Nanosecond laser photolysis of the benzene monomer and eximer

A dilute solution of benzene was photolyzed with a KrF excimer laser. The Sn←S1 and Tn←T1 absorption spectra are measured with time-resolved spectroscopy. The Sn←S1 absorptions in the energy range between 850 and 220 nm were analyzed. The transient absorption band at 500 nm, which was observed previously by several workers disappeared completely upon dilution of the sample, and thus was assigned to be the excimer band. We assigned the other states as follows: 620 nm (1E1u, f∼0.003), 540–325 nm (11E2g, f∼0.04), and 270 nm (21E2g, f∼0.12). The observed energies from the ground state to the 11E2g and 21E2g states 7.8 and 9.2 eV, respectively. The Tn←T1 spectrum showed a single peak at 235 nm (f∼0.35) and a shoulder around 310 nm (f∼0.12).