FABRICATION AND CHARACTERIZATION OF URANIUM OXIDE DOPED SOL-GEL PLANAR WAVE-GUIDES FOR ATTENUATED TOTAL REFLECTANCE SPECTROMETRY

Planar integrated optical waveguides doped with fluorescent hexavalent UO22+ ions were fabricated by a sol-gel dip-coating process. Excitati on of a mode in these waveguides produced fluorescence emission that d ecayed in a highly uniform manner as a function of propagation distanc e. A comparison of methods for determining waveguide attenuation coeff icients by digital photography of the mode demonstrated that imaging t he UO22+ fluorescence emission is significantly more precise than imag ing the Rayleigh and Mie scattered light. The utility of these wavegui des for performing attenuated total reflectance measurements on substr ate-supported molecular films was also assessed. Both the fluorescence and scattering methods were used to determine the attenuation coeffic ient of an adsorbed heme protein monolayer. The fluorescence imaging m ethod was clearly superior; its use enables attenuation measurements o f very weakly absorbing, waveguide-supported films to be performed wit h significantly improved precision.