VADIM L. STAKHURSKY Radiation Oncology, Duke University Clinic, DUMC 3295, Durham, NC 27710.

1. SIMULATION OF THE SPIN-VIBRONIC STRUCTURE IN THE GROUND ELECTRONIC STATE AND EMISSION SPECTRA INTENSITIES FOR CH3O RADICAL VADIM L. STAKHURSKY Radiation Oncology, Duke University Clinic, DUMC 3295, Durham, NC 27710. XIAOYONG LIU, VLADIMIR A. LOZOVSKY†, ILIAS SIOUTIS, C. BRADLEY MOORE*, and TERRY A. MILLER Laser Spectroscopy Facility, Department of Chemistry, The Ohio State University 120 W. 18th Avenue, Columbus OH 43210. †Deceased *Northwestern University, Evanston, IL, 60208-1108.

2. Motivation • 1. Jahn-Teller distortion can significantly affect the characteristics of the molecule, e. g. rotational and vibrational spectra, partition function, rate of chem. reaction, enthalpy • 2. Because of the relatively small size we use methoxy as a benchmark system for analysis of various effects of coupling of electronic and vibrational motion, e. g. Jahn-Teller effect, Herzberg-Teller effect, etc.. • 3. We develop a generic throughput application for fast data analysis of a wide variety of JT active systems.

3. Harmonic potential JT distorted potential

4. Vibrational frequencies of CH3O 1289 cm-1 2948a cm-1 662 cm-1 1362 cm-1 1047 cm-1 2840b cm-1 C-O stretch symmetric C-H stretch CH3 umbrella 930 cm-1 3078 cm-1 1403 cm-1 2774 cm-1 653 cm-1 1487 cm-1 asymmetric C-H stretch scissors CH3 rock aD. E. Powers, M. B. Pushkarsky and T. A. Miller, J. Chem. Phys. 106, 6863 (1997). bS. C. Foster, P. Misra, T.-Y. Lin, C. P. Damo, C. C. Carter, and T. A. Miller, J. Phys. Chem. 92, 5914 (1988).

5. E Pseudo Jahn-Teller A Optical transition PJT Hamiltonian E- E+ where coupling matrix elements can be calculated as and ladder operator Same effect can be described via Herzberg-Teller effect, that is when transitional dipole moment has dependency along vibrational coordinate: C.F. Jackels, J. Chem. Phys. 76, 505 (1982).

6. Spin-vibronic Hamiltonian e Standard: e+ e- Less frequently used terms: where

7. SOCJT as a tool for JT problem analysis • What is SOCJT? • Fortran code for multidimensional Jahn-Teller problem with/without spin-orbit interaction • SOCJT gives: • Positions of spin-vibronic levels of the molecule in degenerate electronic state • Insight into composition of the level in terms of harmonic oscillator quantum numbers |v, l> • providing a tool for levels “labeling” • Calculates UV spectrum for absorption or emission experiments • SOCJT input: • PES parameters up two third order: • Harmonic frequencies ωi and anharmonicities • Linear JT parameters, Di • Quadratic JT parameters, Ki, and cross-quadratic terms for interaction of degenerate vibrations • Bilinear terms for coupling of symmetric and degenerate modes • Fermi iteraction terms Q3 • Terms Q3 non-diagonal in the projection of the electronic orbital momentum • Spin-Orbit coupling parameter aze.

8. Establishing the PJT parameters, DF pumped via 35 PJT explains appearance of A1 and A2 levels of vibrations v6, v5 and v4.

9. Simulations of DF spectrum pumped via 3141 PJT explains appearance of origin and CO stretch progression in the spectrum

10. Establishing the PJT parameters, DF pumped via 3361 No significant difference

11. Establishing the PJT parameters, DF pumped via 3351 No significant difference

12. Determined constants and comparison with ab-initio Aso, ωi (i=1, 4-6) and b14 in cm-1 aT. A. Barckholtz and T. A. Miller, J. Phys. Chem. A 103, 2321 (1999). bU. Höper, P. Botschwina and H. Köppel, J. Chem. Phys. 112, 4132 (2000) and J. Schmidt-Klügmann, H. Köppel, S. Schmatz and P. Botschwina, Chem. Phys. Lett. 369, 21 (2003). cThis value was introduced phenomenologically to match the separation of the vibrationless spin-doublet in workb. dA. V. Marenich and J. E. Boggs, J. Chem. Phys. 122(2), 024308 (2005).

13. Conclusions and future work • We extended the SOCJT VIEW code to compute intensities of the vibronic • transitions with correction for pseudo Jahn-Teller effect. The coefficients for • coupling along different degenerate vibrational coordinates are extracted from • the experimental spectra. • 2. The PJT corrections to intensities are important in analysis of DF spectrum • excited through symmetric level 35, and through CH stretch • fundamental 3141, but insignificant for simulations of spectra excited through • 3351 and 3361. • 2. The PJT correction approach has to be applied to the analysis of the vibronic • Spectra of CHD2O (NEXT TALK). THANK YOU

14. ACKNOWLEDGMENTS Ohio State University

15. SOCJT GUI hybrid capabilities SOCJT code is interfaced to spectra simulation and visualization package SpecView • The features of the product: • Simulate vibronic structure in degenerate electronic state of a Cnv molecule with up to 7 • Jahn-Teller active vibrational modes and up to 5 non-active modes • Simulate intensities of vibrational features observed in dispersed fluorescence (DF) and • absorption spectra • Fast calculation of spectra (2-5 sec for region up to 3000 cm-1 in methoxy) • Ability to run non-linear least square fit of simulated lines to frequencies of observed features • (Levenberg-Marquardt method) • .