Douglas Magde; Maurice W Windsor; WASHINGTON STATE UNIV PULLMAN Dept. of CHEMISTRY.
On the basis of measurements made using the second harmonic of a mode-locked Nd(3+) laser, the authors demonstrate that the efficient quenching of the lowest excited singlet state in the dye, crystal violet involves rapid repopulation of the ground state in less than 10 to the -11th power sec. The repopulation time exhibits a cube root dependence on solvent viscosity. They argue that the data are best explained by a deactivation involving direct S(1) to S(0) internal conversion. They suggest that the class of triphenyl and diphenylmethane dyes should prove to be more efficient and versatile bleachable shutters and passive mode-locking elements for laser construction than any dyes currently in use in the visible region of the spectrum. (Modified author abstract).