Séminaire exceptionnel

Vendredi 2 décembre 2005 à 11h30
Tour 33, couloir 33-43, 2ème étage, salle de réunion

Matteo Pierno
(LCVN, Université Montpellier 2)

Direct Experimental Evidence of a Growing Lengthscale Escorting the Glass Transition

Understanding the glass formation is a challenge because the existence of a true glass state, distinct from liquid and solid, remains elusive: Glasses are liquids that have become too viscous to flow. An old idea is that the dynamics becomes sluggish when approaching the glass transition because increasingly larger regions of the material have to movesimultaneously to allow flow. We introduce new multi-point dynamical susceptibilities to estimate quantitatively the size of these regions,
and provide direct experimental evidence that the glass formation of molecular liquids and colloidal suspensions is escorted by growing dynamic correlation lengthscales. Finally we discuss some preliminar data on the ageing of concentrated colloidal hard-spheres.