Facoltà di Ingegneria Civile e Industriale

Raman spectroscopy uses the light-matter interaction (scattering) to obtain information about the energetic states of the molecules. However, some molecular properties remain invisible to the traditional Raman effect, while they can be revealed using the Hyper-Raman effect: two photons hit simultaneously a molecule, and a single photon gets scattered with wavelength change. While the Hyper-Raman penetrates more deeply into the living tissues without damaging the molecules, this effect suffers of very low photon numbers. Thanks to the nanotechnology, the hyper-Raman efficiency can be boosted using metallic nanostructures in the vicinity of molecules. This study uses, for the first time, the Hyper-Raman effect to study a fundamental property of life: the chirality.

The research conducted by an international team, guided by professor Ventsislav Valev of the University of Bath, in collaboration with researcher Emilija Petronijevic Ph.D., RTDa from ICI-SBAI Sapienza, is published in the journal Nature Photonics. The study uses golden nanohelices, resonant at 1064 nm (illumination), to transfer the chirality to the achiral molecules, resonant at 532 nm (hyper-Raman). The nanohelices also work as nanoantennas to prevalently concentrate the electromagnetic field on molecules hence boosting the Hyper-Raman signal. The results confirm a 45 year old theory, and they could open new possibilities in applications regarding pharmaceutical science, forensic medicine and environmental science.

I risultati confermano una teoria vecchia 45 anni, e potrebbero aprire nuove possibilità in applicazioni quali la scienza farmaceutica, la medicina forense e le scienze ambientali. The collaboration and the researcher’s mobility was supported by the PON Research and Innovation project 2014-2020 “Low-cost nanophotonics for green and sustainable chiral sensing”.

More information:  https://doi.org/10.1038/s41566-024-01486-z