München 2004 – wissenschaftliches Programm

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MO: Molekülphysik

MO 21: Ultrakurze Lichtimpulse: Quantenkontrolle (gemeinsame Sitzung mit Fachverband Q)

MO 21.6: Vortrag

Freitag, 26. März 2004, 12:15–12:30, HS 223

Quantum Control of Bond Breaking in Triatomic Systems using Few-Cycle IR + UV Laser Pulses — •Nadia Elghobashi, Leticia González, and Jörn Manz — Institut für Chemie, Physikalische und Theoretische Chemie, Freie Universität Berlin, Takustrasse 3, D-14195 Berlin, Germany

Few-cycle infrared (IR) plus ultraviolet (UV) laser pulses can excite coherent vibrations, inducing selective dynamical changes in bond lengths, momenta, etc. In symmetric molecules, these pulses can induce dynamical symmetry breaking. Here, such pulses shall be applied to triatomic hydrogen-bonded molecules, XHY, to induce dynamical changes in bond lengths which may lead to selective bond-breaking, i.e. XHY → X + HY or XH + Y. The mechanism begins with an initial well-crafted, few-cycle IR laser pulse that drives the hydrogen away from its equilibrium position in the electronic ground state or provides it with appropriate momentum. After an optimized time delay, a second, few-cycle UV laser pulse is applied, thus photodetaching an electron or exciting the system to an unbound potential energy surface (PES). Evolution of the pre-excited system on the excited surface results in bond-selective dissociation.

Exemplarily, two dimensional (2D) ab initio and quantum dynamical simulations will be discussed for the symmetric FHF⁻ molecule and other asymmetric systems, like HOD and OHF⁻.