8th Liquid Matter Conference September 6-10, 2011 Wien, Austria ...

Thu 811:10-14:00P8.7From liquid to glass : the evolution of the boson peakand the susceptibility during a chemical vitrificationprocessSilvia Caponi, 1 Silvia Corezzi, 2 Daniele Fioretto, 2 Aldo Fontana, 1 Giulio Monaco, 3and Flavio Rossi 11 IOM-CNR Dip. di Fisica di Trento, via Sommarive Povo, 38100, Trento, Italy2 Dip. di Fisica Università di Perugia, Perugia, Italy3 ESRF, Grenoble, FranceRaman-scattering measurements are used to follow the modification of the vibrational densityof states in a reactive epoxy-amine mixture during isothermal polymerization. Combining themwith Brillouin light and inelastic x-ray scattering measurements, we analyze the variations of theboson peak and of the Debye level while the system changes from liquid to glass upon increasingthe number of covalent bonds among the constituent molecules [1, 2]. The shift and intensityvariation of the boson peak are explained by the modification of the elastic properties throughoutthe reaction, and a master curve for the boson peak can therefore be obtained. Surprisingly,bond-induced modifications of the structure do not affect this master curve [2]. Moreover thecombined use of interferometric and dispersive depolarized light scattering (DLS) devices allow usto follow the evolution of the susceptibility spectrum during the polymerization process in a widefrequency range. The clear correlation between the modifications of the dynamic susceptibility ata given frequency and the phonons attenuation at the same frequency has been analyzed from theliquid to the glassy phase.[1] S. Caponi S. Corezzi, D. Fioretto, G. Monaco, A. Fontana, F. Rossi, Phys. Rev. Lett.102, 027402 (2009).[2] D. Fioretto S. Corezzi, S. Caponi, F. Scarponi, G. Monaco, A. Fontana, L. Palmieri, J. Chem.Phys. 128, 214502 (2008).7