Emission quenching studies of CdS nanoparticles molecularly linked to TiO2: Influence of linker length on interfacial electron transfer yield

PHYS 469

Rachel S. Dibbell and David F. Watson, dwatson3@buffalo.edu. Department of Chemistry, University at Buffalo, Buffalo, NY 14260-3000
We present spectroscopic evidence for photoinduced electron transfer between CdS and TiO2 nanoparticles molecularly linked by mercaptoalkanoic acids (MAAs). CdS suspensions exhibit steady-state emission centered at 590 nm. The addition of TiO2 and mercaptopropionic acid (MPA) to CdS suspensions quenches the emission. Increasing the concentration of MPA from 0 to 4.57 x 10-4 M, at constant CdS and TiO2 concentrations, results in (96.7 ± 0.1)% emission quenching and a substantial decrease in the emission lifetime. MPA alone causes (52 ± 1)% emission quenching, while TiO2 alone causes (30 ± 5)% quenching. Little or no change of the emission lifetime is observed for quenching by MPA or TiO2 alone. Taken together, these data suggest that MPA facilitates interfacial electron transfer from photoexcited CdS to TiO2. Nanosecond transient absorption measurements are also consistent with interfacial electron transfer. Increasing the chain length of MAAs reduces the interfacial electron transfer yield.
 

PHYS Poster Session - Nanostructured Materials and Nanophotonics
7:30 PM-10:00 PM, Wednesday, April 9, 2008 Morial Convention Center -- Hall A, Poster

Division of Physical Chemistry

The 235th ACS National Meeting, New Orleans, LA, April 6-10, 2008