The effect of hyperenhancement of Raman scattering (RS) appearing on microcracks of the metal deposition (silver and gold) of uniaxially stretched polymer track-etched membranes is investigated. Deformation of membranes with a combination of high surface density and small diameter of their pores leads to the development of many microcracks in the metal coating. The efficiency of the surface enhancement RS (SERS) of the synthesized metasurfaces has been investigated on the example of organic compound malachite green, and the possibility to recognize extremely low fractions of the substance was demonstrated. An increase in the SERS signal with an increase in the deformation of the samples and even greater enhancement after their unloading and relaxation were found. The experiment on tensile strain and relaxation of the deformation of the samples and the consequent change in their electrical conductivity confirm the assumption that SERS appears on microcracks edges with a rather small distance between their boundaries. The SERS technique is proposed to analyze the formation of micro- and nanocracks on metal coatings.
Behavior of metallic nano-coating of the track membrane based on polyethylene terephthalate film under tension was investigated. In the vicinity of cracks in the coating, conical-shaped debondings of the coatings were observed. Debondings have the form of sharp cones, elongated along the tension axis and perpendicular to the cracks. Nanopores initiate multiple cracking of the coating, and the cracks initiate local debondings. Short microcracks mutually suppress their growth. As a result, long cracks crossing the entire coating do not appear. As a result, the coating retains its continuity and conducts electric current.
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