Surface-enhanced Raman scattering (SERS) system for continuous measurements of chemicals in sea-water

A laboratory-based system for measurement of chemicals in sea-water with so l-gel-derived surface-enhanced Raman scattering (SERS) substrates is presen ted, The motivation behind this work was the development of a marinized pro totype sensor. A long-term spectral stability of better than 1 cm(-1) over a period of several months was observed, Photodegradation of the SERS layer was avoided by the choice of optical components and layout, Dielectric edg e filters and holographic notch filters were compared. Coated fibres were t ested and results are discussed in terms of fibre choice, reduction of back ground signal, sensitivity and time response. Continuous analysis was perfo rmed with two how-through cells, the first a modification to a standard gla ss cuvette and the second an improved in-house-constructed aluminium cell, SERS investigations on samples whose turbidity ranged from 0 to 400 NTU wer e performed with both cells, These tests show the suitability of the develo ped system for continuous monitoring of real samples and possible applicati on in on-line process control. Copyright (C) 2000 John Wiley & Sons, Ltd.