title: Nonuniform Excitonic Charge Distribution Enhances Exciton-Phonon Coupling in ZnSe/CdSe Alloyed Quantum Dots.
abstract: Zinc to cadmium cation exchange of ZnSe quantum dots has been used to produce a series of alloyed Zn1-xCdxSe quantum dots. As x increases and the lowest-energy exciton shifts to the red, the peak initially broadens and then sharpens as x approaches 1. Resonance Raman spectra obtained with excitation near the lowest excitonic absorption peak show a gradual shift of the longitudinal optical phonon peak from 251 cm-1in pure ZnSe to 210 cm-1in nearly pure CdSe with strong broadening at intermediate compositions. The LO overtone to fundamental intensity ratio, a rough gauge of exciton-phonon coupling strength, increases considerably for intermediate compositions compared with those of either pure ZnSe or pure CdSe. The results indicate that partial localization of the hole in locally Cd-rich regions of the alloyed particles increases the strengths of local internal electric fields, increasing the coupling between the exciton and polar optical phonons.
authors.affiliation: Chemistry & Chemical Biology, University of California, Merced , 5200 North Lake Road, Merced, California 95343, United States.
authors.forename: Ke
authors.identifier: http://orcid.org/0000-0003-1627-6979
authors.initials: K
authors.lastname: Gong
authors.affiliation: Chemistry & Chemical Biology, University of California, Merced , 5200 North Lake Road, Merced, California 95343, United States.
authors.forename: David F
authors.initials: DF
authors.lastname: Kelley
authors.affiliation: Chemistry & Chemical Biology, University of California, Merced , 5200 North Lake Road, Merced, California 95343, United States.
authors.forename: Anne Myers
authors.identifier: http://orcid.org/0000-0002-4073-109X
authors.initials: AM
authors.lastname: Kelley