Interpreting MP-SPR and ellipsometry results

Ellipsometry and Multi-Parametric Surface Plasmon Resonance (MP-SPR) can both determine thickness OR refractive index.

Spectroscopic ellipsometry (SE) and MP-SPR can both determine thickness AND refractive index.

The main difference comes from the samples that the techniques can work with, which is given by the optical set-up of the two.

MP-SPR

MP-SPR measures from the back of the sample (the collected light does not travel through the sample or the air/liquid environment)
MP-SPR uses simple substrates with at least one plasmonic layer
MP-SPR utilizes the plasmon, which enhances sensitivity of the method especially for metals
MP-SPR can determine both d and n
MP-SPR is suited for measurements in gas or liquids
2 channels enable easy referencing (channel volume is 1 µL)

In ellipsometry, the collected light travels through the sample and its air/liquid environment
Ellipsometry works the best with very flat and very well reflecting substrates
In traditional ellipsometry, the optical parameters d or n need to be known
Ellipsometry is well suited for measurements in air
There is only 1 channel (channel volume is 1 mL, which makes biological experiments too expensive and without a reference channel difficult to validate)

The difference in optical set-up of Multi-Parametric Surface Plasmon Resonance and Ellipsometry.