In selected spectral regions, the UV fission of the bond between a carbon and a halogen atom in haloalkanes can happen explosively, in timescales of the order of tens of femtoseconds. Tunable ultrashort laser pulses like those available at the CLUR (Centre for Ultrafast Lasers, at the Complutense University of Madrid) in combination with velocity map imaging techniques are necessary to follow this type of photoinduced reactions in real time.

A team of Spanish researchers involved in the XLIC Action has demonstrated a powerful scheme that goes beyond the description of the reaction, and is capable of controlling its course. The mechanism involves employing an additional “control” laser pulse that modifies (“dresses”) the potential energy surfaces, producing changes in the outcome of the reaction and the speed of the fragments. Theoretical simulations have shown how the essential new tool for the maximum degree of control is to provoke rapid changes between the field-free regime and the “dressed states” regime.

Figure NatChem

This work demonstrates that fine control of the properties of this “control” laser pulse turns it into a true “photonic scalpel” capable of manipulating chemical reactions, as well as shedding new light into the dynamics of complex molecular dynamical processes.

Their work has been published in the journal Nature Chemistry on July 20, 2014.

M. E. Corrales, J. González-Vázquez, G. Balerdi, I. R. Solá, R. de Nalda, L. Bañares, Control of ultrafast molecular photodissociation by laser field induced potentials, Nature Chemistry (2014), doi:10.1038/nchem.2006

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