Long-term plasmonic stability of copper nanoparticles produced by gas-phase aggregation method followed by UV-ozone treatment

Coinage metal nanoparticles (NPs) are well-known for the phenomenon of localized surface plasmon resonance (LSPR), which is widely utilized for enhanced sensing and detection. LSPR stability over time is an important issue for practical application of the nanoparticle matrixes. Some metals, and copper among those, are chemically reactive in ambient atmospheric condi-tions that leads to degradation of plasmonic functionality. This work reports on the formation of Cu NP matrixes utilizing magnetron-sputtering gas-phase aggregation, size-selection and soft-landing on a substrate. This method provides monocrystalline NPs with high purity, thus, improving chemical inertness towards ambient gases, for example, oxygen. Additionally, a simple approach of UV-ozone treatment was shown to form an oxide shell protecting the metal-lic core against reactions with environmental species and stabilizing the plasmonic properties for period over 150 days. Suggested methodology is promising to improve the competitiveness of Cu nano-matrices with those of Au and Ag in plasmonic sensing and detection.