The refractive index of ultrathin film of polymers is very high > 2.
No. Try XRR if films are thicker than 5 nm and have any signs of crystallinity.
XRR will give you the electronic density and the thickness, even if amorphous. From the electronic density, if you know the composition, you can calculate de density. Ellipsometry provides the refractive index as a function of wavelength, more difficult to correlate with the density.
Yes it is possible to measure/calculate averaged thickness of the layer and the density, some information in attached publication:
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I agree with all of you. But if there is not big difference on the critical angle (which used for density calculation) between the polymer and the substrate, it will be difficult to determine the density of the polymer. So it is difficult to determine the density exactly (it is depended on the polymer and the substrate). On the other hand, for the ellipsometry, many ultrathin polymers on Si substrate have very high refractive index (unreliable), especially if the thickness less than 10 nm. The refractive index at 630 nm is ranged from 2 to 2.5 (very big). The density calculated using the very high value of index is so high (Unreliable).
It is possible. Please go through this publication for further details. http://pubs.acs.org/doi/abs/10.1021/la501639z.
http://pubs.acs.org/doi/abs/10.1021/la501639z
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