{"doi":"10.1364/ao.405556","title":"Real-time isotopic methane detection using mid-infrared spectroscopy","abstract":"A real-time, nondestructive mid-infrared (mid-IR) platform was proposed for isotopic methane detection. The measurement system consisted of a tunable mid-IR laser, a miniaturized gas chamber, and a mid-IR signal receiver. The isotope ratio of the 12 C H 4 / 13 C H 4 was identified by measuring the mid-IR spectrum at λ = 3 . 2 − 3 . 5 µ m . In-situ 12 C H 4 / 13 C H 4 monitoring was then achieved by tracing the characteristic mid-IR absorption peaks assigned to the 12 C H 4 at λ = 3.328 µ m and 13 C H 4