Monitoring of Dye Adsorption Phenomena at a Silica Glass/Water Interface with Total Internal Reflection Coupled with a Thermal Lens Effect

摘要

Thermal lens speciroscopy was combined with total internal reflectance spectroscopy to develop a novel, highly sensitive analytical method that can detect non-fluorescent as well as fluorescent analytes at surfaces and interfaces. It was verified that when the total internal reflection method is coupled with thermal lens spectros-copy (HR-TIS), the thermal lens effect is induced by only the evanescent wave. The ability of depth profiling was shown. The detection limit of TIR-TLS was at an absor-bance of 3.0 x 10~ unit for Sudan II acetone solution, which is better than that of attenuated total reflection by a factor of hundreds. In addition, the adsorption of acridine orange on silanol groups on a glass surface could be monitored directly by TIR-TIS, and the adsorption isotherm agreed well with langmuir’s model. The depen-dence of surface density of anionic silanol groups on pH was determined by TIR-TLS measurements of aqueous acridine orange solutions buffered in the pH range be-tween 2.7 and 11.5.