Single-molecule imaging with longer X-ray laser pulses.

Area of Science:

• Structural biology
• Biophysics
• X-ray science

Background:

• Serial femtosecond crystallography (SFX) determines protein structures using X-ray laser pulses.
• The "self-gating" effect allows SFX to succeed with longer pulses (50-100 fs) by limiting damage.

Purpose of the Study:

• To investigate if a similar "self-gating" effect applies to single-molecule diffraction.
• To assess the feasibility of sub-nanometer single-molecule imaging with current X-ray pulse durations.

Main Methods:

• Theoretical analysis of diffraction contrast in single-molecule imaging.
• Separating diffraction from the average structure and from damage-induced "damage noise".

Main Results:

• A "self-gating" effect, similar to SFX, is applicable to single-molecule diffraction.
• This effect suggests sub-nanometer imaging with 30-50 fs pulses is still achievable.
• Calculations highlight the impact of damage on diffraction contrast.

Conclusions:

• The "self-gating" phenomenon extends to single-molecule diffraction, broadening its applicability.
• Current X-ray pulse durations are potentially sufficient for high-resolution single-molecule imaging.
• New theoretical frameworks facilitate damage model testing and optimization of imaging conditions.