CEAS

Incoherent BroadBand Cavity-Enhanced Absorption Spectroscopy (IBBCEAS)

Among the variety of different detection methods direct spectroscopic absorption techniques based on high finesse optical cavities appear to be very promising for highly sensitive in situ trace gas detection in real time with high spatial resolution. 

In recent years a powerful new approach, Incoherent BroadBand Cavity-Enhanced Absorption Spectroscopy (IBBCEAS), has been developed at University College Cork (UCC), Ireland. In IBBCEAS, the light from a bright incoherent source (e.g. a short-arc lamp, high power LED, etc.) is transmitted through an optically stable cavity and dispersed with a grating monochromator and detected by a charged coupled device (CCD) detector.

The measurement principle combines the simplicity and robustness of conventional optical absorption spectroscopy with the enhancement concepts developed in cavity ring-down spectroscopy. The broad simultaneous spectral coverage allows multiple species to be detected and interfering atmospheric constituents to be accounted for.

In 2007 an IBBCEAS instrument with an extraordinarily long resonator of 20m baselength was successfully intercompared with other spectroscopic methods using the SAPHIR simulation  chamber at Forschungszentrum Jülich (FZJ). The target species of this intercomparison campaign were the urban pollutant NO₂ and the night-time radical NO₃.

In close collaboration with UCC a new IBBCEAS instrument will be set up at the SAPHIR chamber in order to complete the suite of highly sensitive spectroscopic detection techniques for trace gases and free radicals.

Principle open-path IBBCEAS setup

Within the SAPHIR chamber the cavity length d will be 20 m.

Detection principle of IBBCEAS

Expected Accuracy