Electronic Properties of Q-CdS Clusters Stabilized by Adenine

Adenine-capped Q-CdS has been synthesized in an aqueous medium. IR spectroscopy indicates an interaction between Q-CdS and adenine through Cd(2+). The amount of adenine controls the size of the clusters. A typical 5x10(-3) mol dm(-3) of adenine produces nanoclusters having the onset of absorption and an emission band at 2.8 and 2.35 eV, respectively. Adenine binds to the shallower traps and enhances the emission intensity of the 530-nm band without causing any shift in emission. Thermolysis of these colloids leads to the production of larger CdS clusters with changed electronic properties. Relaxation kinetics of charge carriers shows their average lifetime to increase with a decrease in particle size. Illumination of these particles does not lead to their photodissolution. This catalyst is, however, photoactive. The addition of indole causes the quenching of its emission. The photocatalytic oxidation of indole produces indigo with a quantum efficiency of 0.03. Copyright 2001 Academic Press.