Fabrication of SERS-Active Patterned Gold Nanoparticle Films by Electron Irradiation and Postpyrolysis

Abstract

An approach to fabricate patterned gold (Au) nanoparticle (NP) films for surface-enhanced Raman scattering (SERS) active substrates is presented on the base of electron irradiation and subsequent pyrolysis of solid precursor films, which is a mixture of hydrogen tetrachloroaurate (HAuCl 4 ), ethylene glycol, and poly(diallyldimethyl ammonium chloride) (PDDA). Electron irradiation decomposed HAuCl 4 to form Au NP seeds and simultaneously induced cross-link of PDDA. Due to the cross-linking behavior of PDDA under electron irradiation, the precursor film could be patterned by selectively irradiating an electron beam onto the film using a metal mask. Subsequent pyrolysis process resulted in the growth of Au seeds while completely decomposing organic materials, leading to the formation of a patterned film comprising high-purity Au NPs. The size of the Au NPs could be readily controlled from 25 to 92 nm by changing the thickness of the precursor film. The prepared Au NP films exhibited NP size-correlated SERS enhancement factors and had the maximum enhancement factor of 6.6 × 10 5 for thiophenol.

Efficient electron-induced removal of oxalate ions and formation of copper nanoparticles from copper(II) oxalate precursor layers

“…However, the NPs are often formed with a wide size distribution, which partly relates to the fact that precursor preparation by drying solutions at a surface usually does not yield a layer with homogeneous thickness but rather aggregates of small crystallites [ 12 – 13 ]. In contrast, when polymer matrices deposited by spin-coating and containing ionic Au were irradiated [ 14 – 15 ], the NP size could be tuned by controlling the layer thickness [ 15 ]. Washing and pyrolysis of the molecular residues was then necessary to obtain pure metal NPs, the latter unfortunately inducing post-irradiation particle growth ascribed to Ostwald ripening and therefore deteriorating the monodispersity [ 15 ].…”

“…In contrast, when polymer matrices deposited by spin-coating and containing ionic Au were irradiated [ 14 – 15 ], the NP size could be tuned by controlling the layer thickness [ 15 ]. Washing and pyrolysis of the molecular residues was then necessary to obtain pure metal NPs, the latter unfortunately inducing post-irradiation particle growth ascribed to Ostwald ripening and therefore deteriorating the monodispersity [ 15 ]. As an alternative, a homogeneous precursor distribution on the surface was achieved by using liquid precursor materials, i.e., molten salts [ 5 ] or solutions of the precursors [ 6 – 8 ].…”

Detection and analysis of SERS effect of nano gold by self-assembly chemical plating composite method

“…The SSEF that takes into account the average SERS effect and the relationship between SERS effect and distance, has become the most widely used definition for SERS EF. Using SSEF, Yong Nam Kim [24] calculated EF values of patterned nano gold films that were fabricated by base of electron irradiation and subsequent pyrolysis of solid precursor films. The EF value was a maximum for NP film with the average particle size of 67 nm, and the maximum enhancement factor of 6.6 × 10 5 for thiophenol.…”

Gold Coated Zinc Oxide Nanonecklaces as a SERS Substrate

“…Larger particle size requires higher excitation wavelength to generate plasmon resonance. [24][25] We speculate ZnO NNs with size around 100 nm have much larger plasmon resonance under 785 nm laser excitation than the smaller gold NPs (∼10 nm), hence producing higher enhancement signals. As mentioned earlier, the Au coated ZnO NN could also be considered as a half or incomplete nanoshell structure.…”