Potential of thermo-optical methods for the study of molecular layers bonded to a flat glass surface

Abstract

Thermal-lens spectrometry and photothermal deflection spectroscopy (mirage-effect spectroscopy) are used to study active bright red 5SKh bonded to a glass surface. The theoretically calculated dependence of the thermal-lens signal on the absorbance of the surface-absorbing layers on a nonabsorbing substrate is used to evaluate the concentration of the reagent in the bonded layer. The concentration of the reagent varies in the range of (2–8) × 10−11 mol/cm2, depending on the method of surface modification. Using photothermal deflection spectroscopy, it is shown that the thickness of the layer on the glass surface does not exceed 700 nm. Data obtained by the thermo-optical methods are supplemented with the results of the analysis of the surface relief obtained using electron microscopy in the secondary electron emission mode, and the uniformity of the modification of the sample surface is characterized. Based on the obtained data, a comparative analysis is performed for the potential of the considered methods for the investigation of the molecular layers bonded to the flat glass surface.