Raman, IR, and surface-enhanced Raman spectroscopy of papaverineAn automated setup for in situ synthesis of the silver substrate and recording of the SER spectra

Abstract

Raman, IR, and surface-enhanced Raman scattering (SERS) were employed for the vibrational characterization of papaverine in the free and adsorbed state. The vibrational assignments were performed by means of density functional theory (DFT) calculations. The adsorption of the molecule was concluded with the isoquinoline and the benzene ring close to the silver surface in tilted orientations. Employing a sequential injection system, an automatized setup was developed for reliable, accurate and rapid recording of FT-SER spectra. The colloidal silver substrate was synthesized in situ in a 2 ml quartz cuvette by reducing silver nitrate with hydroxylamine. The FT-SER spectrum of papaverine obtained with the developed experimental setup exhibits the same characteristics as the SER spectrum obtained with a citrate reduced silver colloid.