High-precision CO2 isotopologue spectrometer with a difference-frequency-generation laser source.

A precision laser spectrometer for the detection of CO(2) isotopes is reported. The spectrometer measures the fundamental absorption signatures of (13)C and (12)C isotopes in CO(2) at 4.32 microm using a tunable mid-IR laser source based on difference-frequency generation. The spectrometer attains a precision of up to 0.02 per thousand for 150 s of averaging. An overall accuracy of 0.05 per thousand was obtained when sampling various calibrated reference gases.