Gas analysis software for selected techniques of laser absorption spectroscopy

Abstract

The article presents a software ‘SALAS’ (Spectral Analyzer for Laser Absorption Spectroscopy) dedicated to the analysis of gas absorption spectra. The analysis takes into consideration performances of two laser absorption spectroscopy techniques i.e. cavity enhanced absorption spectroscopy (CEAS) and wavelength modulation spectroscopy (WMS)[1]. It is based on data imported from the HITRAN database. The main task is to determine spectral range of operation providing effective results of these gas detection techniques. The SALAS is not only able to identify spectral lines for the defined gas but also to indicate so-called “fingerprint” line with the least impact of other gases (interferents). For this purpose, the software gives the possibility to import data of several gases and to define the detected gas. The implemented procedures indicate the influence of the interferents absorption spectra on the absorbance of the tested gas. This operation is particularly important for CEAS technique in which the main importance is to indicate characteristic absorption line. This provides high sensitivity and measurement selectivity. The developed software was tested for the identification of selected gases, called the disease biomarkers in the exhaled air. These tests were performed in the frame of the project ‘Sensormed’ taking into consideration the detection of nitrous oxide, methane and carbon monoxide[2,3]. Correct operation of the SALAS was also defined by comparing the results of the absorption lines analysis for other gases to the results found in the literature.