Liquid sample delivery at European XFEL - New developments

One of the unique features of European XFEL is the high repetition rate of the X-ray pulses. Intra-train repetition rates of up to 4.5 MHz challenge the sample injection systems. The Sample Environment & Characterization (SEC) group of the European XFEL develops sample delivery systems for all scientific instruments and provides user support in sample preparation, characterization, and delivery. One branch of SEC is dedicated to injecting liquid samples, especially using nozzles fabricated with submicrometer precision 3D printers. Cylindrical microjets are the most commonly used sample injection systems in soft X-ray liquid spectroscopy. However, they suffer from several drawbacks. Their curved surface, for example, complicates determining the path length of X-rays in the sample. Here, we present novel 3D-printed nozzle designs to produce microscopic flat sheet jets with micrometer thickness and high stability, intending to make this technology more widely available to users. Additionally, this poster presents Drop-on-demand systems that offer an alternative sample injection technique for complex time-resolved serial femtosecond crystallography (SFX) experiments with reduced sample consumption by synchronizing sample injection to the XFEL pulse train, as demonstrated at SPB-SFX, FXE, and MID instruments of European XFEL.