Sample delivery for serial crystallography at free-electron lasers and synchrotrons.

Marie Luise Grünbein,Gabriela Nass Kovacs

doi:10.1107/s205979831801567x

Abstract

The high peak brilliance and femtosecond pulse duration of X-ray free-electron lasers (XFELs) provide new scientific opportunities for experiments in physics, chemistry and biology. In structural biology, one of the major applications is serial femtosecond crystallography. The intense XFEL pulse results in the destruction of any exposed microcrystal, making serial data collection mandatory. This requires a high-throughput serial approach to sample delivery. To this end, a number of such sample-delivery techniques have been developed, some of which have been ported to synchrotron sources, where they allow convenient low-dose data collection at room temperature. Here, the current sample-delivery techniques used at XFEL and synchrotron sources are reviewed, with an emphasis on liquid injection and high-viscosity extrusion, including their application for time-resolved experiments. The challenges associated with sample delivery at megahertz repetition-rate XFELs are also outlined.

Highlights

The unprecedented properties of X-ray free-electron lasers (XFELs) enable novel research in a variety of scientific fields (Pellegrini, 2016)
The current sample-delivery techniques used at XFEL and synchrotron sources are reviewed, with an emphasis on liquid injection and high-viscosity extrusion, including their application for time-resolved experiments
At a relatively low irradiance (Grunbein, Bielecki et al, 2018; Wiedorn, Oberthur et al, 2018). Microcrystals suspended in their mother liquor or in a suitable carrier medium can be injected into the X-ray interaction region as a continuous jet or as droplets synchronized with the XFEL pulse

Summary

Introduction

The unprecedented properties of X-ray free-electron lasers (XFELs) enable novel research in a variety of scientific fields (Pellegrini, 2016). The challenge is lifted to a new level with the advent of XFEL sources operating at megahertz X-ray repetition rates, requiring much faster sample delivery, such as LCLS-II (Schoenlein, 2015) or the EuXFEL (Altarelli & Mancuso, 2014; Tschentscher et al, 2017), with the first results from the latter having recently been published (Grunbein, Bielecki et al, 2018; Wiedorn, Oberthur et al, 2018). Some of these sample-delivery techniques have been ported to synchrotrons, since in specific cases they can offer advantages over traditional synchrotron techniques. At a relatively low irradiance (Grunbein, Bielecki et al, 2018; Wiedorn, Oberthur et al, 2018)

Injection

Liquid injection

Fixed target for serial sample delivery

Conclusion and outlook