Effects of Temperature and Humidity on the Absorption Spectrum and Concentration of N2O Using an Open-Path Sensor System

Abstract

This paper examines the effects of temperature and humidity on the absorption spectrum and concentration of nitrous oxide ((Formula presented.)) using a compact, portable open optical-path gas detection sensor system. We obtained the absorption coefficient and widened the linear function of the (Formula presented.) absorption spectrum related to temperature by theoretical analysis and the high-resolution transmission molecular absorption database (HITRAN). Afterward, we conducted real-time monitoring of (Formula presented.) in both campus and laboratory environments using lasers for a duration of 32 h and 6 h, respectively, and the results were compared and analyzed with the theoretical derivation. The results show that the concentration of (Formula presented.) increased with increasing environmental temperature but decreased with increasing humidity. Furthermore, the variations in temperature and humidity significantly affected the peak values of the second-harmonic (2f) and first-harmonic (1f) signals. Finally, the temperature (Formula presented.) concentration and humidity (Formula presented.) curves were calibrated separately, and temperature changes were positively correlated with the (Formula presented.) concentration, while humidity changes were negatively correlated with the (Formula presented.) concentration. The experimental results indicate that the concentration of (Formula presented.) and its absorption spectra are influenced by humidity and temperature, which has a significant reference value in the absorption and measurement of (Formula presented.) in practical applications.