Next, nano-IR spectra with a different laser covering the higher wavenumber range from 2700 cm -1 to 3800 cm -1 were recorded on Au(111) sc /PEG-C9t incubated with S protein (figure ). Broad and strong bands were observed in the range from 2800 cm -1 to 3000 cm -1 for all spectra (table ). The peaks in this region can be assigned to asymmetric and symmetric C-H stretching vibrations of aliphatic methylene and methyl groups as they exist in all components in deoxyribose of DNA, in PEG, and protein side chains. Notably, the spectra for the PEG-rich phase feature a broad peak with a maximum at approx. 2860 cm -1 with a high-frequency shoulder at approx. 2930 cm -1 . Such a ν(CH) spectrum is typical for liquid PEG and hence clearly shows that PEG chains are amorphous, in line with the results of the layer thickness determination.