VIBRONIC ANALYSIS FOR TRANSITION OF ISOPROPOXY Rabi Chhantyal-Pun, Mourad Roudjane, Dmitry G. Melnik and Terry A. Miller TD03

Motivation : Oxidation of Hydrocarbons * J. J. Orlando, G. S. Tyndall, T. J. Wallington, Chem. Rev. 103, 4657 (2003)

Jahn Teller Effect Pseudo Jahn Teller Effect Pseudo Jahn Teller Effect 355(10) cm (7) cm -1 Ramond et. al. J. Chem. Phys. 112, 1158 (2000) Rabi Chhantyal-Pun, Jinjun Liu and Terry A. Miller, TI14, MSS 2012 Columbus Jin et. al. J. Chem. Phys. 121, (2004) CH 3 O C2H5OC2H5O i-C 3 H 7 O Foster et. al. J. Phys. Chem (1986) Motivation : Spectroscopy

XCH 2 CH 2 ONO / He General Valve ControllerDG535 Pulse Generator XeF Excimer Laser Nd:YAG Laser Sirah Dye Laser Nozzle T0T0 PMT Q-Switch Flash Lamp T 0 / GPIB T0T0 Lens Frequency Doubler XCH 2 CH 2 O NO Experiment : LIF Setup

1 J. Liu, D. Melnik and T. A. Miller, To be published CO stretch cm -1 Carter et. al. J. Phys. Chem. A (2000) x (b) z (c) y (a) -Cs plane (bc plane in the inset) contains central HCO atoms -TD-CAM-UB3LYP/6-31+G(d) Transition of Isopropoxy Method Excited State Rotational constants ABC UCIS/6-31+G(d) TD-UB3LYP/6-31+G(d) TD-CAM-UB3LYP/6-31+G(d) TD-UWB97X/6-31+G(d) Exp

a TD-CAM-UB3LYP/6-31+G(d) b Pseudo Jahn-Teller active modes ModeSymmetry DescriptionCalc. a Exp. 10 b HCO bend CC stretch CO stretch CCCO umbrella CCC bend In-phase CH 3 torsion b CO wag Out-of-phase CH 3 torsion d Band d is a hot band Transition of Isopropoxy

B̃ Ã X̃ ν 14 2ν 27 ν 13 2ν 15 ν 26 a’ a’’ a’ ν 27 ν 15 a’’ a’ Transitions to symmetric levels allowed within Born Oppenhiemer approximation governed by Franck Condon principle [FC bands] and those allowed vibronically by Herzberg-Teller mechanism [HT bands] ∆ν=+1 transitions in asymmetric modes ( and ) possible due to spin-vibronic mechanisms [SV bands] ν 12 a’ ν 10 a’ 60.7 cm -1 ν 11 a’ Transition of Isopropoxy

Spin-Vibronic Mixing Vibronic mixing pseudo Jahn Teller effect Spin orbit mixing Isolated excited state

Spin-Vibronic Transition Moment Symmetric level HT bands Asymmetric level FC bands Spin-Orbit mixing

Experimental spectra and simulation. Experimental Simulation Band Dmitry G. Melnik, Terry A. Miller and Jinjun Liu, TD04, MSS 2013, Columbus

Full simulation, a,b, and c-type c-type (z) b-type (x) a-type (y) Transition Dipole moment Band Dmitry G. Melnik, Terry A. Miller and Jinjun Liu, TD04, MSS 2013, Columbus x y z x z y TDMSim. c (z)0.95 b (x)0.31 a (y)1.00

FC Bands Rotational Contour ν 12 a’ [CO str.] ν 15 a’ [CH 3 torsion] TDMSim. c (z)0.95 b (x)0.31 a (y)1.00 TDMSim. c (z)0.95 b (x)0.31 a (y)1.00

ν 10 a’ [HCO bend] ν 13 a’ [CCCO umbrella] HT Bands Rotational Contour TDMSim. c (z)0.31 b (x)0.31 a (y)0.25 TDMSim. c (z)0.10 b (x)0.90 a (y)1.00

SV Band Rotational Contour ν 26 a’’ [CO wag] TDMSim. c (z)0.95 b (x)0.65 a (y)0.25

Detailed vibronic assignments performed for the t transition of isopropoxy with the aid of quantum chemistry calculations Transitions in stretch and torsion modes allowed within Born Oppenhiemer approximation governed by Franck Condon principle [FC bands] Transitions in bend modes allowed with vibronic Herzberg-Teller mechanism [HT bands] Spin-vibronic mechanism leads to ∆ν=+1 transition in the asymmetric CO wag mode [SV bands] Conclusion

Miller Group Members -Prof. Terry Miller (Advisor) -Neal Kline -Terrance Codd -Meng Huang Acknowledgement

Rotational Contours ν 10 a’ [HCO bend] ν 26 a’’ [CO wag] ν 13 a’ [CCCO umbrella] ν 12 a’ [CO str.] ν 15 a’ [CH 3 torsion]