Excitation density effect on the decomposition of liquid benzene by ArF excimer laser (193 nm) irradiation

The excitation density effect on the decomposition of liquid benzene has been studied using an ArF excimer laser (λ=193 nm). At low excitation density, biphenyl was primarily produced. At higher laser fluence, large-size aromatic molecules and graphitic carbon were produced. The apparent production yield of biphenyl increases steeply with laser fluence. From the dilution effect of benzene by cyclohexane, we conclude that the steep increase is due to the thermal decomposition induced by the non-radiative decay of optically excited molecules.