Intra cavity laser absorption spectroscopy (ICLAS) is proposed as a too for in-situ, real-time detection of atmospheric trace molecules (ppb) of medium-large size (benzene, toluene...).
ICLAS allows multiplexed broad-band detection of broad spectral feature with extremely high sensitivity.
Recent progress in solid-state lasers make it possible to build an improved and portable ICLAS spectrometer, possessing a resolution well suited to detection of the first overtone transitions of X-H vibrational modes (X = C, O. N...), in the wavelength range 1-2 micrometers.
In large molecules, the unresolved rotational structure produces an effective broadening which will be partially removed by cooling the sample in a molecular slit-jet. The vibrational structure thus revealed will be used as a molecular 'fingerprint' to allow discrimination of species coexisting in the sample.