Branched Submicron Channels in Ultra-Thin Ag Films as Promise for High-Sensitivity, Time-Stable and Fast SERS-Based Molecular Sensing

ROA DÍAZ, SIMÓN; CORTÉS BURGOS, MARÍA JOSÉ; PEDANO, MARÍA LAURA*

Bahía Blanca

Encuentro; XII Encuentro De Superficies Y Materiales Nanoestructurados (NANO 2023); 2023

INQUISUR. UNS

Even to this day, noble metal-based nanostructures are still actively studied due to their promising prospects for the fabrication of efficient substrates for Surface Enhanced Raman Spectroscopy (SERS)-based molecular sensing [1, 2]. In this work, we report for the first time the gross potential of SERS substrates based on branched submicron channels in ultra-thin Ag films. Ag thin films were fabricated by magnetron sputtering and then annealed in high vacuum conditions to induce the growth of branched channels by thermal dewetting. Different sets of nominally equal samples were tested during a determined period using confocal Raman spectroscopy and methylene blue (MB, Raman-active molecule) to assess their performance for SERS in ambient aging conditions. Micro-Raman intensity mapping studies demonstrated the emergence of Raman signal enhancement “hot spots” in the branched submicron channels. A high mass sensitivity and fast spectral acquisition were achieved using these nanostructures, observing an exceptional spectral resolution in samples with a MB surface mass density of about 2 [ng/mm2] in a few seconds. A reasonably good spectral resolution was achieved even using shorter measurement times from 0.05 to 1 second, suggesting the potential for fast SERS analysis. Samples showed good reproducibility in the Raman spectral response during the test period, demonstrating the marginal impact of the aging effects on the Raman signal enhancement and ensuring a time-stable SERS performance in the short and long term. Our results show the proposed nanostructures are promising candidates for the design of high-sensitivity, time-stable, and fast SERS substrates, representing a simple and attractive alternative for efficient SERS-based molecular sensing.Figure 1REFERENCES1. W. Zhang, T. Zheng, B. Ai, P. Gu, Y. Guan, Y. Wang, Z. Zhao, G. Zhang, Applied Surface Science 593 (2022) 153388. 2. P. Mandal, B. S. Tewari, Surfaces and Interfaces 28 (2022) 101655.