Imaging of femtosecond bond breaking and charge dynamics in ultracharged peptides.

X-ray free-electrons lasers have revolutionized the method of imaging biological macromolecules such as proteins, viruses and cells by opening the door to structural determination of both single particles and crystals at room temperature. By utilizing high intensity X-ray pulses on femtosecond timescales, the effects of radiation damage can be reduced. Achieving high resolution structures will likely require knowledge of how radiation damage affects the structure on an atomic scale, since the experimentally obtained electron densities will be reconstructed in the presence of radiation damage.

Ultrafast dynamics and scattering of protic ionic liquids induced by XFEL pulses.

X-rays are routinely used for structural studies through scattering, and femtosecond X-ray lasers can probe ultrafast dynamics. We aim to capture the femtosecond dynamics of liquid samples using simulations and deconstruct the interplay of ionization and atomic motion within the X-ray laser pulse. This deconstruction is resolution dependent, as ionization influences the low momentum transfers through changes in scattering form factors, while atomic motion has a greater effect at high momentum transfers through loss of coherence.

Femtosecond bond breaking and charge dynamics in ultracharged amino acids.

Historically, structure determination of nanocrystals, proteins, and macromolecules required the growth of high-quality crystals sufficiently large to diffract X-rays efficiently while withstanding radiation damage. The development of the X-ray free-electron laser has opened the path toward high resolution single particle imaging, and the extreme intensity of the X-rays ensures that enough diffraction statistics are collected before the sample is destroyed by radiation damage. Still, recovery of the structure is a challenge, in part due to the partial fragmentation of the sample during the diffraction event.