Key points are not available for this paper at this time.
We report the observation of 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 is observed in 3, 4, and 5 nm diameter particles, while the latter is observed only in the 2 nm particles. Maximum enhancement of the phonon modes is 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 are invoked to explain the observed enhancements.
Islam et al. (Tue,) studied this question.