Optical properties of silver nanocrystals self-organized in a two-dimensional superlattice: Substrate effect

Abstract

Experimental and calculated reflectivity spectra of silver nanocrystals self-assembled in compact hexagonal networks on various substrates ͓highly oriented pyrolytic graphite ͑HOPG͒, gold, silicon, and Al 0.7 Ga 0.3 As] are compared. The calculated spectra are deduced from a model based on a mean-field theory and taking into account the electromagnetic resonances for p ͑parallel͒ and s ͑perpendicular͒ polarizations. From experimental and calculated spectra, it is concluded that the major change in the responses is due to the refractive index of the substrate. Hence, the optical properties of coated silver nanocrystals organized in a hexagonal network do not depend on the substrate used. That is to say no specific interactions between nanocrystals and substrate take place. Collective optical properties due to the formation of a film made of 5-nm silver nanocrystals are observed. This is pointed out by the appearance of an additional resonance at a higher energy than that of the plasmon resonance of isolated nanocrystals.

Influence of size, shape and core–shell interface on surface plasmon resonance in Ag and Ag@MgO nanoparticle films deposited on Si/SiOx

“…Plasmon-enhanced performance can also be achieved in organic solar cells by incorporating Ag NPs on surface-modified transparent electrodes [8], and in LEDs by increasing their external quantum efficiency [6]. On the other hand, a number of studies on the optical properties of noble metal NPs on different surfaces have been performed [10,11], revealing the drastic dependence of the SPR oscillator strength and energy position on the NP size [12][13][14], geometrical shape [14][15][16], surface density [15][16][17] and the type of substrate [18]. In most of these works, NPs were realized by metal evaporation on a substrate, where islands were formed by the Vollmer-Weber growth mode [15,16].…”

“…For this purpose, controlled co-deposition and systematic investigation of the NP structure, chemical composition and film morphology is crucial in order to obtain films of desired functional properties. Computation of optical spectra, which is necessary for the interpretation of the experimental data [16][17][18], also requires this detailed characterization information as input. In fact, electromagnetic modelling requires knowledge of the NP shape, size and arrangement of the NPs to provide results comparable with experiments.…”

Fluorescence properties of Ag nanoparticles in water, methanol and hexane

“…Besides their ability to promote surface enhanced optical phenomenon [5,6], it was discovered that noble metal clusters display intense visible fluorescence. A study of fluorescence emitted from these particles, yields new insight into their origin and new application possibilities [1,[7][8][9]. Fluorescence spectroscopy has proved as a very sensitive technique to study the fluorescence properties of nanoparticles.…”

Toward an ideal nanomaterial for on-chip Raman laser

“…[67][68][69] The physical properties of nanocrystals selforganized into compact arrays are quite di® erent from those of both isolated nanocrystals and the bulk phase. The collective optical [67][68][69][70] properties of these nanocrystal assemblies are governed mainly by dipolar interactions. In Ref.…”