Submillimetre-Wave Spectroscopy as a Tool for Environmental Monitoring.
Jennifer van Wijngaarden, Shahram Shadfar, Yunjie Xu and Wolfgang Jäger
High resolution spectroscopy has been extended to the Terahertz region through the use of backward wave oscillators. This frequency region holds promise for monitoring emissions from industrial sources as many medium sized molecules exhibit strong rotational transitions in this range. We recently constructed a new submillimetre-wave absorption spectrometer which can be continuously tuned from 78.33 to 118.1 GHz. The absorption spectrum of CO, a criteria pollutant, was measured with a linewidth of 300 kHz. Further improvements are in progress which extend the operating range to 1030 GHz. The sensitivity will be improved through the incorporation of a phase locked loop, source modulation and a bolometer detector.