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MO: Fachverband Molekülphysik

MO 20: Quantenkontrolle

MO 20.1: Poster

Thursday, March 13, 2008, 16:30–19:00, Poster C1

Control of nuclear spin selective rotation of methyl groups and symmetry adapted quantum dynamics — •Thomas Grohmann and Monika Leibscher — Freie Universität Berlin, Institut für Chemie und Biochemie, Takustr. 3, 14195 Berlin

The control of chemical reaction dynamics is currently intensively studied. However, the influence of the nuclear spin is only little investigated although nuclear spin isomers show different behaviour in their nuclear dynamics [1]. It has been shown, that time-dependent magnetic fields induce molecular rotations in methyl groups [2]. Our aim is to simulate the control of molecular torsion in methyl groups in order to create a molecular motor. Nuclear wavefunctions for methyl groups, obeying the anti-symmetry principle, can be constructed using molecular symmetry groups [3]. We derive the symmetry adapted wavefunctions for explicit model potentials describing nuclear torsion and vibration. By solving the time-dependent Schrödinger equation for the three protons in a time-dependent magnetic field we can show that it is only possible to induce unidirectional rotations if dipolar interactions between the nuclear spins are taken into account.

[1] O. Deeb, M. Leibscher, J. Manz, W. von Muellern and T. Seideman, Chem. Phys. Chem. 8 (2007), 322; T. Grohmann, O. Deeb, and M. Leibscher, Chem. Phys. 338 (2007), 252. [2] S. Clough, A.J. Horsewill, M.R. Johnson, J.H. Sutcliffe and I.B.I. Tomsah, Europhys. Lett. 29 (1995), 169. [3] S. Clough and P.J. McDonald, J. Phys. C 16 (1983), 5753.; K.W.H. Stevens, J. Phys. C 16 (1983), 5765.; D. Haase, private communication