Figure 19.

(a) Nanoparticles can enhance molecular circular dichrosim (CD) spectroscopy. A 75 nm radius silicon nanosphere is illuminated from below by λ = 625 nm circularly polarized light. The figure depicts the CD enhancement factor at a plane crossing the center of sphere. (b) When Kuhn’s dissymmetry factor is increased in the vicinity of a nanoparticle, the enantiomeric excess achievable in a photochemical reaction increases dramatically for a given extent of reaction. (Inset) Spatial distribution of dissymmetry factor enhancement for a 536 nm Si sphere at λ = 1391.82 nm. In the presence of a Si nanosphere, in a region where g ≈ 7, a 20% enantiomeric excess can be reached with a yield of 50% compared to the 1% achievable in the absence of the nanoparticle. Panel (a) adapted with permission from ref (205). Copyright 2013 American Physical Society. Panel (b) adapted with permission from ref (204). Copyright 2017 American Chemical Society.