| An interfacially sensitive fluorescence technique, which can provide information about the spatial and orientational distribution of fluorophore dipoles in a thin dielectric film, is evaluated in terms of its analytical capability. By using generated data with noise inserted, various data analysis techniques are compared for their potential to yield the density of fluorophores with respect to distance away from a dielectric interface, into a film (a fluorescence density profile). Analysis by techniques which prescribe a specific model, and then estimate parameters of that model (model-dependent techniques), are found to be most practical. Actual data curves are analyzed from thin films which are well defined in terms of relevant parameters (thickness, refractive index, fluorophore position and orientation). These films are constructed by using the method of Langmuir-Blodgett (L-B) deposition. The fluorescence technique is found to be capable of yielding at least two parameters of a model of a fluorescence density profile of films having a thickness of only one tenth of the wavelength of the fluorescence emission. The shape of data curves obtained for the TM polarization conforms to the fluorophore dipole orientation which is expected on the basis of other studies. A principle of reciprocity is found to be valid both theoretically and empirically. This principle is the theoretical basis for plans to render the fluorescence technique capable of gathering information under dynamic conditions. |
