Stepwise ionization of hydroquinone vapor by monochromatic radiation

Processes of stepwise ionization of hydroquinone vapor by radiation in the range 315-275 nm were studied using photoionization spectroscopy techniques . The two-step ionization process yielding molecular ions was found to prev ail at a laser power density up to similar to 10(7) W/cm(2). As the radiati on intensity increases, the progressively stronger and deeper degradation t akes place via dissociation of the molecular and, probably, fragment ions d ue to absorption of at least one additional photon. The slow process of the formation of C5H6O+ ions at an effective rate constant of the order of 10( 6) s(-1) was observed.