SO2 Monitoring With Solid State-Based UV Spectroscopy Compact Apparatus

We propose a solid state-based spectroscopy compact apparatus for monitoring environmental SO2, particularly suitable, for example, for volcanic applications. A prototype system, with a 170-mm long optical path, was assembled and tested using a commercial LED operating at 285 nm and a large area silicon carbide. The laboratory tests were carried out using calibrated quartz cuvettes containing SO2 at fixed concentrations and standard SO2 gas with 20% of O-2 and complemented with N-2 dry gas to fill the optical system chamber. Optical signal attenuations in the chemically interactive chamber follow the Beer-Lambert-Bouguer law in all the performed tests and a 0.16 ppm/pA nominal chemical resolution and +/- 0.8 ppm concentration error were obtained from the experimental data for the current prototype.