Shaping light in 3D for direct asymmetric photochemistry: a 1000-fold enantioselectivity enhancement.

Shaping electronic motion with tailored light enables unprecedented control over matter: from realising topological states in quantum materials to steering chemical reactions along specific pathways. Yet, despite the vital roles of molecular chirality across nature, standard chiral light can barely influence the handedness of a chemical reaction, which is determined by the three-dimensional geometry of reactants and catalysts. Here we show how, by twisting light's Lissajous figure into a three-dimensional chiral structure, we can selectively excite one molecular enantiomer over its mirror image to trigger direct asymmetric photochemistry with an unprecedented degree of enantioselectivity. Our ab-initio simulations reveal ~30% enantioselectivity in the electronic excitation of the chiral molecule carvone-a three-orders-of-magnitude enhancement over current optical methods using circularly polarised light (~0.01%). Such control over the primary step of a photochemical reaction opens up a highly efficient route for manipulating molecular chirality exclusively with light. Thus, circumventing the current need for chiral catalysts or enantiopure reactants, and bringing direct asymmetric photochemistry into the realm of applications.