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Free keywords:
serial synchrotron crystallography; SSX; picosecond infrared lasers; PIRL; fixed targets; sample delivery
Abstract:
In order to utilize the high repetition rates now available at X-ray free-electron
laser sources for serial crystallography, methods must be developed to softly
deliver large numbers of individual microcrystals at high repetition rates and
high speeds. Picosecond infrared laser (PIRL) pulses, operating under
desorption by impulsive vibrational excitation (DIVE) conditions, selectively
excite the OH vibrational stretch of water to directly propel the excited volume
at high speed with minimized heating effects, nucleation formation or cavitationinduced
shock waves, leaving the analytes intact and undamaged. The soft
nature and laser-based sampling flexibility provided by the technique make the
PIRL system an interesting crystal delivery approach for serial crystallography.
This paper demonstrates that protein crystals extracted directly from aqueous
buffer solution via PIRL-DIVE ablation retain their diffractive properties and
can be usefully exploited for structure determination at synchrotron sources.
The remaining steps to implement the technology for high-speed serial
femtosecond crystallography, such as single-crystal localization, high-speed
sampling and synchronization, are described. This proof-of-principle experiment
demonstrates the viability of a new laser-based high-speed crystal delivery
system without the need for liquid-jet injectors or fixed-target mounting
solutions.
