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Surface Plasmon Resonance Spectroscop

construction by Dr. J. Nagel, IPF

Method: Surface Plasmon Resonance Spectroscopy (SPR); in-situ measurement of adsorption process and layer thickness

 

The Surface Plasmon Resonance Spectroscopy provides for very fast and uncomplicated quantitative determination of layer thickness.

Surface plasmon resonance data for the layers were obtained by means of the equipment consisting of a He-Ne-laser with λ=632.8 nm (Uniphase, USA), a semi-cylinder made of SF10 glass, a liquid flow cell with the volume of 2.5ml, and a E10V large area silicon photodiode detector with an integral preamplifier (Linos GmbH, Germany).

The laser emitted polarized light (polarization ratio 500 : 1) with power of 3mW onto a semi-cylinder whose plane face was coupled via an index matching fluid to the substrate examined (SF10 glass slide covered by the gold layer and then by the polyelectrolyte layers). The liquid flow cell was attached to the other side of the substrate and sealed with a rubber O-ring. The light was reflected onto the gold layer to excite surface plasmons. The intensity of the reflected light was measured by the photodiode. Both the semi-cylinder and the detector were mounted in an inhouse θ/2θ ; goniometer in such a way that the laser beam was incident on the detector at any angle of incidence. The goniometer and the photodiode were interfaced (Motion-Master 3000, Newport Corp., USA) to a personal computer.

An in-house 32-bit software package was used for goniometer control, data acquisition, curve modeling, and curve fitting. For scans over a certain range of incidence angles, a step width of 0.1◦ was used. The curves obtained were fitted according to Fresnel equations for a four-layer model (glass/metal/dielectric/ surrounding medium).

SPR measuring cell
SPR angle in dependence on time from two double layer polycation (PMBQ)/polyanion (PSS). The very fast adsorption kinetic is detected by the jump up of the SPR angle.
SPR curves of a monolayer PMBQ in dependence on ionic strength

Publication

  • Schwarz, S.; Nagel, J.; Janke, A.; Jaeger, W.; Bratskaya, S.:
    Adsorption of Polyelectrolytes with hydrophobic Parts more
    Progress in Colloid and Polymer Science 132 (2006) 102-109

  • Schwarz, S.; Nagel, J.; Jaeger, W.:
    Comparison of Polyelectrolyte Multilayers Built Up with Polydiallyldimethylammonium Chloride and Poly (ethyleneimine) from Salt-Free Solutions by in-situ Surface Plasmon Resonance Measurements more
    Macromolecular Symposia 211 (2004) 201-216
 
Surface Plasmon Resonance Spectroscop
Surface Plasmon Resonance Spectroscop

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Polyelectrolytes and Dispersions

Equipment

Layer thickness (SPR)

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