Evolution of nonlinear optical properties: from gold atomic clusters to plasmonic nanocrystals.

摘要: Atomic clusters of metals are an emerging class extremely interesting materials occupying the intermediate size regime between atoms and nanoparticles. Here we report nonlinear optical (NLO) characteristics ultrasmall, atomically precise gold, which smaller than critical for electronic energy quantization (∼2 nm). Our studies reveal remarkable features distinct evolution nonlinearity as progress in from nonplasmonic to plasmonic regime. We ascertain that smallest atomic do not show saturable absorption at surface plasmon wavelength larger gold nanocrystals (>2 Consequently, third-order these ultrasmall exhibits a significantly lower threshold power limiting. This limiting efficiency, is superior nanocrystals, highly beneficial applications.