The spectra of four substances with both similar and different absorption spectra in the region of 3-4 m were recorded. The proof is resulted that close IR region (3-4 mm) become informative at processing of spectra by the least - square method. The measurements were made on a spectrometer SA - 2 and IRS - 31.
N. M. Ustuzhanin,
"Absorption spectra of medicines", Proc. SPIE 5311, 14th Symposium on High-Resolution Molecular Spectroscopy, (12 January 2004); doi: 10.1117/12.545743; https://doi.org/10.1117/12.545743