Nano-IR spectra of Au(111) sc /C9t in the spectral range considered here have four main regions with broad peaks. In the region from 1000 cm -1 to 1430 cm -1 , a broad absorption spans in the range between 1000 cm -1 to 1150 cm -1 , maximum absorbance around 1050 cm -1 (figure ). As represented in table 1, contribution to this band arises mainly from DNA backbone vibrations, i.e. the ν(C-O) of deoxyribose and the symmetric stretching of the phosphodiester, ν s (PO 2 -). A medium intense peak at 1205 cm -1 is assigned to asymmetric ν as (PO 2 ) -. It is noted that peak intensities are not comparable quantitatively over the full spectral range because the spectral range is covered using four different QCL stages which are tuned independently.