Dynamics of the first excited state of the decatungstate anion studied by subpicosecond laser spectroscopy

The primary events in decatungstate photolysis are investigated by subpicos econd spectroscopy. Steady-state and picosecond fluorescence experiments ar e also reported. The absorption peak at 776 nm of the transient state calle d X, involved in photocatalytic reactions with organic substrates on the na nosecond time scale, rises in a few ps after subtle changes of an initial b and, extending from the visible to the near-infrared (NIR). The decay in th e NIR edge occurs in 25 ps in acetonitrile and 15 ps in water. X is interpr eted as a delocalized ligand-to-metal charge transfer (LMCT) excited state, originating from a localized excited state absorbing in the NIR. Re-excita tion of X could contribute to the 580 nm fluorescence observed under picose cond excitation. (C) 1999 Elsevier Science B.V. All rights reserved.