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Physical Society Colloquium
Mark Sutton
Department of Physics Speckle is a graininess seen in the intensity of scattered light when using coherent light to illuminate a sample containing disorder. It depends on using coherent light and is not seen for conventional incoherent illumination. If the disorder of the material changes with time then the speckle pattern fluctuates and measuring these intensity fluctuations leads to a technique called intensity fluctuation spectroscopy (IFS). IFS is an ideal way to study the thermodynamic fluctuations in a system provided that the scattering intensity is sufficient for the time scales of the system under study. For the last three decades or so, it has been extensively used with light scattering to study a large variety of systems. Recently, the technique has been extended into the x-ray region where it has the advantage of accessing opaque materials, probing shorter length scales and providing a more direct interpretation of the results. The prime disadvantage of x-rays over visible light is the much lower intensity levels of coherent x-ray beams. In this talk, I will describe the basis of the technique and present recent results.
Friday, October 12th 2001, 15:30 |