Abstract
The needs both for increased experimental throughput and for in operando characterization of functional materials under increasingly realistic experimental conditions have emerged as major challenges across the whole of crystallography. A novel measurement scheme that allows multiplexed simultaneous measurements from multiple nearby sample volumes is presented. This new approach enables better measurement statistics or direct probing of heterogeneous structure, dynamics or elemental composition. To illustrate, the submicrometer precision that optical lithography provides has been exploited to create a multiplexed form of ultra-small-angle scattering based X-ray photon correlation spectroscopy (USAXS-XPCS) using micro-slit arrays fabricated by photolithography. Multiplexed USAXS-XPCS is applied to follow the equilibrium dynamics of a simple colloidal suspension. While the dependence of the relaxation time on momentum transfer, and its relationship with the diffusion constant and the static structure factor, follow previous findings, this measurements-in-parallel approach reduces the statistical uncertainties of this photon-starved technique to below those associated with the instrument resolution. More importantly, we note the potential of the multiplexed scheme to elucidate the response of different components of a heterogeneous sample under identical experimental conditions in simultaneous measurements. In the context of the X-ray synchrotron community, this scheme is, in principle, applicable to all in-line synchrotron techniques. Indeed, it has the potential to open a new paradigm for in operando characterization of heterogeneous functional materials, a situation that will be even further enhanced by the ongoing development of multi-bend achromat storage ring designs as the next evolution of large-scale X-ray synchrotron facilities around the world.
Highlights
Across a wide range of current scattering-based materials research, across the whole of crystallography, the need for increased experimental throughput and for in operando characterization of functional materials under increasingly realistic experimental conditions have emerged as major challenges
We use an implementation of this multiplexing approach for ultra-small-angle X-ray scattering (USAXS) based X-ray photon correlation spectroscopy (XPCS) measurements as an example to illustrate the application and potential of such an arrangement
Using XPCS measurements of the equilibrium dynamics of a colloidal suspension as an example, we prove that, does such an array allow some of the challenges faced by XPCS measurements to be overcome, and that the multiplexed measurement configuration offers the additional potential to map out or image any spatial variations in the temporal correlations that exist within a sample at any one time
Summary
Across a wide range of current scattering-based materials research, across the whole of crystallography, the need for increased experimental throughput and for in operando characterization of functional materials under increasingly realistic experimental conditions have emerged as major challenges. We propose using microfabricated pinhole or slit arrays with submicrometer fabrication precision for producing multiple small X-ray probes, with individual pixels in a suitable area detector serving as independent detectors This multiplexing approach can allow multiple experiments to be performed in parallel, with the additional advantage of simultaneously probing numerous nearby regions of a single heterogeneous sample. One general yet critical aspect of an XPCS experiment is the coherent signalto-noise ratio (SNR); this tends to define the minimum counting time required to determine the temporal correlations of interest This issue is linked to another major challenge faced by XPCS, which is that beam damage often needs to be minimized for low-Z (soft matter) materials, whose intrinsic dynamic time scales would otherwise make them ideal systems to be investigated by XPCS. We conclude by offering our thoughts concerning the prospect of multiplexed measurements using slit arrays for both XPCS and other scattering, diffraction or spectroscopic techniques, those based at X-ray synchrotron facilities
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