Seminars Archive

Applications of near field Raman spectroscopy

Abstract
Imaging with resolution below the classic diffraction limit of light (~lambda/2) is nowadays easily performed with non-optical microscopes, also called scanning probe microscopes (STM, AFM). More recently it has become possible to overcome the diffraction limit while still probing with photons in the visible range. The new domain of optics, referred to as near-field optics or nano-optics, has attracted an increasing interest in the last 15 years, due to the considerably reduced sample volume that is optically investigated by employing a near-field source (Scanning Near-field Optical Microscope, SNOM). The resolution is related to the size of the probe apex, reaching even below 50 nm. In near-field Raman (also called Tip enhanced Raman spectroscopy, TERS) optical interaction between the near-field and the sample is in terms of Raman scattering enhanced via plasmonic excitations at the probe tip. TERS combines near-field resolution with the richness in chemical information typical of Raman spectroscopy. Examples are given in the domain of single molecule detection and carbon nanotube characterization. Plasmons assisted luminescence excited by tunneling electrons will also be addressed.