Surface plasmon resonance transients at an electrochemical interface: time resolved measurements using a bicell photodiode

Thin film gold electrodes are frequently used for various sensor applications, and often it is necessary to know how the optical parameters of such an electrode depend on external electrochemical variables. In this work, we demonstrate a time resolved surface plasmon resonance (SPR) technique for studying the correlation between the optical and electrochemical parameters of a thin (similar to590 Angstrom) film gold electrode in a neutral aqueous electrolyte of 0.05 M NaNO3. The electrochemical double layer is charged by a potential step, generating a current transient. A bicell photodiode is used to record the resulting SPR transient, simultaneously with electrochemical measurement of the electrode current. A recently reported SPR detection technique is further extended for this purpose, and the working principle of this method is discussed in detail. The results show how voltage steps of different signs and magnitudes affect the optical properties of the Au surface. (C) 2002 Elsevier Science B.V. All rights reserved.