Nano-Raman mapping of a porous glass-ceramic SERS substrate in collection mode

Porous glass-ceramics is an extremely important material to be used in combination with metallic nanolayers as a Surface-Enhanced Raman Scattering (SERS) substrate for biological and chemical analysis, demonstrating excellent biocompatibility and chemical inertness. These materials show their own Raman background signal lateral distribution, mostly from crystalline skeleton, which has to be considered. A nano-Raman setup using the optical fibre of a Scanning Near-Field Optical Microscope (SNOM), working in collection mode, is described and applied for mapping of such glass-ceramic. The collected Raman signal of Ti and P containing phase distribution in this near-field geometry reaches spatial resolution around 50 nm.