Large natural circular dichroism in photoionization

Circular dichroism in the photoionization of nanometer-sized aerosol particles from the chiral amino acid tyrosine is investigated. The Kuhn anisotropy factor in photoionization reaches values of 10%. This value is twenty times larger than previous results. We show that it strongly depends on properties of the particles. The largest anisotropies are obtained for highly ordered particles. The enhancement can be explained by an exiton-coupling mechanism between neighbouring molecules geometrically fixed in the crystal lattice. Implications of this large effect in the context of the origin of biological homochirality and for the construction of a bioaerosol sensor are discussed.