Herein, for the first time, we report the single molecule surface enhanced resonance Raman scattering (SERRS) and surface enhanced Raman scattering (SERS) spectra with high signal to noise ratio (S/N) using plasmon-active substrates fabricated by sprouted potato shaped Au-Ag bimetallic nanoparticles, prepared using a new one-step synthesis method. This particular shape of the nanoparticles has been obtained by fixing the amount of Au and carefully adjusting the amount of Ag. These nanoparticles have been characterized using scanning electron microscopy, extinction spectroscopy, and glancing angle X-ray diffraction. The single molecule sensitivity of SERS substrates has been tested with two different molecular Raman probes. The origin of the electromagnetic enhancement of single molecule Raman scattering in the presence of sprouted shape nanoparticles has been explained using quasi-static theory as well as finite element method (FEM) simulations. Moreover, the role of (i) methods for binding Raman probe molecules to the substrate, (ii) concentration of molecules, and (iii) Au-Ag ratio on the spectra of molecules has been studied in detail.

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The metal oxide semiconductor gas sensor technology is robust and has quick response times. In this work, aluminium and tin codoped zinc oxide (ASZO) thin films were synthesized by a sol-gel dip-coating process as sensors for the greenhouse gas nitrogen dioxide (NO 2). The prepared ASZO thin films were characterized using such techniques as X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM) and photoluminescence (PL) emission studies in order to analyze the elemental confirmation, particle size, surface roughness and optical emission properties, respectively. The XRD data reveals the hexagonal structure of ASZO and that the preferential orientation is along 2θ = 36.19 •. SEM images of the ASZO thin film exhibit rod-like formations of ASZO on the substrate. The ASZO films show enhanced sensing behaviour, sensing NO 2 gas even at 2 ppm at an operating temperature of 170 • C. The response and recovery times were determined to be 30 and 20 s, respectively.

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