Cavity Ring-Down Spectroscopy of Trace Components in Gas Mixtures for Breath Analysis and Environmental Applications
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Cavity ring-down spectroscopy (CRDS) is a direct absorption technique, which provides high detection sensitivity of gas, liquid or solid phases. By using high reflectivity mirrors, the effective absorption path length can be increased up to the hundred-kilometer range. In this work, a single mode tunable CW laser source was used to achieve high sensitivity detection with a narrow line width. The light source is a distributed feedback (DFB) diode laser. By changing the temperature and the current of the diode laser, the output wavelength was tuned across the absorption line peaks of carbon dioxide, methane (COv2, CHv4) and acetone (CHv3COCHv3). In particular, the main goals of this study are the optimization of the detection sensitivity of the isotope ratio (^13C/^12C) of indoor COv2 and CHv4, exhaled acetone analysis for diagnosing diabetes and studying of the gas content of natural water. In this study, first, the ^13C/^12C ratio of COv2 and CHv4 for room air will be discussed. Second, the results on acetone absorption spectrum for diabetic and non-diabetic people will be presented. Third, a membrane gas separation system and spectroscopic analysis of gas content will be described.
Bicer, Aysenur (2018). Cavity Ring-Down Spectroscopy of Trace Components in Gas Mixtures for Breath Analysis and Environmental Applications. Doctoral dissertation, Texas A & M University. Available electronically from