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MO: Fachverband Molekülphysik
MO 14: Vibrational and Rotational Spectroscopy
MO 14.5: Vortrag
Mittwoch, 11. März 2020, 15:30–15:45, f142
Dynamics of polar polarizable rotors acted upon by unipolar electromagnetic pulses — •Mallikarjun Karra1, Marjan Mirahmadi2, Burkhard Schmidt2, and Bretislav Friedrich1 — 1Fritz-Haber-Institut der Max-Planck-Gesellschaft, Berlin, Germany — 2Institut für Mathematik, Freie Universität Berlin, Berlin, Germany
We study, analytically as well as numerically, the dynamics that arises from the interaction of a polar polarizable rigid rotor with single unipolar electromagnetic pulses of varying length with respect to the rotational period of the rotor. In the sudden, non-adiabatic limit, we derive analytic expressions for the rotor's wavefunctions, kinetic energies, and field-free evolution of orientation and alignment. The corresponding time-dependent Schrödinger equation is solved numerically in the finite pulse-width regime, extending all the way to the adiabatic limit where general analytic solutions beyond the field-free case are no longer available. The effects of the orienting and aligning interactions as well as of their combination on the post-pulse populations of the rotational states are visualized as functions of the orienting and aligning kick strengths in terms of population quilts, while the evolution of the wavepacket itself is visualized in terms of space-time probability densities. In the intermediate temporal regime, we find that the wavepackets as functions of the orienting and aligning kick strengths show resonances that correspond to diminished kinetic energies at particular values of the pulse duration. Based on this surprising finding, we propose a scheme for the rotational cooling of molecules via iterative `braking'.