Calendar of Events
X-ray lasers – a tool for discovery from extreme thermodynamics to biology
Speaker: Claudiu A. Stan (Rutgers University - Newark)
X-ray free-electron laser facilities (XFELs) are the most advanced type of X-ray sources, producing femtosecond X-ray pulses with sufficient energy to acquire data from samples in a single shot. With pulse durations a thousand times shorter than those available at synchrotron facilities, XFELs obviously extend the phase space available for X-ray dynamic studies by three orders of magnitude. However, their potential for enabling scientific discoveries extends to processes with a time scale of seconds because they can collect practically instantaneous single-shot data. I will exemplify this potential by briefly reviewing shock compression studies measuring nanosecond dynamics, and a broad effort to determine the microsecond-to-millisecond chemical mechanism of oxygen evolution in photosynthesis. Our research lies at the intersection of these distinct fields of research, and represents one of the first applications of XFELs to drive, rather than probe, dynamics in a condensed phase. In an initial investigation of the interaction between XFEL pulses and liquid microjets, which occurs routinely during protein crystallography studies, we discovered that XFEL ablation leads to unique shock wave and explosion dynamics. In a different study, using XFEL-induced shocks in water drops, we generated the largest metastable tensions in liquid water (< -100 MPa) reported yet for an unconfined system. Subsequent investigations of the shocks launched by XFELs in liquid jets revealed they have a surprisingly rich physics, exhibiting unique cavitation phenomena, and realizing a system where a maximal intensity sound is generated, with sound pressure levels above 270 dB in water. We also discovered that these shocks damage protein crystals by either disrupting their crystalline order or by inducing a remanent deformation in the protein structure.
Host: Valery Kiryukhin