Femtosecond laser control of chemical reactions

Abstract

Femtosecond laser control of chemical reactions is made possible through the use of pulse-shaping techniques coupled to a learning algorithm feedback loop – teaching the laser pulse to control the chemical reaction. This can result in controllable relative fragmentation ratios for unimolecular dissociation reactions – therefore selectively breaking bonds in a molecule. More interestingly, the same techniques can be used to provide control over chemical reactions involving two or more reactant molecules, where these come together, react and produce new reaction products. The reaction product ratios can be controlled in this way, providing a new form of selectivity in addition to the usual variation of temperature, pressure and catalysts in chemical reactions. In this work, low-pressure gas-phase laser-induced chemical reactions were studied, with the aim of controlling the reaction between CO and H2 to produce hydrocarbon products of interest to the petrochemicals industry. Preliminary experimental results are presented.