To overcome the limitation set by the ATR – IR method the same coated paper sample
was also measured in the IRRAS mode.The resulting s- and p- polarized spectra
are shown in figure 3. The left side in figure 3 shows the spectrum obtained with
s- polarized light and the right spectrum was measured with p- polarized light. One
immediately sees that in both cases all but two peaks point down in the spectrum.
Therefore, one can assume that the IRRAS method actually sees both coatings, as the
two peaks pointing up around 1500 cm-1 and around 860 cm-1 are most likely thin
film peaks. The peak around 860 cm-1 has a very unusual form for an IR peak. The
form of this peak would suggest that it might stem from a mechanical vibration.
This peak will be discussed later.