Precision spectroscopy of NH3 at 9.1 um by a comb-referenced quantum cascade laser

Absorption spectroscopy of NH3 at 9.1 ?m is demonstrated with a quantum-cascadelaser absolutely referenced to a Tm-fiber frequency-comb. Highly-accurate spectroscopic parameters are retrieved by a multiple-line fitting approach applied to the spectral manifold. © 2010 Optical Society of America.