Optical Free Induction and Fluorescence Decay of Pentacene in p-Terphenyl Following Narrow Band Laser Excitation

Optical free induction and fluorescence decay experiments on pentacene following narrow band laser excitation are reported. From the results we conclude that pentacene for its lowest 1B2u ← 1A1g transition is a perfect two-level system and from the power saturation term in the OFID we calculate a transition dipole moment of 1.5 ± 0.2 debye. A long-lived transient observed in the fluorescence during the onset of cw dye laser excitation is ascribed to a bottle-neck in the optical pumping cycle.