Journal Article SFX X-ray diffraction serial crystallography Ferredoxins Metalloproteins Research Support, Non-U.S. Gov't Research Support, U.S. Gov't, Non-P.H.S. X-ray free-electron lasers XFELs aerosols aperture background scattering coherent diffractive imaging computer programs data processing electron diffraction free-electron laser laser–matter interaction materials science metalloprotein nanocrystals phase identification polymorphism protein crystallography radiation damage serial femtosecond crystallography signal-to-noise ratio single-particle imaging structural biology