Microscopic glass slides

Microscopic glass slides in dimensions of 25 m × 75 m × 1 m from ThermoFisher Scientific (UK) were used as a substrate for desorption, RAIRS, and EIS experiments, respectively. Before the vacuum deposition of metals, the substrates were sonicated in propanol. After washing in sulfuric acid, rinsed thoroughly with a generous amount of deionized (18.2 Ω·cm², Mili-Q, Millipore, Burlington, MA, USA) water and dried down under a stream of nitrogen (99.99%). The metal films of chromium ± 3 nm and silver ± 120 nm were deposited by the magnetron sputtering using the PVD75 system (Kurt J. Lesker Co., Pittsburg, PA, USA) under the real-time quartz microbalance control. Sputtering parameters for 2-inch diameter metal targets were as follows: Cr-power 200 W, sputtering current 0.50 A at 4.5 mTorr argon pressure; Ag-power 120 W, sputtering current 0.26 A at 5.5 mTorr argon pressure. Before coating, the deposition chamber was evacuated to <10⁻⁶ mTorr to the residual pressure. Ultrahigh purity, scientific grade argon (AGA, Malmö, Sweden) was used for the plasma sputtering.