Atmospheric-Pulsed Laser Deposition of Dry Plasmonic Aerosols onto Laser-Textured Oxide-glass and Si for Enhanced SERS Detection

Abstract Developing sensitive, reproducible, and scalable SERS substrates using simple fabrication methods under ambient, chemical- and vacuum-free conditions remains a pressing research problem, particularly for low-cost and resource-limited applications. This paper investigates SERS substrates prepared through the atmospheric-PLD of plasmonic dry aerosols, formed by the heterogeneous condensation of the laser ablation material in flowing argon gas. The developed SERS substrates exploit the synergistic effects of plasmonic Ag or Au dry aerosols, laser-textured amorphous oxide glass and crystalline Si substrates, and laser-induced wettability modulation. Nanoparticle aerosols were generated by ns laser ablation (1064 nm, 10 ns, 30 Hz, and 3 ̶ 5 J cm−2), while substrate texturing was performed independently under a fixed condition (1064 nm, 30 ns, 33 mJ) using two laser shots per site at the fixed focal position. The morphology, composition, optical response and wettability of the substrates were systematically characterized using FE-SEM, EDX, UV−Vis absorption spectroscopy, and contact-angle measurements. SERS performance was studied and quantified for Rhodamine 6G (10−4 M) under 532 and 785 nm excitation. All substrates exhibited well-resolved Raman signatures with markedly higher intensities than conventional Raman measurements. The highest performance was achieved on laser-textured Si at an optimal aerosol-generation fluence of 4 J cm−2 under a fixed texturing condition, yielding an AEF of ∼1.1 × 103 and a SNR of ∼150. At 4 J cm−2, the optimal combination of NP coverage, interparticle spacing, and morphology resulted in the strongest SERS response. In addition, crystalline Si functionalized with Au and Ag aerosols consistently outperformed amorphous oxide glass counterparts. These results demonstrate that laser-induced surface modification, wettability control, and dry-aerosol plasmonic hotspots act synergistically to enhance SERS performance. Together, these findings bring atmospheric PLD one step closer to the practical implementation for sensitive and reproducible SERS substrates.