Typical isotopologue-specific spectral scan in the 2310 cm^-1 region, taken from the TDLWintel data acquisition screen, using the dual-cell QCL spectrometer. Data are plotted in green and the real time fit to the data is in blue. 

 The left peak is ¹²CO2 and the right peak is due to ¹³CO₂.  The central peak arises from ¹²C¹⁶O¹⁸O, illustrating the simultaneous measurement of ¹³C/¹²C and ¹⁸O/¹⁶O in CO₂.  The peak absorbance for each line is approximately 10%.

 Pathlength = 7m, detectors:  LN2-cooled HgCdTe photodiodes.