Light emission from gold nanoparticles under ultrafast near-infrared excitation: thermal emission, inelastic light scattering or multiphoton luminescence?
arXiv:1802.04578 · doi:10.1021/acs.nanolett.7b04266
Abstract
Gold nanoparticles emit broad-band upconverted luminescence upon irradiation with pulsed infrared laser radiation. Although the phenomenon is widely observed, considerable disagreement still exists concerning the underlying physics - most notably over the applicability of concepts such as multiphoton absorption, inelastic scattering, and interband and intraband electronic transitions. Here, we study single particles and small clusters of particles by employing a spectrally resolved power-law analysis of the irradiation-dependent emission as a sensitive probe of these physical models. Two regimes of emission are identified: at low irradiance levels of kW/cm2, the emission follows a well-defined integer-exponent power law suggestive of a multiphoton process. However, at higher irradiance levels of several kW/cm2, the nonlinearity exponent itself depends on the photon energy detected, a tell-tale signature of a radiating heated electron gas. We show that in this regime, the experiments are incompatible with both interband transitions and inelastic light scattering as the cause the luminescence, while they are compatible with the notion of luminescence linked to intraband transitions.
arXiv comment23 pages, 4 figures
References in corpus (4)
Cited by in corpus (4)
- Nonlinear photoluminescence in gold thin films
- Excitation and Relaxation of Nonthermal Electron Energy Distributions in Metals with Application to Gold
- Coherent Control of the Non-instantaneous Nonlinear Power-law Response in Resonant Nanostructures
- Determinant role of size-dependent electron relaxation processes in the nonlinear luminescence emission of resonantly excited gold nanorods