Measurement of temperature-dependent line parameters of ammonia transitions near 1103 cm−1

Abstract

Accurate knowledge of the line parameters of ammonia (NH3) transitions is important for developing precise laser-based NH3 sensors. We report the measurement of line-strengths and temperature-dependent broadening coefficients of NH3 with N2, air, Ar, and CO2 for six transitions in the ν2 fundamental band near 1103 cm−1. The absorption feature contributed by the target transitions is of particular interest for combustion emission applications due to its strong absorbance and the minimal spectral interference from other species such as H2O, CO2, and NOX. In this work, we measured NH3 absorption spectra with different collisional partners at the temperature range of 296–573 K using a quantum cascade laser. Spectroscopic parameters were determined by conducting multi-line fitting of the measured spectra using the Galatry lineshape function due to the evident line narrowing effect. Our study will aid the development of mid-infrared NH3 sensors particularly for high-temperature applications.