Engineered SERS substrates employing nanoparticle cluster arrays with multiscale signal enhancement

摘要

Defined nanoparticle cluster arrays (NCAs) with total lateral dimensions of up to 25.4 μm by 25.4 μm have been fabricated on top of a 10 nm thin gold film using template guided self-assembly. This approach provides precise control of the structural parameters in the arrays allowing a systematic variation of the average number of nanoparticles in the clusters (n) and the edge to edge separation (Λ) between 1

主权项

1. A method of making a substrate for use in surface-enhanced Raman spectroscopy, comprising:
forming a planar substrate layer; and using a template-guided chemical self-assembly process to create a nanoparticle cluster array of defined size with nanoscale inter-particle separations at predefined pattern locations on the planar substrate layer, the template-guided chemical self-assembly process including:
forming a template on the planar substrate layer, the template defining an array of binding sites for respective nanoparticle clusters of the nanoparticle cluster array, the template further defining a deterministic binding site width D and a cluster separation Λ, Λ being a deterministic distance between adjacent nanoparticle clusters;depositing nanoparticles with selective binding at the binding sites through the template, a nominal number n of tightly-packed nanoparticles being deposited at each binding site based on a nominal size of the nanoparticles and the deterministic binding site width D; andsubsequently removing the template from the planar substrate layer, and further including the steps, performed prior to depositing the nanoparticles, of:
functionalizing the substrate layer with a first monolayer that becomes positively charged under buffer conditions existing when the nanoparticles are deposited; andpassivating the nanoparticles with a second monolayer that readily binds to the positively charged first monolayer at the binding sites when the nanoparticles are deposited.