Resonance Raman Scattering and Optical Absorption Studies of CdSe Microclusters at High Pressure.

The pressure dependence of the lowest exciton transition energy, and the frequency of the longest wavelength longitudinal optical vibration of 45angstroms diameter CdSe clusters in methanol- ethanol solution have been measured up to 50Kbar. The LO mode shifts to higher frequency at a rate of 0.43cm sup (-1) /Kbar, which corresponds to a Gruneisen parameter of 1.1. The exciton transition shifts to higher energy at 4.5meV/Kbar, yielding a deformation potential of 2.3eV. The pressure dependence of these properties closely resemble those of the corresponding bulk solid, confirming the point of view that the lattice properties of these clusters resemble those of the bulk, even though the optical properties are quite distinct due to quantum confinement.