1. INFRARED AND ULTRAVIOLET SPECTROSCOPY OF JET-COOLED 2-BENZYLPHENOL: I STRUCTURE AND LARGE-AMPLITUDE TORSIONAL MOTION CHIRANTHA P. RODRIGO, CHRISTIAN W. MÜLLER, TIMOTHY S. ZWIER Department of Chemistry, Purdue University West Lafayette, IN 47907-2084 International Symposium of Molecular Spectroscopy 62 nd Meeting June 18-22, 2007

2. Outline Introduction Introduction Experimental Setup(s) Experimental Setup(s) Supersonic Jet Expansion Supersonic Jet Expansion FES (Fluorescence Excitation Spectra) FES (Fluorescence Excitation Spectra) HOLEBURNING (UV-UV ) HOLEBURNING (UV-UV ) SVLF (Single Vibronic Level Fluorescence) SVLF (Single Vibronic Level Fluorescence) FDIRS S 0 and S 1 (Fluorescence Dip Infrared Spectroscopy) FDIRS S 0 and S 1 (Fluorescence Dip Infrared Spectroscopy) High-Resolution UV Spectra High-Resolution UV Spectra Calculations Calculations Results Results Summary Summary

3. Introduction 2-benzylphenol (or Hydroxydiphenylmethane) One of the series of diphenylmethane type molecules diphenylmethane (DPM) diphenylmethane (DPM) § 2-benzylphenol (2BP) hydroxydiphenylmethane bis (2-hydroxydiphenyl)methane (2HDPM) bis (2-hydroxydiphenyl)methane (2HDPM) † § Stearns, J.A., Zwier T.S. et al (in preparation) † Pillsbury N.R., Zwier T.S. et al (in preparation) A B A B A B

4. Experimental Sample Preparation: 98% Purity, Alfa Aesar ® Melting point 51°C Supersonic Jet Expansion: Pulsed valve operating at 20Hz Carrier gas (He) pressure, 2-5 bar Nozzle orifice (800μm) Temperature behind the nozzle 70°C

5. UV-UV Holeburning Spectroscopy Fluorescence Excitation Spectrum UV-UV Holeburning Spectrum Records UV spectra of individual isomers free from interference from one another S 1 ← S 0 Origin band found at 36142 cm  1 Phenol origin* band at 36348 cm  1, Cresol at 36421 cm  1 Single conformational isomer for 2bp *Fujimaki, E.,Fujii, A., Ebata, T., and Mikami N.; J. Chem. Phys. 2000, 112,137

6. Single Conformation IR Spectroscopy – S 0 (FDIR) *Fujimaki, E.,Fujii, A., Ebata, T., and Mikami N.; J. Chem. Phys. 2000, 112,137 Records ground state IR spectra *

7. S 0 FDIR spectroscopy *Fujimaki, E.,Fujii, A., Ebata, T., and Mikami N.; J. Chem. Phys. 2000, 112,137 Records ground state IR spectra B3LYP/6- 31G*

8. S 1 FDIR Spectrum S 0 and S 1 FDIR Spectra of 2bp *Fujimaki, E.,Fujii, A., Ebata, T., and Mikami N.; J. Chem. Phys. 2000, 112,137 OH frequency of exited state phenol @ 3581 cm  1

9. Excited State Vibrational Modes - 29 cm  1 band progression - 41 cm  1 band progression

10. Calculation Results 29 cm  1 41 cm  1 Mode Exp. Freq. (cm -1 ) CIS/6-31G* Unscaled0.90 scaled 1 29 34.230.8 2 41 4641.4 3 53 5549.5 4 - 123110.7 5 - 215193 0 1 1 0 2 1

11. Comparison Between FE and SVLF Mode Exp. Freq. (cm -1 ) B3LYP/6-31G* Unscaled0.97 scaled 1 30 36.735.6 2 45 50.649 3 63 67.661 4 - 5 - OH Stretch 3584 36983584 Ground state calculations and results 29 45 41

12. Single Vibronic Level Fluorescence (SVLF) Origin band and +41 band SVLF has similar FC factors 41 cm  1

13. Single Vibronic Level Fluorescence (SVLF) Origin band and +41 band SVLF has similar FC factors Is it Duschinsky mixing ?

14. High Resolution UV Spectroscopy High Resolution Spectra (Rotational bands) Ground state rotational constants were obtained using Microwave data. (NIST) Excited state rotational structures of vibronic bands were taken using high resolution spectroscopy at NIST. Reasonable fittings for High resolution data were obtained with jb95 fitting program.

15. Summary Fluorescence Excitation spectrum and S 0, S 1 FDIR spectra recorded. Single conformation molecule Locked conformation due to the π  OH hydrogen bonding Is there a second excited state conformer ? Are the unusual FC factors due to Duschinsky mixing in the excited state ?

16. Acknowledgement Advisor, Prof. Timothy S. Zwier Zwier Research Group Dr. Christian W. M ü ller, Nathan Pillsbury, Bill James, Esteban Baquero, Josh Newby, Tracy LeGreve, Alvin Shubert, Dr. Ching Ping Liu, Dr. Jasper Clarkson, Josh Sebree Dr. Kevin Douglas (NIST) Collaborators Dr. David Plusquellic (NIST) Department of Chemistry, Purdue University Funding: Department of Energy

17. EXPERIMENTAL S1 FDIRS spectra at origin and +41 bands