J Synchrotron Radiat. 2013 Mar;20:332-8. doi: 10.1107/S0909049512051825. Epub 2013 Feb 01.

X-ray speckle visibility spectroscopy in the single-photon limit.

Journal of synchrotron radiation

Curt DeCaro, Vidanage Nuwan Karunaratne, Sambhunath Bera, Laurence B Lurio, Alec R Sandy, Suresh Narayanan, Mark Sutton, John Winans, Kirk Duffin, Jon Lehuta, Nicholas Karonis

PMID: 23412491 DOI: 10.1107/S0909049512051825

Abstract

The technique of speckle visibility spectroscopy has been employed for the measurement of dynamics using coherent X-ray scattering. It is shown that the X-ray contrast within a single exposure can be related to the relaxation time of the intermediate scattering function, and this methodology is applied to the diffusion of 72 nm-radius latex spheres in glycerol. Data were collected with exposure times as short as 2 ms by employing a resonant shutter. The weak scattering present for short exposures necessitated an analysis formalism based on the spatial correlation function of individual photon charge droplets on an area detector, rather than the usual methods employed for intensity correlations. It is demonstrated that this method gives good agreement between theory and experiment and thus holds promise for extending area-detector-based coherent scattering methods to the study of faster dynamics than previously obtainable.

Keywords: XPCS; droplet analysis; dynamics; speckle visibility

Publication Types

• Journal Article
• Research Support, U.S. Gov't, Non-P.H.S.