Attenuated total internal reflection spectroscopy with an intracavity laser absorption spectrometer

A new type of intracavity laser absorption spectrometer (ICLAS) which emplo ys an intracavity prism in total internal reflection (TIR) configuration is presented. We report a theoretical background and a full characterisation of the spectrometer by measuring absorption spectra of NO2 and I-2 vapour a t room temperature in the 0.6 mu m spectral region. The ICLAS spectra measu red in the attenuated TIR configuration correspond to bulk absorption with an equivalent number of reflections of 2 x 10(4). They are identical to the conventional gas phase absorption spectra with no appreciable contribution s from (surface) adsorbed molecules. (C) 1999 Elsevier Science B.V. All rig hts reserved.