Control of elementary chemical reactions by femtosecond light pulses

Essentially new approaches are proposed for controlling the yield of products of a chemical reaction by femto-second laser pulses. The main attention is paid to the method based on the change in phase characteristics of femtosecond pulses. The quantum yield of the product NH(c¹Π) upon multiphoton photodissociation of ammonium in gas is shown to increase by a factor of twelve with chirp variation from –1250 fs² to 2000 fs². It is demonstrated by the example of two-proton transfer in [2,2'-bipyridyl],3,3'-diol in solution that the approach based on the variation in phase characteristics of a pump femtosecond pulse can be also used for controlling reactions in solutions.