Fig. 3. Detectability of biomolecular spectra, qualitative analysis.

Maximum intensity raw spectra obtained for biomolecules mixed with S-MRS and P-MRS exposed in the upper sample tray (S-MRS Top, red; P-MRS Top, light blue) and in the lower sample tray (S-MRS Bottom, dark red; P-MRS Bottom, dark blue). Spectra were acquired with a 532-nm excitation wavelength (DLR Berlin) and with a 514-nm excitation wavelength (OU Milton Keynes). β-Carotene, naringenin, cellulose, and chitin were detected only on a few spots and only in the samples for which a spectrum is shown. Pure S-MRS and P-MRS samples did not yield any biomolecule spectrum. The same scale is applied for the spectral intensity.