Pump-shaped dump optimal control reveals the nuclear reaction pathway of isomerization of a photoexcited cyanine dye.
Using optimal control as a spectroscopic tool we decipher the details of the molecular dynamics of the essential multidimensional excited-state photoisomerization - a fundamental chemical reaction of key importance in biology. Two distinct nuclear motions are identified in addition to the overall bond-twisting motion: Initially, the reaction is dominated by motion perpendicular to the torsion coordinate. At later times, a second optically active vibration drives the system along the reaction path to the bottom of the excited-state potential. The time scales of the wavepacket motion on a different part of the excited-state potential are detailed by pump-shaped dump optimal control. This technique offers new means to control a chemical reaction far from the Franck-Condon point of absorption and to map details of excited-state reaction pathways revealing unique insights into the underlying reaction mechanism.
Dietzek
Benjamin
B
Department of Chemical Physics, Lund University, P.O. Box 124, SE-22100 Lund, Sweden. dietzek@mit.edu
Brüggemann
Ben
B
Pascher
Torbjörn
T
Yartsev
Arkady
A
D002232:Carbocyanines / Q000737:chemistry*; D007536:Isomerism; D007700:Kinetics; D008958:Models, Molecular; D010777:Photochemistry
D002232:Carbocyanines