Nonclassical optical properties of mesoscopic gold

Abstract

Gold nanostructures have important applications in nanoelectronics, nano-optics as well as in precision metrology due to their intriguing opto-electronic properties. These properties are governed by the bulk band structure but to some extend are tunable via geometrical resonances. Here we show that the band structure of gold itself exhibits significant size-dependent changes already for mesoscopic critical dimensions below 30 nm. To suppress the effects of geometrical resonances and grain boundaries, we prepared atomically flat ultrathin films of various thicknesses by utilizing large chemically grown single-crystalline gold platelets. We experimentally probe thickness-dependent changes of the band structure by means of two-photon photoluminescence and observe a surprising 100-fold increase of the nonlinear signal when the gold film thickness is reduced below 30 nm allowing us to optically resolve single-unit-cell steps. The effect is well explained by density functional calculations of the thickness-dependent 2D band structure of gold.

References in corpus (7)

• Mode-matching in multiresonant plasmonic nanoantennas for enhanced second harmonic generation
• Atomically flat single-crystalline gold nanostructures for plasmonic nanocircuitry
• Observation of intrinsic size effects in the optical response of individual gold nanoparticles
• Mode imaging and selection in strongly coupled nanoantennas
• Plasmons do not go that quantum
• Dynamics of four-photon photoluminescence in gold nanoantennas
• Single-crystalline gold microplates grown on substrates by solution-phase synthesis

Cited by in corpus (5)

• Extremely confined gap plasmon modes: when nonlocality matters
• Large-area, freestanding single-crystal gold of single nanometer thickness
• Quantum-mechanical effects in photoluminescence from thin crystalline gold films
• Anisotropic Second Harmonic Generation From Monocrystalline Gold Flakes
• Nonlinear photoluminescence in gold thin films