Using sub-microliter cylindrical sample cells for photothermal lens spectrometry of stable and photo-labile species

A photothermal lens apparatus is described which uses a low-volume cylindrical sample cell, a chopped excitation laser, and a continuous probe laser. The lens element is formed by thermal diffusion from the irradiated sample volume, through the sample cell walls, Experiments to verify the apparatus are performed with dicyclopentadienyl iron in ethanol, The resulting signals are found to be relatively linear and reproducible Results obtained for ruthenium tris-bipyridyl chloride and perchlorate salts are not stable with respect to irradiation time. The later suggests ruthenium tris-bipyridyl photolysis with mild irradiation.