Contributions of Short-Range and Classical Electromagnetic Mechanisms to Surface-Enhanced Raman Scattering from Several Types of Biomolecules Adsorbed on Cold-Deposited Island Films

Abstract

Surface-enhanced Raman scattering (SERS) spectra of three different classes of adsorbates have been analyzed: (1) native and denatured calf thymus DNA and adenine, as examples of molecules with electronic transitions in the UV region only; (2) flavine adenine dinucleotide (FAD) and doxorubicin (DOX), as examples of chromophores with low extinction transitions in the visible region; and (3) β-carotene, as an example of a chromophore with a very high extinction coefficient for an electronic transition in the visible region. These molecules were adsorbed on silver island films that had an extinction maximum in the 450–660 nm region of the electromagnetic spectrum. The short-range mechanism of Raman enhancement has been demonstrated to contribute primarily to enhanced Raman scattering from molecules in groups 1 and 2, whereas the pure (classical) electromagnetic mechanism dominates the enhancement of β-carotene resonance Raman scattering.