A high-resolution, wavelength-scanning, fast-data-acquisition THz-wave spectrometer for trace gases

A compact, tabletop, high-resolution THz-wave spectrometer for trace gases was developed based on an injection-seeded THz-wave parametric generator. The chambers were purged with pure nitrogen gas to avoid strong absorption of THz-wave by water vapor. THz-wave spectra were measured over the wide frequency range of 0.8 to 2.4 THz with a resolution better than 100 MHz. Monitoring of sub-ppm H
₂
O concentrations in real time was demonstrated.