title: Ultrafast electron transfer from photoexcited CdSe quantum dots to methylviologen.
abstract: The ultrafast charge separation at the quantum dot (QD)/molecular acceptor interface was investigated in terms of acceptor concentration and the size of the QD. Time-resolved experiments revealed that the electron transfer (ET) from the photoexcited QD to the molecular acceptor methylviologen (MV(2+)) occurs on the fs time scale for large acceptor concentrations and that the ET rate is strongly reduced for low concentrations. The increase in the acceptor concentration is accompanied with a growth in the overlap of donor and acceptor wavefunctions, resulting in a faster reaction until the MV(2+) concentration reaches a saturation limit of 0.3-0.4 MV(2+) nm(-2). Moreover, we found significant QD size dependence of the ET reaction, which is explained by a change of the free energy (ΔG).
authors: Institute of Physical and Theoretical Chemistry, Johann Wolfgang Goethe University Frankfurt/M, Frankfurt, Germany.
authors: Frank
authors: F
authors: Scholz
authors: Lars
authors: L
authors: Dworak
authors: Victor V
authors: VV
authors: Matylitsky
authors: Josef
authors: J
authors: Wachtveitl
mesh_terms: D019187:Cadmium Compounds / Q000737:chemistry*; D004579:Electron Transport; D004583:Electrons; D008027:Light; D008958:Models, Molecular; D036103:Nanotechnology / Q000379:methods*; D010084:Oxidation-Reduction; D010269:Paraquat / Q000737:chemistry*; D010316:Particle Size; D055668:Photochemical Processes / Q000528:radiation effects; D045663:Quantum Dots; D018036:Selenium Compounds / Q000737:chemistry*; D013050:Spectrometry, Fluorescence; D013816:Thermodynamics
chemical_list: D019187:Cadmium Compounds; D018036:Selenium Compounds; D010269:Paraquat