Surface Reactions at Chiral Surfaces

We developed a new method to identify the chirality of desorbing molecules after surface reaction using velocity resolved imaging techniques. It relies on the photoelectron circular dichroism (PECD), which can be deduced from the photoelectron angular distribution after laser ionization with circularly polarized light.

We apply this technique in molecular beam surface reaction experiments at an ultra-high vacuum apparatus. See Figure. It allows us to study elementary steps of important surface reaction with enantiosensitive resolution.

Molecular beam surface science apparatus for dosing chiral molecules at surfaces. Molecular beams are generated in pulsed nozzles mounted in the source chamber. After passing skimmer and differentially pumped chamber, the molecular beams enter the surface chamber and impinge upon the surface. Two nozzles are available for dosing the surface with different molecules. Nozzle 1 is mounted parallel to the surface normal. The molecular beam originating from nozzle 2 is tilted with respect to the surface normal. Molecules are ionized by laser radiation and detected in a velocity map imaging (VMI) setup, which is mounted next to the sample holder. Charged particles are accelerated and focused by VMI electrodes and are recorded on microchannel plates (MCPs) and a phosphor screen after 20 cm flight distance.