CFEL, DESY 1 article published in JoVE Engineering Spatial Separation of Molecular Conformers and Clusters Daniel Horke1, Sebastian Trippel1, Yuan-Pin Chang1, Stephan Stern1,2, Terry Mullins1, Thomas Kierspel1,3, Jochen Küpper1,2,3 1Center for Free-Electron Laser Science, CFEL, DESY, 2Department of Physics, University of Hamburg, 3The Hamburg Center for Ultrafast Imaging, University of Hamburg We present a technique that allows the spatial separation of different conformers or clusters present in a molecular beam. An electrostatic deflector is used to separate species by their mass-to-dipole moment ratio, leading to the production of gas-phase ensembles of a single conformer or cluster stoichiometry.