Coherent Control of Bond Making.

Abstract

We demonstrate for the first time coherent control of bond making, a milestone on the
way to coherent control of photo-induced bimolecular chemical reactions. In strong-
field multiphoton femtosecond photoassociation experiments, we find the yield of 
detected magnesium dimer molecules to be enhanced for positively chirped pulses and 
suppressed for negatively chirped pulses. Our ab initio model shows that control is 
achieved by purification via Franck-Condon filtering combined with chirp-dependent 
Raman transitions. Experimental closed-loop phase optimization using a learning 
algorithm yields an improved pulse that utilizes vibrational coherent dynamics in 
addition to chirp-dependent Raman transitions. Our results show that coherent control 
of binary photo-reactions is feasible even under thermal conditions.