Infrared absorption, Raman, and SERS investigations in conjunction with theoretical simulations on a phenothiazine derivative

The vibrational characterization of the most stable conformer of 10-isopentyl-10H-phenothiazine-5,5-dioxide (10-1-10H-P-5, 5-D) was performed by means of infrared absorption, Raman and surface-enhanced Raman spectroscopy (SERS). Hartree-Fock and density functional theory calculations were carried out to find the optimised structures and the computed vibrational wave-numbers of the title compound. The comparison of SER spectra obtained only in activated silver colloid with the corresponding Raman spectrum reveals small shifts and changes in the relative intensities proving the partial chemisorption of the molecules on the silver surface. The electromagnetic mechanism represents the main mechanism of the overall SERS enhancement. The changes observed in the SER spectra at different pH values were explained by considering the reorientation of the adsorbed molecule with respect to the metal surface. (C) 2003 Elsevier B.V. All rights reserved.