Shear-induced ordering in liquid microjets seen by x-ray cross correlation analysis.

V Markmann,L Frenzel,G Grübel,J Valerio,F Westermeier,M Dartsch,F Lehmkühler,M Walther,I Lokteva

doi:10.1063/4.0000038

Abstract

We applied shear to a silica nanoparticle dispersion in a microfluidic jet device and observed direction-dependent structure along and across the flow direction. The asymmetries of the diffraction patterns were evaluated by x-ray cross correlation analysis. For different Rayleigh nozzle sizes and shapes, we measured the decay of the shear-induced ordering after the cessation of the shear. At large tube sizes and small shear rates, the characteristic times of the decay become longer, but Péclet-weighted times do not scale linearly with Péclet numbers. By modeling particle distributions with the corresponding diffraction patterns and comparing measured shape asymmetry to simulations, we determined the variation of volume fraction over the azimuthal angle for the maximum ordered state in the jet.

Highlights

The control of a complex liquid sample system by microfluidic jet devices has become of increasing scientific and technological interest in the last few decades, especially at Free Electron Laser (FEL) facilities.1–5 The applications include the production of supercooled liquids by evaporative cooling of lm-sized droplets6–8 and sample delivery schemes for materials sensitive to radiation damage.9–11 Free flowing jets as sample environment have the advantage of a selfrefreshing sample and lack of solid boundaries, but low sample volumes often dictate small flow rates and, lm-thin jets
The asymmetries of the diffraction patterns were evaluated by x-ray cross correlation analysis
Higher shear typically leads to more pronounced structure development16,17 and, has to be taken into consideration for time-dependent and complex samples such as biological molecules that are measured in the flow of a liquid jet

Summary

Introduction

The control of a complex liquid sample system by microfluidic jet devices has become of increasing scientific and technological interest in the last few decades, especially at Free Electron Laser (FEL) facilities. The applications include the production of supercooled liquids by evaporative cooling of lm-sized droplets and sample delivery schemes for materials sensitive to radiation damage. Free flowing jets as sample environment have the advantage of a selfrefreshing sample and lack of solid boundaries, but low sample volumes often dictate small flow rates and, lm-thin jets. The control of a complex liquid sample system by microfluidic jet devices has become of increasing scientific and technological interest in the last few decades, especially at Free Electron Laser (FEL) facilities.. Free flowing jets as sample environment have the advantage of a selfrefreshing sample and lack of solid boundaries, but low sample volumes often dictate small flow rates and, lm-thin jets. Higher shear typically leads to more pronounced structure development and, has to be taken into consideration for time-dependent and complex samples such as biological molecules that are measured in the flow of a liquid jet. In ultrathin liquid sheets or flat-jets, infrared and soft x-ray spectroscopy becomes possible despite the strong absorption in this regime, but the small number of molecules in thin jets is especially susceptible to shear-induced alterations in the concentration distribution The onset of structure formation may influence the measured signal. In ultrathin liquid sheets or flat-jets, infrared and soft x-ray spectroscopy becomes possible despite the strong absorption in this regime, but the small number of molecules in thin jets is especially susceptible to shear-induced alterations in the concentration distribution

Methods

Results

Conclusion