Deep-UV-based differential optical absorption spectroscopy (DOAS) system for the monitoring of nitric oxide

Abstract

The development of an Ultra Violet (UV) Differential Optical Absorption Spectroscopy (DOAS) fibre-optic sensor for the monitoring of nitric oxide gases is described in this paper. Experimental results describing the operation of this sensor with cylinder gases are presented. These experimental results are compared with existing published spectroscopic absorption measurements. The sensor was developed to operate within an exhaust environment and demonstrate a low susceptibility to interferences from other gases present. A LabVIEW program was created to interrogate the highest absorbing wavelength for nitric oxide and calculate the concentrations present before outputting them to the user. The lower limit of detection for the sensor was found to be 5ppm with response times of 3.4 seconds.