Plasmonics for Enhanced Vibrational Signatures

Abstract

Vibrational signatures provide key information on the molecular composition of matter and on molecular structure and structural changes. Vibrational transitions in molecules can be probed optically by infrared absorption (IRA) and Raman scattering (RS). Exploiting local optical fields in the vicinity of plasmonic nanostructures has revolutionized optics and spectroscopy and opens up exciting new capabilities, particularly also for vibrational spectroscopy. The basic prerequisites for plasmon-supported spectroscopy are strongly enhanced and highly confined local optical fields in the wavelength range applied in the respective spectroscopic method. Here, we review plasmon supported linear and non-linear vibrational spectroscopies. Our discussion includes incoherent effects such as surface enhanced Raman scattering (SERS), surface enhanced pumped anti-Stokes Raman scattering (SEPARS), surface enhanced hyper Raman scattering (SEHRS), and surface enhanced infrared absorption (SEIRA), as well as coherent Raman techniques such as surface enhanced coherent anti-Stokes Raman scattering (SECARS) and surface enhanced stimulated Raman scattering (SESRS). Emphasis will be placed on materials and nanostructures that efficiently support various vibrational spectroscopic methods. Selected applications of surface enhanced vibrational spectroscopy for chemical probing and sensing will be discussed.