MFX Overview

MFX Full Name

​Macromolecular Femtosecond Crystallography

Short Description

The Macromolecular Femtosecond Crystallography (MFX) instrument makes use of the unique brilliant hard X-ray pulses from LCLS to perform a wide variety of experiments utilizing various techniques. The primary capability of MFX is to make use of the high peak power of the focused X-ray beam using the “diffraction-before-destruction” method. This technique prevents damage to a sample during the measurement by performing the measurement faster than the propagation of damage or destruction with ultrashort pulses. This is particularly advantageous for biological samples that suffer from electronic and structural damage during long continuous exposures to X-rays. The MFX instrument builds on the well-developed crystallographic techniques from synchrotrons and from the early days of LCLS to provide an atmospheric pressure, dedicated yet versatile instrument for multi-modal crystallographic measurements at LCLS.

MFX consists of a flexible instrumentation suite to make use of hard X-rays primarily in an atmospheric pressure environment. It enables femtosecond crystallography measurements capable of determining the structure of crystallized biomolecules at room temperature. Other techniques can provide complementary information for a more holistic understanding of molecular processes, such as X-ray Emission Spectroscopy, back-scattering, small and wide angle scattering. 

Plans exist for a flexible pump laser system for time-resolved experiments in the femtosecond time scale. MFX will be available for any scientific field requiring use of the LCLS beam, including structural biology, material science, materials in extreme conditions, atomic molecular and optical physics, chemistry and soft condensed matter, provided MFX is deemed most suitable for a particular science case. Samples can be introduced to the X-ray beam either fixed on targets using a high speed and high precision goniometer or using liquid jet systems that can deliver samples to the beam. Beryllium compound refractive lenses will be used for focusing the X-ray beam and control the spot size at the sample. The MFX instrument will operate primarily in the 5-20 keV range with the lower limit set by the atmospheric pressure operation and the upper limit eventually set by the capabilities of LCLS-II.

Scientific 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.