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| Type |
Oral Presentation |
| Area |
Oral Presentation for Young Scholars in Physical Chemistry |
| Room No. |
304호 |
| Time |
THU 09:55-: |
| Code |
PHYS.O-5 |
| Subject |
Real-time Excited State Predissociation Dynamics of Thioanisole |
| Authors |
우경철, 강도형, 김상규*
KAIST 화학과, Korea
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| Abstract |
Relaxation dynamics involving ππ* and nσ* excited states of thioanisole (C6H5SCH3) in the gas phase has been investigated by picosecond time-resolved ion yield (TR-IY) and time-resolved velocity map ion imaging (TR-VMI) methods. It has been widely investigated in our group in the energy-domain [1, 2], and the striking dependence of the relative yields of two reaction channels on the photoexcitation energy was observed as indicated by a ‘dynamic resonance’ in the product branching ratio. Here, with our time-domain measurements, the methyl fragment rise transients were fitted well with single exponential function, except at specific excitation energy range where showing biexponential behavior with two distinct time constants. (c.f. Kinetics of CH3+ rise has been previously reported with fs TR-VMI method [3].) This was also confirmed by the TR-VMI experiment. This implies that two predissociating channels co-exist in the excitation energy region where S1 and S2 are strongly mixed, which may be correlated with the previously reported ‘dynamic resonance’ behavior observed from the energy-domain experiments. This result of two distinct dynamic channels should be emphasized as the first experimental observation in time-domain measurements where excited states of bound and repulsive characters are intensely coupled, which can be generalized throughout the predissociative molecules having ‘Resonance-in-Continuum’ behavior.
References
[1] J. S. Lim, and S. K. Kim, Nat. Chem., 2010, 2, 627
[2] S. Han, J. S. Lim, J.-H. Yoon, J. Lee, S.-Y. Kim and S. K. Kim, J. Chem. Phys., 2014, 140, 054307
[3] G. M. Roberts, et al,, Chem. Sci., 2013, 4, 993
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| E-mail |
starcle@kaist.ac.kr |
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119th General Meeting of the KCS