Two different cases, (1) thermal initiation and (2) collisionless IR multiple photon
(MP) initiation, of initiating the model reaction of the successive decay of polyatomic
molecules ABC → AB + C,AB → A + B are considered for the case when the intermediate
product AB is desired. In the case when the desired product AB is thermally less
stable than the original one ABC the high output of AB under the thermal initiation
is impossible. However by means of IR MP initiation one can obtain a high yield of
the desired product, i.e., nearly 100%. The reduction of the chemical reaction pathways
takes place for the IR MP initiation. This is due to the extreme intermolecular
nonequilibrium achieved under IR MP initiation of the reaction. Unlike the thermal
initiation when all the reaction products are of equally high temperature, under IR
MP initiation the temperature of the intermediate product TAB is lower than that of
the original one TABC and a further decay of the AB species does not occur.
Reduction of the Pathways of Photochemical Gasphase Reactions
Induced by Multiple Photon IR Laser Excitation of Molecules