Nonadiabatic chemistry in the pi-sigma*-mediated predissociation dynamics of polyatomic molecules

Sang Kyu Kim
Department of Chemistry, KAIST, Daejeon (34141), Korea.
[email protected]

Nonadiabatic dynamics are ubiquitous in nature. We are going to introduce some unique examples where we could investigate nonadiabatic transition processes at the molecular level in both spatial and temporal domains. Photo-induced processes including predissociation, tunneling, nonradiative transitions of internal conversion and intersystem crossing, or photo-detachment are often associated with nonadiabatic transitions facilitated in the vicinity of conical intersections. As the conical intersection is multi-dimensional in nature, it is usually not straightforward to figure out the strong coupling region in terms of structure and energetics. We are here demonstrates that it is quite possible to prepare the reactive flux in the proximity of the conical intersection volume to unravel the detailed nonadiabatic bifurcation dynamics mechanism in molecular details. Various experimental tools such as resonant-enhanced ionization, Stark-deflection, hole-burning, IR+UV double resonances, (slow) velocity-map ion/electron imaging, or pump-probe based photofragment action spectroscopy have been employed to get hints about the microscopic mechanism of the excited-state chemistry of neutrals and anionic species at very low temperatures. Spectroscopic technique has pros and cons in terms of structural identification. Here, we are going to show how we could possibly characterize structures of the conical intersections or transition states where the molecule stays only briefly in the (3N-6) normal mode space where N is the number of atoms in polyatomic systems.

References
[1] J. S. Lim, H. S. You, S. Y. Kim, S. K. Kim, Chem. Sci., 10 2404 (2019).
[2] K. C. Woo, S. K. Kim, J. Phys. Chem. A, 123 1529 (2019).
[3] H. S. You et. al., J. Phys. Chem. A, 122 1197 (2018).
[4] K.-C. Woo, D. H. Kang, S. K. Kim, J. Am. Chem. Soc., 139 17152 (2017).
[5] H. S. You et. al. Int. Rev. Phys. Chem., 34 429 (2015).
[6] H. S. You et. al., J. Phys. Chem. Lett., 6 3202 (2015).
[7] J. Lim, S. K. Kim, Nat. Chem., 2 627 (2010).
[8] K.-C. Woo, S. K. Kim, J. Phys. Chem. Lett., 11 161 (2020).
[9] J. S. Lim et. al., J. Chem. Phys., 151 244305 (2019).