Heidelberg 2015 – scientific programme
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MO: Fachverband Molekülphysik
MO 2: Quantum Control
MO 2.3: Talk
Monday, March 23, 2015, 12:15–12:30, PH/HS1
Photoassociation of hot magnesium atoms by phase-shaped femtosecond pulses — •Wojciech Skomorowski1, Liat Levin2, Leonid Rybak2, Ronnie Kosloff3, Christiane P. Koch1, and Zohar Amitay2 — 1Theoretische Physik, Universität Kassel, Heinrich-Plett-Str. 40, 34132 Kassel, Germany — 2The Shirlee Jacobs Femtosecond Laser Research Laboratory, Schulich Faculty of Chemistry, Technion-Israel Institute of Technology, Haifa 32000, Israel — 3Fritz Haber Research Centre and The Department of Physical Chemistry, Hebrew University, Jerusalem 91904, Israel
One of the long-standing goals in the field of coherent control is the control of photo-induced bimolecular chemical reactions. Realizing this goal will create a new type of photochemistry with selective control of yields and branching ratios. Shaped laser pulses can act there as special catalysts which drive molecular process to a desired channel. Here we show coherent control of bond making, a milestone on the way to the control of photo-induced chemical reactions. The control is demonstrated in the process of multiphoton photoassociation of hot magnesium atoms by phase-shaped femtosecond laser pulses. We find the yield of observed Mg2 molecules to be strongly enhanced for positively chirped pulses and suppressed for negatively chirped pulses. Our fully ab initio model, combining electronic structure calculations with quantum molecular dynamics, shows that control is achieved by purification via Franck-Condon filtering coupled with chirp-dependent Raman transitions. The presented results prove that coherent control of binary photo-reactions is feasible even under thermal conditions.