We propose a compact innovative spectroscopy system operating in the UV range. In the actual version, designed for gas, it exhibits: an aluminium tubular optical chamber (length can be adjusted; currently is 20 cm); a cheap commercial UV LED; a SiC visible blind UV detector designed and manufactured at the CNR-IMM facilities. The team developed also the electronic chain for wireless remote real time read out; while able to deal with pA current levels, it uses very cheap components and construction technology. The system could be used for liquid analysis by opportune chamber modification. It could fit in: water quality (monitoring dissolved elements and micro-organisms exploiting the UV absorption/fluorescence of DNA and proteins); concentration measurements of gases such as SO2, NOx, H2S and ozone. Whilst such analyses are performed with high accuracy in laboratories, it would be highly beneficial to have portable system for in-field real-time measurements. The first prototype was tested for concentration measurements of SO2, a gas of particular interest in volcanic monitoring, obtaining a resolution ≤ 2 ppm.
Innovative characteristics are: low cost; compactness (compared to lab. equipment) allowing in situ measurements; remote control and data acquisition. It is in fact a solid state apparatus with cheap commercial LED source and a large area, high sensitivity and low dark current UV visible blind SiC detector. All these features ensure: short optical path (≤ 20 cm in the case of SO2 detection) adjustable according to the application; low power consumption; very high detection ability. Adopting SiC visible blind detector, fakes due to photoemission in the visible of chemical interfering are excluded. Moreover, detector thermal stability reduces the number of free parameters during the measurements in particular in hostile environments. Competitive advantages of the portable spectrometer are its robustness and insensitivity to environmental temperature and humidity. In the specific case of SO2 detection for example, compared to electrochemical sensors commonly used for this application, it does not present chemical saturation problems, nor require periodic re-calibration and a long life is expected also in a hostile environment such as volcanic one.