Dissociative ionization of benzene in intense ultra-fast laser pulses

Based on the possibility of multiphoton ionization of the inner valence electrons in polyatomic molecules, a model was proposed to predict the abundance of different fragments resulting from dissociative ionization of the polyatomic molecules interacting with short laser pulses. According to this model the fragmentation of these molecules occurs through multiphoton ionization of the inner valence electrons, which results in a molecular ion in an excited state. Through radiationless transition the population is transferred to the highly excited levels of the ground electronic state. The molecular ion created in this manner is not stable and dissociates rapidly. To test the applicability of the model, the fragmentation of a benzene molecule interacting with linearly and circularly polarized Ti:sapphire laser pulses was studied. The model was tested by comparing the measured laser-intensity-dependent abundance of C₄H₄⁺ fragment ions with the calculated ones and excellent agreement was obtained with the experimental results.