Ultrafast self-gating Bragg diffraction of exploding nanocrystals in an X-ray laser

Area of Science:

• Structural biology
• Ultrafast X-ray science

Background:

• Intense femtosecond X-ray lasers are crucial for determining the structure of crystalline proteins.
• Damage processes during X-ray exposure can lead to loss of structural coherence, limiting imaging resolution and time scales.

Purpose of the Study:

• To investigate the nonthermal damage dynamics in crystalline proteins exposed to femtosecond X-ray lasers.
• To understand how ionization and atomic displacement affect Bragg diffraction and ultrafast imaging.

Main Methods:

• Utilizing a nonthermal description for damage dynamics.
• Calculating ultrafast ionization and subsequent atomic displacement.
• Analyzing the intensity and resolution dependence of diffraction degradation.

Main Results:

• Damage processes degrade Bragg diffraction on femtosecond time scales, gating ultrafast imaging.
• At high intensities, ionization affects low-resolution information first.
• At lower intensities, atomic displacement impacts high-resolution information.

Conclusions:

• Pulse length is not a limiting factor for X-ray imaging if X-ray flux is sufficient.
• Understanding damage mechanisms is key to optimizing ultrafast protein structure determination.