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[Display omitted] • Fabricating robust and reproducible SERS active Gold decorated MoS 2 substrate. • Efficacy in detecting molecules at ultralow concentrations of 4-Mpy. • Detection of thiram in aqueous solution and carrot peels at trace concentrations. • Cost effective SERS active scaffold with long shelf life yet easy to fabricate. This paper is focused on simple fabrication of robust and reproducible SERS active substrate through self-assembly of gold nanoparticles (AuNps) entrapped in the Langmuir Blodgett (LB) film of MoS 2 flakes. The as prepared Au-MoS 2 substrate can detect SERS signals of 4-Mercapto Pyridine (4-Mpy) molecules at trace concentrations down to 10-12 M. The substrate has been further employed in detecting thiram (TH) both in aqueous solution and in carrot peels (CPls). The limit of detection (LOD) of TH in aqueous medium and in CPls have been estimated to be ∼ 5.18 and 10.16 pM respectively. We believe that the applicability of this SERS active substrate may be extended in the trace detections of explosives, drugs and in diagnostic applications. [ABSTRACT FROM AUTHOR]

Raman spectroscopy is of significant importance in industrial gas analysis due to its unique capability of quantitative multigas measurement, especially diatomics (N2 and H2), with a single laser. This paper presents the development of a gas analyzer system based on high pressure Raman scattering in a multipass Raman cell and demonstrates its feasibility for real-time natural gas analysis. A 64-pass Raman cell operated at elevated pressure (5 bar) is used to create multiplicative enhancement (proportional to number of passes times pressure) of the natural gas Raman signal. A relatively low power 532-nm continuous wave laser beam (200 mW) is used as the source and the signals are measured through a cooled charge-coupled device grating spectrometer (30-s exposure). A hybrid algorithm based on background-correction and least-squares error minimization is used to estimate gas concentrations. Individual gas component concentration repeatability of the order of 0.1% is demonstrated. Further, the applicability of the technique for natural gas analysis is demonstrated through measurements on calibrated gas mixtures. Experimental details, analyzer characterization, and key measurements are presented to demonstrate the performance of the technique. [ABSTRACT FROM AUTHOR]