Ultrafast Non-Förster Intramolecular Donor-Acceptor Excitation Energy Transfer.
Ultrafast intramolecular electronic energy transfer in a conjugated donor-acceptor system is simulated using nonadiabatic excited-state molecular dynamics. After initial site-selective photoexcitation of the donor, transition density localization is monitored throughout the S2→ S1internal conversion process, revealing an efficient unidirectional donor → acceptor energy-transfer process. Detailed analysis of the excited-state trajectories uncovers several salient features of the energy-transfer dynamics. While a weak temperature dependence is observed during the entire electronic energy relaxation, an ultrafast initially temperature-independent process allows the molecular system to approach the S2-S1potential energy crossing seam within the first ten femtoseconds. Efficient energy transfer occurs in the absence of spectral overlap between the donor and acceptor units and is assisted by a transient delocalization phenomenon of the excited-state wave function acquiring Frenkel-exciton character at the moment of quantum transition.
Departamento de Física, Universidad Carlos III de Madrid , Avenida Universidad 30, 28911 Leganés, Madrid, Spain.|Experimental Physics II, University of Bayreuth , Bayreuth 95440, Germany.
Stavros
http://orcid.org/0000-0003-0753-2643
S
Athanasopoulos
Universidad Nacional de Quilmes/CONICET , Roque Saenz Peña 352, B1876BXD Bernal, Argentina.
Laura
L
Alfonso Hernandez
Laboratory for Chemistry of Novel Materials, University of Mons , Place du Parc 20, B-7000 Mons, Belgium.
David
D
Beljonne
Universidad Nacional de Quilmes/CONICET , Roque Saenz Peña 352, B1876BXD Bernal, Argentina.
Sebastian
S
Fernandez-Alberti
Theoretical Division, Center for Nonlinear Studies (CNLS) and Center for integrated Nanotechnologies (CINT), Los Alamos National Laboratory , Los Alamos, New Mexico 87545, United States.
Sergei
S
Tretiak