SINGLE EXCITED VIBRATIONAL LEVEL LIFETIMES AND ENERGY-DISSIPATION CHANNELS OF LARGE MOLECULES IN INERT MATRICES

In the present manuscript, we use direct time-resolved, picosecond techniques to determine the vibrational and electronic relaxation processes occurring in large polyatomic molecules - naphthazarin and its deuterated derivatives. The molecules are trapped in low-temperature Ne and Ar matrices and excited by picosecond pulses of a tunable, synchronously pumped dye laser. The S1 fluorescence of naphthazarin exhibits a sharp, well-resolved vibronic structure. Both the decay of the unrelaxed fluorescence from single excited vibronic levels and the rise time on the relaxed emission are observed and resolved in time. In several instances, the relaxed fluorescence rise times are found to be considerably longer than the measured decay times of the excited levels. This is explained in terms of intermediate "bottleneck" states. The lifetimes of these states are much longer in the deuterated species than in normal naphthazarin. It is suggested that these intermediate levels are the "tunneling states" associated with the intramolecular transfer of the phenolic protons. 1985 American Chemical Society.

SINGLE EXCITED VIBRATIONAL LEVEL LIFETIMES AND ENERGY-DISSIPATION CHANNELS OF LARGE MOLECULES IN INERT MATRICES Academic Article