Optical Properties of Ag Nanoparticle Arrays: Near-Field Enhancement and Photo-Thermal Temperature Distribution

Abstract

The near-field and photo-thermal properties of nanostructures have always been the focus of attention due to their wide applications in nanomaterials. In this work, we numerically investigate the near-field and photo-thermal temperature distribution in a nanoparticle array when the scattering light field among particles is considered. ‘Hot spots’, which represent strong electric field enhancement, were analyzed at the difference of the particle size, particle spacing and the polarization direction of the incident light. Interestingly, it is found that the position of the ‘hot spots’ does not rotate with the polarization direction of the incident light and always remains in the particle gaps along the line between particle centers. Moreover, the near-field is independent of the polarization in some special areas, and the factor of near-field enhancement keeps constant in these spots when the illumination polarization varies. As for photo-induced heating, our results show that both the temperature of the structure center and maximum temperature increase linearly with the particle number of the array while decreasing with the increase in particle spacing. This work provides some theoretical considerations for the near-field manipulation and photo-thermal applications of nanoarrays.

Surface-Enhanced Raman Spectroscopy of Ammonium Nitrate Using Al Structures, Fabricated by Laser Processing of AlN Ceramic

“…Different mechanisms may contribute to such enhancement. In the case of metal nanostructures, the efficient excitation of plasmons results in a strong enhancement of the electric field intensity [32]. The effect can be enhanced dramatically when the system is composed of nanostructures separated by a nanosized gap.…”

“…In the case presented here regarding of ammonium nitrate, SERS efficiency was lower when the AlN was processed in air. Since the hot spots are mainly localized between nanoparticles, oxidation will induce an increase in the gap between the nanoparticles which leads to less efficient plasmon coupling and the decrease in the nearfield intensity [32]. The lower efficiency of the structure fabricated by ablation of Al plate could be explained by the absence of nanoparticles and nanoparticle clusters, which are the source of the hot spots with the highest field enhancement, as shown in Figure 10.…”

High-Precision Optical Excited Heaters Based on Au Nanoparticles and Water-Soluble Porphyrin

“…Gold (Au) nanoparticles (NPs) are extremely promising as heaters under optical excitation in the plasmon absorption band [1][2][3][4]. Moreover, depending on the morphology, the broad plasmon absorption band can be shifted to the red region of the spectrum, therefore various laser sources could be used for excitation [5,6].…”

Editorial for Special Issue “Plasmon Assisted Near-Field Manipulation and Photocatalysis”

“…As a plasmonic photocatalytic mechanism, the photothermal properties of nanomaterials have received widespread attention due to their broad applicative potential. The near-field and photo-thermal temperature distribution of a nanoparticle array was numerically investigated by considering the scattering light field among particles [8]. It has been determined that the position of the 'hot spots' does not rotate with the polarization direction of the incident light and always remains in the particle gaps along the line between the particle centers, which provides theoretical considerations for the near-field manipulation and photo-thermal applications of nanoarrays.…”