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Published on: September 22, 2017
Quantifying optical scattering losses in pump-probe serial femtosecond crystallography experiments
Thomas R M Barends1, Alexander Gorel1, Stanisław Niziński1
1Max Planck Institute for Medical Research, Jahnstraße 29, Heidelberg, 69120, Germany.
Iucrj
|July 16, 2026
Summary
High-viscosity jets scatter less light than previously thought in ultrafast pump-probe serial femtosecond crystallography (SFX) experiments. This means lower laser energy is needed for studying light-induced reactions in crystals.
Area of Science:
- Structural Biology
- Biophysics
- Spectroscopy
Background:
- Ultrafast pump-probe serial femtosecond crystallography (SFX) relies on high laser fluence to induce photoreactions.
- Previous assumptions suggested significant pump laser scattering by viscous jets, limiting crystal excitation.
- This assumption is debated, necessitating experimental verification of laser fluence delivery.
Purpose of the Study:
- To investigate pump laser scattering losses in high-viscosity jets for time-resolved SFX.
- To compare different sample delivery methods (high-viscosity extrusion and sheet-on-sheet) for laser fluence delivery.
- To determine the influence of delivery methods on light-induced reaction intermediate occupancies.
Main Methods:
- Performed time-resolved SFX experiments on fatty acid photodecarboxylase crystals.
- Utilized high-viscosity extrusion (HVE) and sheet-on-sheet (SOS) fixed-target sample delivery systems.
- Employed tightly focused pump laser beams to minimize light contamination in SOS chips.
Main Results:
- Optically transparent high-viscosity jets showed significantly less scattering than previously claimed.
- Photoproduct yields approached 70-80% for HVE and 60-70% for SOS, relative to computational predictions.
- Demonstrated that excessive photoexcitation energy densities are unnecessary for appropriately sized crystals in SFX.
Conclusions:
- High-viscosity jets and chip-based methods deliver pump laser fluence more efficiently than assumed.
- Accurate fluence delivery is crucial for optimizing time-resolved SFX experiments.
- Reduced laser energy requirements can be achieved, making experiments more accessible and efficient.
