Toward single-molecule surface-enhanced Raman scattering with novel type of metasurfaces synthesized by crack-stretching of metallized track-etched membranes

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.