A chemisorbed polyfunctional molecule containing both a S atom and a Cl atom, (2-chloroethylethyl sulfide, 2-CEES) is able to abstract electrons which reside near the bottom of the conduction band in TiO2 occurs only into the molecule containing the Cl moiety. This suggests that a specific electron transfer pathway involving the Cl atom is involved in the electron transfer interaction of 2-CEES with TiO2. Small coverages of adsorbed electron acceptor molecules are found to cause electron depletion of individual TiO2 crystallites. (C) 2004 Elsevier B.V. All rights reserved.