Ultrafast dynamics of the excited methylviologen-iodide charge transfer complexes

The ultrafast dynamics of the excited charge transfer complexes between met hylviologen and iodide ions has been investigated in aqueous solutions of p otassium iodide using femtosecond transient absorption spectroscopy. Methyl viologen and iodide form 1:1 and 1:2 charge transfer complexes characterize d by charge transfer bands in the same spectral region. Transient absorptio n of the complexes has been studied after ultrafast excitation in their cha rge transfer band. The excitation of the 1:1 complex results in the formati on of the MV+./I-. radical pair while the excitation of the 1:2 complex is leading to the formation of the MV./I-. and MV+./I-2 radical pairs. (C) 200 1 Elsevier Science B.V. All rights reserved.