device used for the measurements of this work is a single sensor device, which
is based on the resonance of surface plasmons as detection principle. The setup,
which is shown in figure 11 and which was assembled by Dr.
Birgit Kieser , was initially suggested
by Kretschmann in 1968 :
angle, parallel-polarized white light is focused through a glass prism onto
a silver film on condition of total reflection. The surface plasmons are excited
at the back surface of the silver layer, which is evaporated onto the glass
prism. The reflected light is coupled into a multimode fiber and detected by
a diode array spectrometer. A sensitive polymer layer is coated onto the top
of the silver film. The resonance wavelength of the surface plasmons is influenced
mainly by the refractive index n
and partly by the thickness d
of the sensitive layer (for all sensitive layers used in this work practically
only changes of the refractive index n
play a role ).
Due to a high temperature dependency of the refractive index, the temperature
was kept constant by a thermo-regulator. More details of the setup can be found
in literature .
figure 11: Schematic of the RIfS
array setup. The yellow bubbles show the effects when analyte sorbs into the
polymer layer (magenta).