A Laser Based Gas Sensor for Environmental Monitoring
Hans Osthoff and Wolfgang Jäger
A tuneable diode laser absorption spectrometer for open-path real-time monitoring of atmospheric trace gas pollutants is being developed. In the first place, a bench top version of the spectrometer was put constructed. This spectrometer employs an in-house designed low-pressure sample cell in a Herriott multipass configuration. The sample cell can be operated in either static or in pulsed jet expansion mode. The pulsed mode offers the advantage of cooling rotationally excited states, which leads to more heavily populated low-energy states and therefore superior absorption signals. Example spectra of carbon dioxide and hydrogen sulfide will be presented.