molecular Spectroscopy TG10 Department of Chemistry, Purdue University West Lafayette, IN 47907 VIBRONIC SPECTROSCOPY OF PHENYLVINYLNITRILE (E)-phenylvinylnitrile

2. Motivation 2 [1] Kemsley, J.,Chemical and Engineering News, 2007, 85, 11 [2] Raulin, F., Space Sci. Rev. 135, 2008, 37-48 Figure 1 1 : Schematic of reactions in Titan’s atmosphere. Titan is a model system for studies of primordial Earth 2 Titan’s chemistry occurs via ion and neutral pathways. 2

3. Motivation The formation of benzene (78 amu) has been investigated. 3 Compounds at 78 amu and greater, suggesting possibility benzene-based derivatives. 4 Species such as HCN, HC 3 N, C 2 N 2, and NH 3 open up possibility of nitrogen heteroaromatics. 5  tholins [3] Wilson, E. H., and Atreya, S. K., J. Geophys. Res.-Planet, 2004, 109 [4] J. H. Waite, D. T. Young, T. E. Cravens, A. J. Coates, F. J. Crary, B. Magee, J. Westlake, Science, 2007, 316, 870-875 [5] A. J. Trevitt, G. Boulay, C. A. Taatjes, D. L. Osborn, S. R. Leone, J. Phys. Chem. A, 2010, 114, 1749-1755 Figure 2 4 : Density as a function of mass, for compounds present in Titan’s atmosphere. 3

4. Motivation 4 (E)-phenylvinylnitrile (Z)-phenylvinylnitrile quinoline As an extension of previous Zwier group studies Structural isomers of naphthalene that may isomerize to form naphthalene upon photochemical excitation or discharge (E)-phenylvinylacetylene (Z)-phenylvinylacetylene naphthalene

5. Experimental 5 Laser Induced Fluorescence UV laser (tuned) (S 0,v=0) A * (S n ) Detect total fluorescence PMT UV laser (fixed) Total fluorescence CCD Dispersed Fluorescence Collisional cooling to zero- point vibrational levels Supersonic Expansion S0S0 Cooling

6. UV-UV Hole-burning Spectroscopy Δt = 50-200 ns Hole-burn Laser (10Hz) Probe Laser (20Hz) Spectra collected using active baseline subtraction Wavenumbers (cm -1 ) Probe only Difference * Probe + Hole-burn Lasers spatially overlapped but temporally separated 6

7. Predicted Geometry Change Upon Excitation 7 π π*π π* Ground StateExcited State Ground State: Density Functional Theory (DFT): B3LYP/6-311++G(d,p). Excited State: Time Dependent DFT (TDDFT): B3LYP/6-311++G(d,p). C(1) C(α)

8. Fluorescence Excitation Spectrum 8 Origin at 33,827cm -1 S 1 ( 1 A’)  S 0 ( 1 A’) Range= 33,500 – 35,850cm -1 000000

9. Hole-burning FES = top HB = bottom * 9

10. Origin Dispersed Fluorescence 10

11. In-Plane Fundamentals 11 0 0 0 + 106 cm -1 0 0 0 + 229 cm -1 0 0 0 + 343 cm -1 0 0 0 + 536 cm -1 27 1 0 27 1 1 29 1 0 29 1 1 30 1 0 30 1 1 31 1 0 31 1 1 FR

12. Duschinsky Mixing 12 Form of normal modes changes upon excitation. Modes in excited state can be represented as a linear combination of modes in the ground state. Christian W Müller, Josh J Newby, Ching-Ping Liu, Chirantha P Rodrigo, Timothy S Zwier, Physical Chemistry Chemical Physics, 2010, 12(10):2331-43.

13. Duschinsky Mixed Out-Of-Plane Modes 13 Christian W Müller, Josh J Newby, Ching-Ping Liu, Chirantha P Rodrigo, Timothy S Zwier, Physical Chemistry Chemical Physics, 2010, 12(10):2331-43. 45 44 43 42

14. Duschinsky Mixed Modes 14 0 0 0 + 246 cm -1 0 0 0 + 262 cm -1 0 0 0 + 317 cm -1 43 2 2 43 2 1 44 1 1 43 2 1 45 1 1 43 2 0 44 0 2 43 2 0 44 0 1 45 0 1 43 2 0 45 0 2 42 1 1 44 1 1 42 1 0 43 0 1 44 1 1 42 1 0 43 1 2 43 2 0 42 1 0 44 1 0 42 1 0 43 1 0 42 1 1 43 1 1

15. Hot Bands and Sequence Bands 15 + 22 cm -1 + 77 cm -1 + 152 cm -1 - 22 cm -1 000000

16. Hot Bands and Sequence Bands 16 0 0 0 – 22 cm -1 0 0 0 + 22 cm -1 X 1 0 Y 0 1 X11X11 v X’ -v Y’’ = + 22 cm -1 v X’ -v X’’ = - 22 cm -1 v X’’ -v Y’’ = + 44 cm -1 _ X1X1 Y1Y1 X1Y0X1Y0 S0S0 S1S1

17. 17 Intramolecular Vibrational Redistribution 0 0 0 + 804 cm -1 0 0 0 + 950 cm -1 0 0 0 + 966 cm -1 0 0 0 + 1149 cm -1 0 0 0 + 1155 cm -1 0 0 0 + 1216 cm -1 0 0 0 + 1287 cm -1

18. 18 (E)-PVN = top (E)-PVA = bottom Fluorescence Excitation Spectrum: (E)-PVN vs. (E)-PVA

19. Frequency Assignments and Modes of (E)-PVN 19 Table I. Experimental and calculated vibrational frequencies of phenylvinylnitrile (tentative assignments) Mode a Approximate description S 0 stateS 1 state Expt. c Calc. d Expt. c Calc. e a 17 Ring + substituent deformation1279129511551238 22 Ring + substituent deformation106310501045 25 Ring + substituent deformation886 or 837859822 27 645632569 29 386383343375 31 110109106109 aa 42 Ring deformation404409195386 43 245254121189 44 C(1)-C(a) bend93946799 45 C(1)-C(a) torsion4863 41 a Numbering according to Mulliken numbering scheme b Approximate description of normal mode in ground state. c Experimental frequency, measured from the origin. d Ground state frequency calculated with B3LYP/6-311++G(d,p) without scaling. e Excited state frequency calculated with TD-DFT: B3LYP/6-311++G(d,p) without scaling. 45 44 43 42

20. Summary and Conclusions 20 The electronic origin of (E)-PVN was found to occur at 33, 827 cm -1, which is ~230 cm -1 to the blue of (E)-PVA. Extensive Duschinsky mixing in low frequency out-of-plane modes. Mode-specific IVR

21. Future Directions 21 Ming-Fu Lin, Yuri A. Dyakov, Chien-Ming Tseng, Alexander M. Mebel, Sheng Hsien Lin, Yuan T. Lee,and Chi-Kung Ni The Journal of Chemical Physics, 2005, 123,054309 J. A. Sebree, et al., J. Am. Chem. Soc. 2012, 134, 1153. ? Perform further analysis and try to model/fit Duschinsky mixing. Characterize the electronic spectroscopy of (Z)-PVN Photochemistry of (Z)-PVN to test formation of quinoline 26 kcal/mol 96 kcal/mol 0 kcal/mol

22. Acknowledgements 22 Professor Timothy S. Zwier The Zwier Group Evan Buchanan (WF12,WG08) Zachary Davis (TF10) Jacob Dean (TF09,WG10) Joseph Gord (MF08) Nathan Kidwell (TG09,FB07) Joseph Korn Dr. Ryoji Kusaka (TD09) James Redwine Nicole Burke Dr. Vanesa Vaquero Vara (TD09) Patrick Walsh Di Zhang (FB08)