Spectra of NH3, NH2D, and CO have been obtained interferometrically, using the large lamellar grating interferometer at The Johns Hopkins University. The CO spectrum is used to illustrate the technique, and to show that some information may be obtained directly from the interferograms, without recourse to a numerical Fourier transformation. The spectrum of NH3 shows pure rotation and inversion transitions in ν2 vibrational fundamental.
ERNEST V. LOEWENSTEIN, "Interferometric Spectra of Ammonia and Carbon Monoxide in the Far Infrared," J. Opt. Soc. Am. 50, 1163-1165 (1960)