Spectral fluctuation in SERS spectra of benzodiazepin molecules: The case of oxazepam

The surface‐enhanced Raman spectroscopy (SERS) spectra of a benzodiazepine molecule, oxazepam, have been recorded using a nanoporous silica matrix containing gold nanoparticles as SERS substrate. In the measured spectra, we clearly observe spectral fluctuations, with slight shifts in wavenumber, appearance, and disappearance of peaks and variations in the shape of some peaks. By comparison with spectra simulated by density functional theory, we attribute those fluctuations to the experimental signature of various adsorption sites of the molecule on the gold surface. The effect of temperature and laser power was also studied, suggesting that changes in absorption sites can be optically activated. Such features could cause misinterpretation of SERS spectra and errors in the identification of drugs. We suggest that they should be systematically considered for the correct interpretation of SERS spectra of drug molecules.