Application of thermal-lens spectroscopy coupled with incident-angle-dependent total-internal reflection to adsorption phenomenon of dyes on glass/solution interface

We developed a novel non-destructive depth profiling method involving incid ent-angle-dependent internal reflection spectroscopy coupled with thermal-l ens spectroscopy. It was confirmed that the thermal lens originated from dy es in the vicinity of the prism/solution interface, and that a depth-profil ing analysis of the interface is possible. The detection limit of the propo sed method with a 20 mW excitation laser corresponded to 1 x 10(-5) absorba nce unit, which is better than that of attenuated total-reflection methods. This method was applied to dye-adsorption phenomenon on a glass/solution i nterface. The result agreed well with that expected from the dissociation c onstants of both the silanol group and acridine orange.