Tracking ultrafast excited-state bond-twisting motion in solution close to the Franck-Condon point.
Applying optimal control to photoinduced trans-cis isomerization in condensed phase, the dynamics of bond-twisting motion of 1,1'-diethyl-4,4'-cyanine in methanol and propanol is revealed. The shape of the optimized pulse resulting from minimization of the photoisomer formation can be directly related to the initial excited-state dynamics in close proximity to the Franck-Condon point. The solvent viscosity-dependent ultrafast wavepacket motion is reflected in the prominent down-chirp of the optimized pulses and reveals a detailed picture of the control mechanism: The reduction of the isomer production is achieved by most efficient dumping of excited population back to the trans ground state. In the higher-viscosity solvent, propanol, wavelength-dependent oscillatory features are superimposed to the overall chirp structure pointing to the importance of excited-state vibrational coherences for the dumping process.
Dietzek
Benjamin
B
Department of Chemical Physics, Lund University, Lund, Sweden. dietzek@ mit.edu
Pascher
Torbjörn
T
Yartsev
Arkady
A
D000433:1-Propanol / Q000737:chemistry*; D002232:Carbocyanines / Q000737:chemistry*; D000432:Methanol / Q000737:chemistry*; D015394:Molecular Structure; D010777:Photochemistry; D011789:Quantum Theory; D012996:Solutions / Q000737:chemistry; D013237:Stereoisomerism; D013816:Thermodynamics; D013997:Time Factors; D014732:Vibration
D002232:Carbocyanines; D012996:Solutions; C067343:kryptocyanine; D000433:1-Propanol; D000432:Methanol