Optical Activity in Third?Harmonic Rayleigh Scattering: A New Route for Measuring Chirality

In 3D isotropic liquids, optical third-harmonic generation is forbidden, with circularly polarized light (CPL). Yet the associated nonlinear susceptibility directly influences properties at fundamental frequency by intensity dependence (Kerr effect). Here, hidden upon CPL illumination are revealed demonstrating a new effect, in hyper-Rayleigh scattering. This effect succinctly enunciated: of scattered incident depends on chirality scatterers. It referred to as (hyper) Rayleigh scattering activity (THRS OA) and was observed from Ag nanohelices randomly dispersed water. The first analytical theory model for also provided, highlighting role localized transition dipoles along helical length. THRS OA remarkably user-friendly. offers access intricate (hyperpolarizabilities) that have so far been more easily accessible computation essential understanding light?matter interactions. could find applications hyper-sensitive characterization molecules nanostructures; this plays function bio/nano-machinery, promising next technologies.