Dietzek Benjamin, Yartsev Arkady, Tarnovsky Alexander N
Department of Chemical Physics, Lund University, P.O. Box 124, 22100 Lund, Sweden.
J Phys Chem B. 2007 May 3;111(17):4520-6. doi: 10.1021/jp066471a. Epub 2007 Apr 7.
The photoinduced excited-state processes in 1,1'-diethyl-2,2'-cyanine iodine are investigated using femtosecond time-resolved pump-probe spectroscopy. Using a broad range of probe wavelengths, the relaxation of the initially prepared excited-state wavepacket can be followed down to the sink region. The data directly visualize the directed downhill motion along the torsional reaction coordinate and suggest a barrierless excited-state isomerization in the short chain cyanine dye. Additionally, ultrafast ground-state hole and excited-state hole replica broadening is observed. While the narrow excited-state wavepacket broadens during pump-probe overlap, the ground-state hole burning dynamics takes place on a significantly longer time-scale. The experiment reported can be considered as a direct monitoring of the shape and the position of the photoprepared wavepacket on the excited-state potential energy surface.
