Terahertz-wave absorption gas sensing for dimethyl sulfoxide

Abstract

Rotational absorption spectroscopy for dimethyl sulfoxide (DMSO) is characterized in the 220-330 GHz frequency range using a robust electronic THz-wave spectrometer, for the development of THz gas sensing for this compound of commercial relevance. DMSO is a common solvent used in many food, pharmaceutical, and manufacturing applications, and can present danger to human health and the work environment; hence, remote gas sensors for DMSO environmental and process monitoring are desired. Absorption measurements were carried out for pure DMSO at 297 K and 0.4 Torr. DMSO was shown to have a unique rotational fingerprint with series of repeating absorption features. The frequencies of transitions observed in the present study are found to be in good agreement with prior experimental work and spectral simulations based on rotational parameters. The sensor developed here exhibits a detection limit of 1.3-2.6 x 1015 DMSO molecules/cm3 per meter of absorption pathlength, with the potential for greater sensitivity with signal-to-noise improvements. The study illustrates the potential of all electronic THz-wave systems for miniaturized remote gas sensors