Sledovanie koncentrácie oxidu dusného v ovzduší metódou laditeľnej diódovej absorpčnej spektroskopie

Abstract

This diploma thesis deals with monitoring nitrous oxide concentration in air using tunable diode laser absorption spectroscopy (TDLAS). The theoretical part focuses on the importance of nitrous oxide in the atmosphere, its main natural and anthropogenic sources, and its role in the greenhouse effect and ozone layer depletion. Furthermore, the thesis describes the basic principles of absorption spectroscopy, the Beer-Lambert law, spectral properties of the N₂O molecule, and the possibilities of its detection using modern optical methods. The experimental part is devoted to the description of the measuring setup based on a quantum cascade laser, detector, and signal processing using the 2f-WMS method. The thesis also includes system calibration, estimation of measurement uncertainty, stability analysis using Allan deviation, and evaluation of the dependence of the measured signal on nitrous oxide concentration. The aim of the thesis was to verify the suitability of the TDLAS method for the detection of low concentrations of N₂O and to assess its applicability for laboratory and potentially also field measurements.