Ligand exchange of CdSe nanocrystals probed by optical spectroscopy in the visible and mid-IR

Optical spectroscopy in the UV/VIS and mid-IR spectral range was applied for a quantitative analysis of ligand exchange in CdSe semiconductor nanocrystals. CdSe cores from a single synthesis run were used for the study in order to ensure identical starting conditions for the exchange of different ligand molecules. From the analysis of the mid-IR spectrum the binding of the ligand molecules was monitored and the ligand exchange rate was obtained. DFT calculations yielded the vibrational normal modes of the system CdSe/ligand and allowed the identification of specific marker bands for the binding of different ligands to the nanocrystal surface.