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Coupled Exciton and Charge-Transfer Resonances in the Raman Enhancement of Phonon Modes of CdSe Quantum Dots (QDs)

NCJ Number
Journal of Physical Chemistry C Volume: 118 Issue: 33 Dated: 2014 Pages: 19415–19421
Date Published
7 pages

This article reports on a project that observed the enhancement of a transverse optical (TO) phonon mode of e1 symmetry and a normally forbidden surface optical (SO) phonon mode of b1 symmetry in CdSe quantum dots (QDs) due to adsorption of 4-mercaptopyridine molecules.


The former was observed in 3, 4, and 5 nm diameter particles, while the latter was observed only in the 2 nm particles. Maximum enhancement of the phonon modes was obtained through a coupling of the charge-transfer transition and the exciton transition, which are in resonance with the laser energy. Selection rules, using Herzberg–Teller (vibronic) coupling, were invoked to explain the observed enhancements. (publisher abstract modified)

Date Published: January 1, 2014