High performance SERS platforms via parametric optimization of the laser-assisted photodeposition of silver and gold nanoparticles

Abstract

Parametric optimization of the laser-assisted photocatalytic growth of Ag and Au nanoparticles for high SERS enhancement factor performance informed by design of experiment is demonstrated. The photodeposition process was divided into two phases –seeding and growth– in order to achieve the highest possible nanoparticle surface coverage for the size range from 10 to 100 nm. A substantial difference in the parameter effects between the Ag and Au seeding and growth was found. The SERS performance of the photodeposited Ag and Au nanostructures was evaluated at 532, 633 and 785 nm with thiophenol as a probe molecule. A high-enhancement broadband SERS operation was attained with Ag nanostructure grown at high laser fluences. The SERS enhancement factors of 105 were achieved with both Ag and Au nanostructures.

Reporting SERS enhancement factor: molecular surface coverage standards by grazing-incidence X-ray fluorescence.

“…Underestimating (overestimating) NSERS hinders the realistic evaluation of the EF resulting in exceedingly large (low) values and impeding comparability and reproducibility, as we discussed in previous work [9]. One-to-one comparison is made possible if the same molecule and surface density are used in the evaluation of NSERS [10,11]. However, there is no common practice in the evaluation of the substrate performance and, as stressed by a recent editorial [12], selecting standard analytes would be a relevant contribution of metrology to support the standardization process.…”