Circular dichroism in photoelectrons from adsorbed chiral molecules

The study of chiral molecules on two dimension is important for an analysis of enantio-selectivity in heterogeneous catalysis aiming to measure and control various biochemical functions. Here we show that such molecules can be identified through circular dichroism in core level photoemission from the stereoisomers of 2,3-butanediol molecules adsorbed on Si(100) and tartaric acids on Cu(110), using circularly polarized x-rays. The dichroic signal changes sign with going from the (RA) to the (S,S) enantiomer; it is absent in the achiral (R,S) isomer, demonstrating that the dichroism is caused by the chiral molecular environment of the photoionized atoms. This observation demonstrates the possibility of determining molecular chirality in the adsorbed phase.