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We present a micro-Raman study on the hydration and carbonation of the main silicate phases of Portland cement, i.e. monoclinic dicalcium silicate (C 2 S) and monoclinic tricalcium silicate (C 3 S). We investigate the reaction products and the loss of crystallinity induced by hydration on these two compounds. In the CO 2 -contaminated pastes we find that calcite, aragonite, and vaterite are inhomogeneously formed. We study sample cross sections to evaluate the maximum depth at which CaCO 3 is formed. We find that carbonation is limited to the first 500-1000 µm from the surface in the C 3 S pastes, while in C 2 S pastes CaCO 3 is formed well beyond this depth. Our results show the great potential of Raman spectroscopy in the study of the chemistry of cements.

We have studied LO phonon-plasmon coupled modes by means of Raman scattering in n-InP for carrier densities between 6ϫ10 16 and 1ϫ10 19 cm Ϫ3 . A line-shape theory based on the Lindhard-Mermin dielectric function that takes into account the nonparabolicity of the InP conduction band as well as temperature and finite wave-vector effects is used to fit the Raman spectra and extract accurate values of the electron density. The results obtained from the Lindhard-Mermin model are compared with the charge density determinations based on the Drude and the hydrodynamical models, and the approximations involved in these models are discussed. ͓S0163-1829͑99͒10431-4͔