Exciton-LO-phonon interaction of CuCl spherical quantum dots studied by resonant hyper-Raman spectroscopy

Resonant hyper-Raman-scattering spectroscopy was applied for studies of the exciton-LO-phonon interaction in spherical CuCl nanocrystals of different sizes embedded in a glass matrix. Both the LO and 2LO phonon bands have shown a prominent resonance with the lowest energy 1S confined exciton state. The ratio of the integral intensities of the LO and 2LO bands rho was found to increase with increase of the incident photon energy, or decrease of the nanocrystal radius. The Huang-Rhys factor S has been calculated as a function of the nanocrystal size from the experimentally measured values of rho on the offset harmonic-oscillator model of electron-vibrational coupling. It has been found that S increases monotonically from 0.22 to 0.7, with the nanocrystal radius decreasing from 3.6 to 1.6 nm.