Quantum cascade laser-based tunable laser absorption spectroscopy for the detection of stable isotopes of CO2

We present a conceptual design and results on the determination of three stable carbon dioxide (CO2) isotopologues. The isotopic analyses have been performed using a quantum cascade laser (QCL)-based tunable laser absorption spectroscopy (TLAS) setup. A mid-infrared (MIR), tunable and narrow linewidth QCL is used as a light source to probe absorption lines at around 4.3 mm. Tuning the QCL in this selected region permits the simultaneous detection of three absorption lines of CO2 isotopologues including 16O12C16O, 16O13C16O and 16O12C18O. The result shows that the wavelength conversion method using the reference gas cell is well-suited for this technique.