RAMAN-SCATTERING STUDY OF EXCITON-PHONON COUPLING IN PBS NANOCRYSTALS

The exciton-phonon coupling strength of PbS nanocrystals that strongly confine both charge carriers is investigated using resonant Raman sca ttering. The strength of this coupling (Huang-Rhys parameter S similar to 0.7) is four orders of magnitude greater than that predicted theor etically for the intrinsic states of the nanocrystal, but is the same order of magnitude as that measured for Cd(S,Se) nanocrystals. The lar ge exciton-phonon coupling is consistent with one charge carrier being localized at the surface of the nanocrystal.