Characteristics of the interaction between resonance ultraviolet laser radiation and nitroaromatic crystals

An experimental study demonstrated the selective nature of the interaction of ultraviolet laser radiation with some nitroaromatic compounds directly in the condensed phase when (π,π*) electronic transitions took place in molecules. This occurred in molecular condensed systems with a strong (τ_ic~10^–12sec) intercombination conversion and a large absorption cross section σ_π,π*~5×10^–17cm². Therefore, in spite of the high rates of relaxation processes in the condensed phase, it was possible to saturate the triplet levels by resonance laser radiation and to observe selective dissociation of molecules by single- and double-stage mechanisms, so that the dissociation yield was an order of magnitude higher than the evaporation yield.