Characterization of Liquid Transport in MicroCapillaries via X-Ray Photon Correlation Spectroscopy

X-ray photon correlation spectroscopy (XPCS), a novel x-ray scattering technique analogous to dynamic light scattering, enables probing the hydrodynamics of liquids on length scales ranging from microns to nanometers and time scales ranging from seconds to microseconds. The National Synchrotron Light Source II (NSLS-II) of Brookhaven National Laboratory (BNL), which started operating in 2015 as one of the world's most advanced synchrotrons can enable XPCS studies with unprecedented spatio-temporal resolution. This presentation will discuss ongoing work at the Coherent Hard X-ray Scattering (CHX) beamline of NSLS-II where XPCS techniques are employed to characterize flow velocity profiles and mass diffusivity in microcapillaries. A genetic algorithm is developed to determine local flow velocities and diffusion coefficients from the intensity autocorrelation function obtained from XPCS experiments. The developed XPCS techniques and analytical methods can provide new insights into the hydrodynamic and rheological behavior of liquids in micro/nanoscale confinement.