Page "CRESU experiment" Paragraph 2

Chemical kinetics experiments can then be carried out in a " pump-probe " fashion using a laser to initiate the reaction ( for example by preparing one of the reagents by photolysis of a precursor ), followed by observation of that same species ( for example by laser-induced fluorescence ) after a known time delay.

The fluorescence signal is captured by a photomultiplier a known distance downstream of the de Laval nozzle.

The time delay can be varied up to the maximum corresponding to the flow time over that known distance.

By studying how quickly the reagent species disappears in the presence of differing concentrations of a ( usually stable ) co-reagent species the reaction rate constant at the low temperature of the CRESU flow can be determined.