AUTHOR=Hoffman David J. , Van Driel Tim B. , Kroll Thomas , Crissman Christopher J. , Ryland Elizabeth S. , Nelson Kacie J. , Cordones Amy A. , Koralek Jake D. , DePonte Daniel P. TITLE=Microfluidic liquid sheets as large-area targets for high repetition XFELs JOURNAL=Frontiers in Molecular Biosciences VOLUME=9 YEAR=2022 URL=https://www.frontiersin.org/journals/molecular-biosciences/articles/10.3389/fmolb.2022.1048932 DOI=10.3389/fmolb.2022.1048932 ISSN=2296-889X ABSTRACT=

The high intensity of X-ray free electron lasers (XFELs) can damage solution-phase samples on every scale, ranging from the molecular or electronic structure of a sample to the macroscopic structure of a liquid microjet. By using a large surface area liquid sheet microjet as a sample target instead of a standard cylindrical microjet, the incident X-ray spot size can be increased such that the incident intensity falls below the damage threshold. This capability is becoming particularly important for high repetition rate XFELs, where destroying a target with each pulse would require prohibitively large volumes of sample. We present here a study of microfluidic liquid sheet dimensions as a function of liquid flow rate. Sheet lengths, widths and thickness gradients are shown for three styles of nozzles fabricated from isotropically etched glass. In-vacuum operation and sample recirculation using these nozzles is demonstrated. The effects of intense XFEL pulses on the structure of a liquid sheet are also briefly examined.