Liquid Sample Delivery for Coherent Diffractive Imaging at X-ray Free-Electron Lasers

To gain knowledge about the functioning of the molecular machines of life, we apply serial crystallography 1 and diffractive imaging to investigate the structure and dynamics of bio macromolecules. Serial diffraction overcomes long standing limitations in X ray based structure determination caused by radiation damage. It combines partial or snapshot diffraction from tens of thousands (or even millions) of small crystals or particles, measured individually at low dose (at synchrotros ) or under the conditions of “diffraction before destruction” with XFEL pulses. This enables time resolved measurements of systems undergoing reactions at physiological temperatures. This approach crucially depends upon methods to rapidly replenish samples into the X ray beam, such as the use of free liquid jets . Gas dynamic virtual nozzles GDVNs ) use an outer stream of helium to compress the jet down to a few micrometer in diameter. 2 We develop these in combination with particle focusing/bunching capabilities and assisted by advanced computational fluid dynamics ( CFD ) simulations. Reproducible geometric features for reliable performance is achieved for a variety of experimental needs by using sub micrometer precision 3D printers. 3 Here, we present recent developments of GDVNs, mixing GDVNs, electrosprayers and electrojet devices that are tailored to meet our goals for time resolved SFX and single particle imaging (SPI) experiments 4 at XFELs and in particular to achieve high quality diffraction data from limited sample quantities.