Optical measurements of 14CO2 using cavity ring-down spectroscopy

Measurements of radiocarbon ($^{14}$C) provide a unique platform in order to determine the age of a material or alternatively for source attribution between biogenic and petrochemical sources. We describe a cavity ring-down spectrometer which uses an infrared quantum cascade laser to probe the fundamental of $^{14}$CO$_{2}$. This instrument offers one of the highest sensitivities which has been reported in the mid-infrared and has fully automated spectral scanning for continuous data acquisition. Despite the ultra-low abundance of $^{14}$CO$_{2}$ in the atmosphere (1.2 pmol/mol relative to $^{12}$CO$_{2}$) we have been able to rapidly record the $^{14}$CO$_{2}$ transition and determine the origin of carbon dioxide samples. Our experimental approach and future improvements to the instrument will be discussed as well as selected measurement targets