We investigate the excitation energy dependence of Raman modes in the 600-1200 cm(-1) range. The main features are first, two lines around 860 and 1060 cm(-1) independent of the energy and second, energy-dependent couples of lines, each of them composed of one first-order mode and one substractive combination band. In each couple, the frequency of the lines is found to follow a linear, strong and opposite energy dependence.