Study of the Formation Dynamics of OH from the Photolysis of O3 by Ultrashort Laser Pulses.

We report the first experimental detection of the laser-induced formation dynamics of OH under normal pressure, which was observed using the pump-probe scheme with two 250 fs laser pulses at 282.2 nm. The first laser photolyzes O3 to form OH, and the second laser excites OH to induce fluorescence at 308 nm. The fluorescence cannot be detected with a single beam because the femtosecond pulses have already passed through the sample before the formation of OH from their own photolysis. A photochemical dynamic model was built, and the experimental results are in good agreement with the model. This method can also be used for other OH-related dynamic measurements, which can effectively avoid laser-generated interference from the photolysis of O3.