Dimethyl ether gas sensing using rotational absorption spectroscopy in the THz frequency region from 220 to 330 GHz

Abstract

Gas sensing for dimethyl ether (DME) using terahertz (THz) -wave absorption spectroscopy is demonstrated. Spectral absorption measurements for pure DME at room temperature and moderate pressures (1−8Torr, 1.33−10.67 mbar) are carried out in the frequency range of 220−330 GHz using a broadband microelectronics-based THz wave spectrometer. Measured transition frequencies and absorption strengths are in good agreement with literature and extend the prior work to conditions where considerable pressure broadening occurs, resulting in blended spectral features. Experimentally observed spectra are compared with simulated spectra, based on documented transition frequencies and absorption strengths. Collisional self-broadening half-widths for DME are derived by considering the pressure dependence of the linewidths of isolated transitions and were determined to be 0.41 ± 0.04 cm−1atm−1 (12.1 GHz bar−1). The results illustrate the potential for quantitative DME gas sensing in industrial and environmental applications using THz-wave spectroscopy.