X-ray photon correlation spectroscopy

The new field of x-ray photon correlation spectroscopy (XPCS) offers an unprecedented opportunity to extend the range of length scales over which a material's low frequency dynamics can be studied down to interatomic spacings. The ctitical decelopment which has now made EPCS a feasible technique is the high brightness of insertion devices at second and third generation synchrotron sources. In this talk, I will describe the principles of the XPCS technique and how it is practiced, as well as its potential use for a variety of important problems in the low frequency dynamics of condensed matter systems, such as complex fluids, glasses, surfaces and metallic alloys. Illustrations will be drawn from our recent results on using XPCS to study the Brownian motion of a gold colloid as well as recent results of others.