VISUALIZATION OF THE ANGULAR-DEPENDENCE OF THE REFLECTED-RADIATION PHASE UNDER CONDITIONS OF A SURFACE-PLASMON RESONANCE AND ITS SENSOR APPLICATIONS

Angular dependences of the reflected-radiation phase were made visible for the first time under conditions of a surface-plasmon resonance. T he dependences were visualised by fringes of an interference pattern i n a plane where one coordinate represented the phase and the other cor responded to the angle of incidence. These fringes had an inflection o r a kink in the form of a step near a resonance minimum of the reflect ed-radiation intensity. An inversion of such a step was detected in th e course of biological binding on the surface when passing through the optimal conditions for the resonance. This effect made it possible to detect, with a very high sensitivity, changes in the surface state or the presence of a (bio)chemical reagent in the ambient medium. Determ ination of the angular position of such a step ensured that the dynami c range was wide. The results obtained confirmed conclusively the auth ors' own model proposed earlier to account for the behaviour of the ph ase. The method suggested is promising for use in (bio)chemical sensor s and analysers.