Express formation and characterization of SERS-active substrate from a non-degradable Ag-Nb-N-O film

In this work, we propose an original approach for rapid and easy conversion of a thin Ag-Nb-N-O film into surface enhanced Raman scattering (SERS) active substrate. The initial Ag-Nb-N-O substrate has a long shelf life because silver particles are prevalently accumulated inside the film and possess resistivity to degradation. An activation of the substrate is carried out just before the SERS-measurements by a 15-second microwave heating the Ag-NbN-O film at 800 W, which facilitates immediate extrusion of internal silver to the surface. This leads to the formation of a dense array of Ag particles that show an improved SERS-activity. We compare SERS-activity of the initial and microwave-treated Ag-Nb-N-O films with that of a control substrate based on Ag nanoparticles grown on the SiO2 surface. Both initial and control substrates are aged in a moist air for 60 days before the SERSmeasurements. An intensity of the SERS-signal from 10-5 M 5,5 '-Dithiobis(2-nitrobenzoic acid) or DTNB on the activated Ag-Nb-N-O film is approx. 270 higher than that on the control Ag nanoparticles. The TEM and EDS studies of the initial Ag-Nb-N-O film prove its stability to sulfidization while the control Ag nanoparticles are found to bind to sulfur from the moist air.