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Resonance Raman Investigation of the Interaction between Aromatic Dithiocarbamate Ligands and CdSe Quantum Dots
journal contribution
posted on 2017-03-15, 00:00 authored by Jamie
J. Grenland, Chen Lin, Ke Gong, David F. Kelley, Anne Myers KelleyLigand
exchange with phenyl dithiocarbamates is known to significantly
red-shift the lowest excitonic transition of CdSe quantum dots. Here
we show that the resonance Raman spectra of CdSe quantum dots treated
with p-methoxyphenyldithiocarbamate are nearly identical
to those of CdSe quantum dots to which thin CdS shells have been added
by standard synthetic methods. We conclude that the dithiocarbamate
ligands decompose and react with Cd2+ not fully removed
following the synthesis to form CdS on the surface of the quantum
dots. This red-shifts the absorption spectrum primarily by delocalizing
the electron into the CdS shell. These results are consistent with
the common use of aliphatic dithiocarbamates as single-source precursors
for adding ZnS or CdS shells to CdSe quantum dots and with the recent
demonstration through NMR that phenyldithiocarbamate ligands decompose
during nanocrystal ligand exchange.