ANOMALOUS FEATURES OF RESONANT HYPER-RAMAN SCATTERING IN CUBR QUANTUMDOTS - EVIDENCE OF EXCITON-PHONON-COUPLED STATES SIMILAR TO MOLECULES

A resonant hyper-Raman scattering signal has been successfully observe d in CuBr quantum dots of a weak-confinement regime. It is found that up to fifth-order LO-phonon scattering signals appear in a two-photon resonance with the lowest confined state of the Z(12), S exciton, and that the observed order N depends on the two-photon energy 2HBAR omega (i), for the excitation in such a way that it conforms to the equation N less than or equal to(2HBAR omega(i)-E(edge))/HBAR omega(LO), with HBAR(LO) and E(edge) being energies of the LO phonon and the absorptio n edge, respectively. The anomalous result observed indicates that cou pled states of the Wannier exciton and the LO phonon are rather good e lementary excitations in these dots.