Far-infrared Fourier transform emission spectroscopy in the gas phase

We report in this Letter several techniques that we have developed for emission spectroscopy in the far-infrared spectral region (30–500 cm−1) using a high resolution interferometer. The thermal emission of gas phase polycyclic aromatic hydrocarbons has been recorded from a furnace while the spectra of lighter molecules and radicals, such as H2O, OH, NH3, NH2 and HCN, were obtained from a microwave or a radiofrequency discharge. This Letter presents the details of each experimental technique used in the laboratory, discussion of the experimental difficulties that were overcome with our methods, and samples of the resulting spectra we obtained. The analysis of these spectra will be published elsewhere.