Biophotonics: Near-field Raman Microscopy of Biological Membranes

University Of Rochester, Rochester NY

Investigators

Abstract

0086368 Novotny The objective of this project is to explore a new methodology to increase the spatial resolution of optical microscopy and spectroscopy. The instrument to be developed holds promise for gaining deeper insight into the functionality of nanometric structures embedded in complex environments such as single proteins in biological membranes. It is propose to develop a high resolution near-field optical microscope based on the effect of surface enhanced Raman scattering. In this technique, a sharp noble metal tip is held in close proximity over the sample surface. Properly polarized laser light illuminates the tip and induces a strong surface charge density at the tip. This leads to an enhancement of the exciting laser field. Rigorous calculations show that the intensity of the optical fields at the tip can be enhanced by 3 - 4 orders of magnitude over the intensity of the exciting laser light. The enhanced field at the tip enables a highly localized optical interaction with the sample surface thereby generating a Raman signal and thus a vibrational spectrum of the sample area right beneath the tip.