ULTRAFAST PHOTOINDUCED CHARGE SEPARATION AND RECOMBINATION IN WEAKLY-BOUND COMPLEXES BETWEEN OXAZINE DYES AND N,N-DIMETHYLANILINE

The association constants between cresyl violet (CV) and oxazine 170 ( OX) with N,N-dimethylaniline (DMA) were determined for methanolic solu tion to be 0.3 +/- 0.15 l/mol and 0.1 +/- 0.06 l/mol. One-colour pump- probe experiments showed a biphasic recovery of the ground state absor ption. The short-lived component is assigned to the fast electron back -transfer within dye-amine complexes (1.4 +/- 0.2 ps for CV and 2.0 +/ - 0.3 ps for OX), because the observed reduction in maximum bleaching parallels the amount of dye bound in weak complexes with DMA.