Absolute configuration refers to the spatial arrangement of atoms within a chiral molecule, giving you a stereochemical description of each chiral center. Assignment of absolute configuration is possible using MicroED through relative configuration or dynamical refinement.
Stereochemistry assignment for chiral molecules is possible using MicroED.
MicroED, like all crystallographic techniques, can easily assign the absolute configuration for racemic crystal forms, identifying both enantiomers with confidence. For enantiopure chiral samples, MicroED will narrow down the configuration to two possible stereoisomers, regardless of the number of chiral centers. Only one of these configurations is correct. Selection of the correct configuration can be done relative to a known chiral center or using dynamical refinement.
NIS is currently working to license the software PETS2 and Jana to provide absolute configuration information directly from the measured data using dynamical refinement. Keep a lookout for updates.