Absolute frequency metrology of the CHF3 8.6-μm ro-vibrational spectrum at 10−11 level

Abstract An optical-frequency-comb-referenced quantum cascade laser is used to perform wavelength-modulation Lamb-dip spectroscopy on a large number of ro-vibrational transitions falling in the CHF3 υ 5 fundamental band at 8.6 μm. The combined (statistical + systematic) fractional uncertainty in the absolute determination of the line-center frequencies ranges from 9 × 10 − 11 down to 2 × 10 − 11 . This represents an improvement by more than two orders of magnitude, as compared to a recent and extensive study performed with a high-resolution FTIR spectrometer [1]. Our investigation realizes a sharpened knowledge of the CHF3 spectrum over a wide interval, also managing to accurately determine the positions of very close, previously unresolved multiple ro-vibrational components.