Resonance Raman scattering and optical absorption studies of CdSe microclusters at high pressure

Abstract

The pressure dependence of the HOMO–LUMO transition energy and the frequency of the longest wavelength longitudinal optical vibration of 45 Å diameter CdSe clusters in methanol–ethanol solution have been measured up to 50 Kbar. The LO mode shifts to higher frequency at a rate of 0.43 cm⁻¹/Kbar, which corresponds to a Grüneisen parameter of 1.1. The HOMO–LUMO transition shifts to higher energy at 4.5 meV/Kbar, yielding a deformation potential of 2.3 eV. 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.