This article reports on a research project that obtained the normal Raman and surface‐enhanced Raman spectrum of three controlled substances: morphine, codeine, and hydrocodone.
The spectra were assigned with the aid of density functional theory. Because of intense fluorescence, normal Raman spectra suffered from poor signal‐to‐noise, even when differential subtraction techniques were used. On the other hand, surface enhancement by Ag nanoparticles both enhanced the Raman signal and suppressed the fluorescence, enabling more sensitive detection and identification. The article also presents a set of discriminant bands, useful for distinguishing the three compounds despite the similarities in their structures. (publisher abstract modified)