1. Fluorescence spectroscopy of jet- cooled phenylvinylacetylene in its ground and first excited states Speaker: Ching-Ping Liu Coworkers: Josh Newby and Christian Müller Advisor: Dr. Timothy Zwier Department of Chemistry, Purdue University

2. Motivation (1)Completing a series: (2) Structural isomerization: (3) C 10 H 8 isomers: Alternatives to naphthalene in combustion, planetary atmospheres? Previous detection: C 4 H 2 * + styrene, no spectral analysis 1-phenyl-1,3-butadiene Sharp UV spectrum phenylvinylacetylenephenyldiacetylene Broad UV spectrum Z-form E-form

3. Experiment Laser beam Collection mirrors Collimating lens To optics Housing Supersonic expansion Fluorescence excitationDispersed fluorescence PMT Monochromator / CCD

4. Fluorescence excitation spectrum of PVA

5. Single vibrational level dispersed fluorescence spectrum with the excitation of the origin band. Torsional progression C s symmetry a (in plane) modes: 1 - 33 a  (out of plane) modes: 34 - 48  48 Obs / cm -1 89 186 1   2 3 4 5 6

6. 266 222 254 326 334 400 Excite 222 cm -1 Excite 254 cm -1 Excite 266 cm -1 Excite 326 cm -1 Excite 334 cm -1 Excite 400 cm -1 Part of the FE spectra SVLF spectra

7. FE spectra with various backing pressure of the carrier gases. (a) He 15 psi, and (b) He 40 psi, and (c) He 80 psi. (a) (b) (c) Clusters Cold band Hot bands v  =0 v  =1 v=0 v=1 v=2 v=3 S1S1 S0S0 -21 24 84 158 232 104 131

8. - 21 cm -1 + 24 cm -1 + 84 cm -1 + 158 cm -1 + 232 cm -1 Single vibrational level dispersed fluorescence spectra of hot bands. From v 47  =1 From v 48  =1 Duschinsky mixing

9. + 191 cm -1 + 254 cm -1 + 266 cm -1 + 400 cm -1 SVLF spectra with excitation involving the out-of-plane modes.

10. + 104 cm -1 + 222 cm -1 + 334 cm -1 + 539 cm -1 SVLF spectra with excitation involving the in-plane modes.

11. + 931 cm -1 + 948 cm -1 + 1214 cm -1 + 788 cm -1 + 810 cm -1 + 815 cm -1 + 1279 cm -1 + 726 cm -1 Single vibrational level dispersed fluorescence spectra.

12. Molecule S0S0 S1S1 S0S0 S1S1 S0S0 S1S1 S0S0 S1S1 S0S0 S1S1 Styrene624528776746999948101195912041209 trans-  -methylstyrene 6215378217951003927103595912081210 Phenylvinylacetylene6235398518151013931104894812181214 Alkylbenzene--- 526  4 --- 748  18 --- 932  2 --- 966  6 --- Table. Comparison of the vibrational frequencies of the benzene-type modes. R R R (6b) R (1) (12) (18a) (13) R R: substituent

13. Fluorescence excitation spectrum of phenylvinlyacetylene Warm condition Hot bands

14. 1C-R2PI and hole-burning spectra Conformer or isomer A Conformer or isomer B Hole-burn Probe S0S0 S1S1 S0S0 S1S1 R2PI UVHB

15. + 260 cm -1 band 89 186 34 74 ? The SVLF spectrum with the excitation in the unknown band. Benzene-type modes

16. Conclusion The analysis and assignments of the ground and first excited states of phenylvinylacetylene are reported. The spectroscopy reveals Duschinsky mixing with four lower- frequency out-of-plane modes and IVR at high excess energy. The unknown band at 260 cm -1 above the origin in FE spectrum is probably originated from the Z isomer. Future work 1.Quantitatively analyze Duschinsky mixing with four low- frequency out-of-plane modes. 2.Synthesize the Z isomer to get the spectral information for comparison with the E isomer. 3.UV-induced structural isomerization of E- or Z-PVA.

17. Acknowledgement Advisor: Dr. Timothy Zwier Group members: Dr. Christian Müller* Dr. Jasper Clarkson Esteban Baquero Alvin Shubert Nathan Pillsbury Tracy LeGreve Josh Newby* Chirantha Rodrigo Josh Sebree Dr. Daniel Lee Funding: Taiwan Merit scholarship