XVIth International Workshop on
Quantum Systems in
Chemistry and Physics
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Control of Vibrational Dynamics and Reaction of C60 and Its Derivatives by Near-infrared Fields
Hirohiko Kono,1 Naoyuki Niitsu,1 Kaoru Yamazaki,1 Katsunori Nakai,2 Mikito Toda,3 and Stephan Irle4
1Department of Chemsitry, Graduate School of Science, Tohoku University, Sendai 980-8578, Japan.
2Department of Chemistry, School of Science, The University of Tokyo, Tokyo 113-0033, Japan.
3Department of Physics, Faculty of Science, Nara Women's University, Nara 630-8506, Japan.
4Department of Chemistry, Graduate School of Science, Nagoya University, Nagoya 464-8601, Japan
We developed the time-dependent (TD) adiabatic state approach to investigate the electronic and nuclear dynamics of polyatomic molecules in intense laser fields, where the total wave function is expanded in terms of TD adiabatic states defined as the eigenfunctions of the "instantaneous" electronic Hamiltonian including the dipole interaction with a laser field [1]. Nuclear dynamics of a molecule in a near-infrared (IR) field can be described by classical molecular dynamics on TD potentials. By using this approach combined with ab initio electronic structure calculations, we investigated the dynamics of C60 interacting with intense IR pulses and found that large-amplitude vibration with energy of > 20 eV is induced mainly in the oblate-prolate hg(1) mode of C60 and its cations [2]. We also demonstrated that large-amplitude vibration of the hg(1) mode persists for 2-5 ps. This means that mode selectivity is achieved by adjusting the intervals between pulses in a pulse train. We then investigated the fragmentation dynamics of C60 on the ns time scale by using a DFTB method. It is confirmed that the main process is C2-elimination after Stone-Wales (SW) rearrangements due to rapid vibrational energy migration in the carbon network. A SW rearrangement occurs within 100 fs only when a sufficient energy to go over the transition state is localized in a C=C bond and its surrounding C atoms and the induced motion fits the direction of the transition state. This suggests the controllability of this local rearrangement leading to the optimization of branching ratios of fragments, though fragmentation in the ns range is considered "statistical." We have also investigated the field-induced dynamics of polyhydroxy fullerenes by using the DFTB method and found that hydroxy groups migrate rapidly in the carbon netowork and water molecules are ejected from the parent molecule. These processes are considered key steps for the transformation of polyhydroxy fullerenes into single-walled nanotubes, multiwalled nanotubes and carbon onions [3].

[1] Y. Sato, H. Kono, S. Koseki and Y. Fujimura, J. Am. Chem. Soc. 125, 8019(2003).
[2] K. Nakai, H. Kono, Y. Sato, N. Niitsu, R. Sahnoun, M. Tanaka and Y. Fujimura, Chem. Phys. 338, 127(2007).
[3] V. Krishna, N. Stevens, B. Koopman and B. Moudgil, Nature Nanotech. 5, 330(2010).

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