表面等离子共振仪(SPR)（Surface Plasmon Resonance）

The SPR flow cell is custom made for the Multiskop and optimized for the adsorption measurements. The cell utilizes the Kretschman configuration (excitation of surface plasmona via a prism). The design of prism clamp maximizes the accessible angle range of the reflection scans and ensures that the beam is not chopped off.

Surface plasmon resonance (SPR) spectroscopy is a widely used optical reflection technique for the characterization of thin films. The central quantity of SPR spectroscopy is the surface plasmon coupling angle as a characteristic signature of the prevailing interfacial architecture. Adsorption processes lead to a shift of the surface plasmon resonance which is in the thin film limit directly proportional to the corresponding mass coverage. The aim of any SPR instrument is a precise measurement of the coupling angle with a sufficient high time resolution that fast kinetic processes can be monitored. In this paper, we compare two promising methods, an established one,the reflectivity tracking and a fairly new one, the mismatch tracking. Reflectivity tracking simply records the intensity of the light in the vicinity of the coupling angle. The shift of the plasmon modifies the intensity at the detector which can subsequently be used for data analysis. Mismatch tracking is more complex. Light is focused with a lens onto the prism base and the reflected light is detected via a bicell detector. The upper and lower cell integrate over a well-defined angular range of the fan of rays produced within the focus. The mismatch in the intensity between the upper and lower segments is evaluated and used to retrieve the unknown film parameter. In this contribution we suggest some decisive variations of the originally proposed scheme and demonstrate that the modified mismatch scheme yields a significantly higher sensitivity than the original one. Furthermore, it is demonstrated that this scheme is a superior alternative to reflectivity tracking.