IMPROVEMENT OF SERS SIGNAL MEASURED BY PORTABLE RAMAN INSTRUMENT USING RANDOM SAMPLING TECHNIQUE

In recent years, portable Raman spectrometers and commercialized surface-enhanced Raman scattering (SERS) substrates have become increasingly popular. They have turned out to be great tools for both substance detection, identification, and on-site analysis. SERS is one of the methods of resolving the bottleneck issue of Raman spectroscopy due to its inherent low signal level of the inelastic scattering of photons on molecules. The localized electromagnetic field at the hot spots on the SERS substrates helps to boost up the Raman signal many orders of magnitude. However, there is difficulty in the collecting Raman spectra using SERS substrates caused by the distribution of the hot spots and/or investigated molecules at their proximity and photodegradation processes. This work addresses the technique to collect proper Raman spectra using SERS substrates and portable Raman spectrometers. We propose a random sampling technique that gives representative and high-quality spectra with high intensity and good resolution. This technique was tested on a home-built portable Raman spectrometer and SERS substrates based on metal film over nano-spheres (MFON) structure. The experimental results showed that the peaks of the Raman spectrum collected using random sampling technique are significantly narrower than those of spectra measured by conventional method, and can prevent samples and SERS substrates from photo-induced degradation. Potentially, this method can promote quantitative SERS and chemical trace analysis using portable Raman spectrometers. © 2022, Publishing House of Natural Science and Technology, VAST. All rights reserved.