Study of lattice dynamics via extended x-ray absorption fine structure

EXAFS (extended x-ray absorption fine structure), besides being a powerful structural probe, can also give original information on local dynamics in s olids. EXAFS is peculiarly sensitive to the correlation of vibrational moti on, both parallel and perpendicular to the bond direction, and to anharmoni city. This paper contains an introduction to the effects of thermal disorde r on EXAFS of crystals and to the data analysis based on the cumulant expan sion. Cumulants are easily connected to average local vibrational propertie s. Recently obtained experimental results concerning the mean square relati ve displacement and the thermal expansion in crystals confirm the potential ities of EXAFS as a dynamical probe.