<title>Monitoring the surface adsorption of cyanine dyes via evanescent wave-excited fluorescence</title>

Abstract

By confining light from a diode laser within a solid planar waveguide in contact with a liquid sample, an electromagnetic field is produced which extends into the solution for a distance of several hundred nanometers. This `evanescent wave' has all the properties (e.g. power, wavelength, etc.) of light propagating freely through the solution, and as such can excite fluorescence if suitable fluorophores are present. The evanescent wave technique has the advantage of being confined to the very small volume found within 100 - 200 nm of the waveguide surface, so that molecules in the bulk solution, away from the waveguide, do not experience the evanescent wave field. Evanescent wave excited fluorescence is therefore a spatially-specific probe of surface phenomena at the liquid-solid interface.