Structured electric-dipole-based chirality

Descrizione del progetto

Strutturare la luce per separare efficacemente molecole con manualità opposta

Distinguere e separare molecole con manualità opposta ha profonde implicazioni in chimica, biologia e nanotecnologia. La luce, seppur molto efficiente nel distinguere enantiomeri opposti, è molto inefficiente quando si tratta di separarli. Il progetto STREDCH, finanziato dall’UE, esplorerà un nuovo tipo di chiralità nella luce: la chiralità locale della luce o LLC. I ricercatori si propongono di sfruttare la LLC per dimostrare un trasferimento di popolazione enantioselettivo efficiente tra stati elettronici, nonché generare e strutturare la LLC utilizzando supporti e fasci di luce strutturati. Si prevede che le attività del progetto sfruttino il fatto che l’accoppiamento tra LLC e chiralità molecolare si basa solo su interazioni elettriche-dipolo, che sono ordini di grandezza più forti di quelle magnetiche-dipolo richieste dai metodi standard.

Obiettivo

Molecular chirality has profound as well as practical implications in chemistry, biology, and nanotechnology. While light is well established for distinguishing between opposite molecular enantiomers and there have been incredible advances in light sources, established methods for enantioselective synthesis and separation still rely on molecule-molecule interactions because the chirality of light couples only weakly to the chirality of molecules. This smallness stems from the dependence of this coupling on magnetic-dipole interactions. We recently found a new type of chirality in light – local chirality – which relies only on the electric field and is relevant for nonlinear light-matter interaction. Light’s local chirality (LLC) couples very strongly to molecular chirality – exclusively through electric-dipole interactions – as we already demonstrated distinguishing opposite enantiomers with perfect contrast [Nat.Phot.13,866(2019)]. Its immense potential in the fields of enantioselective synthesis and separation remains to be uncovered. The overall objective of this proposal is to set the cornerstones for realizing this potential.

The specific objectives of this proposal are (I) To use LLC to demonstrate efficient enantioselective population transfer between electronic states. (II) To use LLC to demonstrate ponderomotive-force-like enantioselective deflection of molecular beams. (III) To explore the generation and the structuring of LLC using structured media. (IV) To explore the generation of topologically non-trivial structures in LLC with the help of beams carrying orbital angular momentum and structured media.

Achieving these objectives will deliver the missing link needed to finally take advantage of our amazing control over light to synthesize and separate chiral molecules in an enantioselective fashion. It will bring efficiencies orders of magnitude better than previous magnetic-dipole-based methods and will have a direct impact on the chemical industry.