MFX Science Goals

X-ray diffraction has long been used to determine atomic structures of biomolecules. Unfortunately, the same X-rays that are used to probe the structure of the sample also get absorbed and deposit energy in the sample, causing irreparable damage. This often limits the resolution achievable in a particular sample, especially biological samples which are particularly sensitive to damage. X-ray crystallography has been very successful studying biological samples by spreading the damage over as many as billions of molecules in a single crystal, greatly enhancing the diffraction signal. Since the molecules are all identical and precisely aligned in the crystal, the X-ray scattering information is preserved and the structure can be determined. As crystals are reduced in size, they become more sensitive to damage due to the need to irradiate every molecule with more X-rays to get a measurable signal, causing more damage for each molecule.

LCLS offers a way around the damage problem. Since X-ray pulses from LCLS are very intense and very short, it is possible to deliver a higher dose to a sample and record the scattered X-ray information before the damage processes have time to destroy the sample. In other words, an LCLS X-ray pulse can be focused onto a sample, which gets destroyed—but not before the scattered X-rays are already on their way to the detector carrying the information needed to deduce the structure of the molecule. The Macromolecular Femtosecond Crystallography (MFX) instrument offers the possibility of determining structures at resolution beyond the damage limit for samples which are limited by radiation damage at synchrotron sources.

MFX provides a flexible suite of instrumentation for “diffract-before-destroy” studies in structural biology in an atmospheric pressure sample environment. The emphasis of the instrument lies in its multi-modal measurement capabilities, with the X-ray instrumentation being supplemented by additional tools such as  nanosecond and femtosecond pump laser systems as well as complementary optical measurement instrumentation.-As a result, MFX is a highly versatile instrument capable of a variety of scattering and spectroscopy techniques, serving several scientific fields such as  biology, soft-condensed matter, chemistry and soft condensed matter as well as material science and materials in extreme conditions.