A.A. Ruth
Physics Department and Environmental Research Institute, University College Cork, Cork, Ireland
Absorption spectroscopy is among the most flexible quantitative approaches to detect trace constituents in the atmosphere. The required sensitivity for monitoring purposes is generally achieved by maximizing the absorption path-length at the expense of spatial resolution, for example in long-path differential optical absorption spectroscopy (LP-DOAS). The use of optical cavities, however, provides an alternative mean to generate very long effective path-lengths for the ultra-sensitive detection of trace species with high spatial resolution (point measurement).
Among various experimental implementations of spectroscopic cavity technology, broadband methods employing incoherent light sources have been shown to possess a number of attractive features for in situ real time detection of trace gases, such as multiplexing features (several trace gas monitoring), high sensitivity, good selectivity and time response, experimental simplicity and robustness.
After a brief introduction concerning the principles of incoherent broadband cavity-enhanced absorption spectroscopy (IBB-CEAS) an overview of typical applications will be given; advantages and limitations of the method will be discussed. Specific ways of utilizing IBB-CEAS for the detection of NO3 and HONO will be presented.
