Yifan Chen, Ruyue Cui, Jialiang Dai, Bing Luo, Haofeng Zhang, Wei Xiao, Yaoxin Wang, Wenjie Zhang, Weiguang Ma, Gang Zhao, Xukun Yin, Lei Dong, Hongpeng Wu
This work presents what we believe to be the first application of light-induced thermoelastic spectroscopy (LITES) to methane isotope detection, demonstrating the development of a compact, low-power system. By targeting the near-infrared absorption lines of the two isotopologues 13 CH 4 and 12 CH 4 and applying Kalman filtering, the system simultaneously measures their absolute concentrations and isotopic abundance ratio while achieving improved signal-to-noise performance. Experimental validation with chemically synthesized methane and biogas from a wastewater treatment plant demonstrates that the isotopic ratios obtained are in excellent agreement with high-precision mass spectrometry, allowing reliable discrimination of methane sources. This study establishes LITES as a promising approach for portable, low-power, and in situ isotope monitoring.