Laser spectroscopic monitoring of gas emission and measurements of the 13C/12C isotope ratio in CO2 from a wood-based combustion

We report on the application of a compact and field-deployable instrument, based on a continuous-wave fiber-coupled Telecom external cavity diode laser, to measure the 13C/12C isotope ratio in CO2 from a wood-based combustion. Carbon dioxide, the most important greenhouse gas, is a major product of combustion. The measurements of the 13C/12C isotopic ratio in CO2 from combustion emission permit one to identify the CO2 source and to study the temporal and spatial variations of pollution in the atmosphere. The average value of the 13CO2/12CO2 ratio is found to be (1.1011±0.0024)%. The corresponding δ-value relative to PDB standard is (−20.17±2.14)‰, which is in good agreement with the typical value of (−25±2)‰ for wood. Simultaneous monitoring of multiple species from gas emission has been performed using direct-absorption spectroscopy. The concentrations of C2H2, CO, CO2 and H2O were determined on the basis of integrated absorbance measured by least-squares fitting a Voigt lineshape to experimental absorption spectra.