117308-91-5Relevant academic research and scientific papers
Ultrafast Electron Transfer in Optically Prepared "Simple" Ion Pairs: The Mechanism at High Donor Concentration
Jarzeba, Wlodzimierz,Thakur, Khalid,Hoermann, Aldo,Barbara, Paul F.
, p. 2016 - 2023 (1995)
The ultrafast spectroscopy of the charge-transfer band of the benzene/Br atom electron donor-acceptor EDA complex and related complexes of various alkylated benzenes with Br atoms (arene/Br) have been investigated in several solvents at high donor concentrations.The excited state of the complex, a contact ion pair, is observed to decay (by charge recombination) with non-first-order kinetics on several time scales.Various aspects of the transient spectroscopy are investigated in detail.The previously described enhancement of the recombination rate at high donor concentration is observed to be general.Even donors with sterically bulky substituents show the rate enhancement at high concentration, precluding dimer cations as intermediates.The paper also reports observations of coherent vibrational motion in the mesitylene/Br complex ground state, initiated by impulsive excitation of the charge-transfer band.Finally, ab initio calculations of the computationally accessible complex benzene/Cl are reported, indicating that the equilibrium geometry has C5 symmetry with the Cl atom positioned over the C-C bond, i.e., a ? complex.A ? complex of comparable energy is also observed.The various results are discussed in relation to the charge-recombination mechanism of the contact ion pair of the arene/Br complexes.
Ultrafast Relaxation and Electron Transfer in Optically Prepared "Simple" Ion Pairs
Hoermann, Aldo,Jarzeba, Wlodzimierz,Barbara, Paul F.
, p. 2006 - 2015 (2007/10/02)
An extensive investigation of the ultrafast pump-probe spectroscopy of the charge-transfer band of the mesitylene/Br EDA complex and related complexes in various solvents and over a broad range of UV, visible, and near-IR probe wavelangths is described.The data allow for a measurement of the charge-recombination kinetics which exhibits a distribution of rate constants, including an initial very fast component (τca.1 ps),a factor of >1000 slower component, and intermediate-rate processes.The nonexponential kinetics may be associated with a distribution of arene+/Br- acceptor geometries in the initially prepared state of the ion pair.The complex kinetics are discussed in terms of contemporary electron-transfer theory, which indicates that the most likely source of the dramatically nonexponential kinetics is an inner-sphere effect involving specific, configurationally dependent electronic interactions of the donor and acceptor.The reaction kinetics particularly at early times, is not strongly sensitive to solvent polarity or solvation dynamics, further supporting that mainly the donor/acceptor electronic interactions are dominating the kinetics.The data also reveal features due to the local transition on the transient D+ species in the ion pair and evidence of vibrationally unrelaxed absorption due the initially re-formed complex subsequent to charge recombination.
Ultraviolet/Visible Spectra of Halogen Molecule/Arene and Halogen Atom/Arene ?-Molecular Complexes
Raner, K. D.,Lusztyk, J.,Ingold, K. U.
, p. 564 - 570 (2007/10/02)
Ultraviolet/visible spectra have been recorded for chlorine, bromine, and iodine atom ?-molecular complexes with a number of aromatic compounds.The visible spectra of the I./arene complexes show charge-transfer (CT) bands whose transition energ
