• Depero, Laura Eleonora
• Alessandri, Ivano

Abstract

1 ] Vibrational spectroscopy (infrared and Raman) can provide insightful information about intra- and interatomic bonds and physico-chemical processes dynamics (redox and acid-base reactions, conformational changes, etc.). This capa-bility offers several advantages over other ultra-sensitive techniques like fl uorescent tags or mass–based sensors, for example in terms of chemical specifi city and low invasiveness. However, in the case of reactions taking place in aqueous environment, like biological or biomimetic processes, the usefulness of infrared spectroscopy is severely limited by the strong contribution of water vibrational modes, that can over-whelm the analyte signals. In particular, the –OH stretching and bending modes can mask most of the spectral informa-tion about proteins or small biomolecules. Due to its rela-tive insensitivity to water, Raman can be a valid alternative to IR, yet the very low Raman cross-sections of many ana-lytes restrict the range of application of this technique to few cases involving resonant chromophores or labelling Raman reporters. Surface enhanced Raman scattering (SERS) takes advantage of surface plasmon-polaritons to increase the Raman cross-section of analytes that are either physisorbed or covalently linked to metal nanoparticles.

Topics

• nanoparticle
• impedance spectroscopy
• surface
• infrared spectroscopy