DIRECTIONAL, ENHANCED FLUORESCENCE FROM MOLECULES NEAR A PERIODIC SURFACE

We extend the research of Holland and Hall on the use of waveguide mod es to enhance the fluorescent signal from a layer of molecules [Opt. L ett. 10, 414 (1985)] by incorporating a grating into the basic sample structure. Our measurements show that the combination of the direction ality imposed by the grating and the previously reported enhancement m echanism has the effect of increasing the intensity of the signal dete cted over a narrow angular range from a layer of fluorescing molecules by a factor of approximately 1000 over that from a reference sample. Simultaneously our method allows for both polarization and wavelength discrimination of the emitted radiation because of the characteristic nature of the incorporated grating.