SERS Surface Enhanced Raman Spectroscopy Michigan State 表面增强拉曼散射的表面增强拉曼光谱 密歇根州.pdfVIP

SERS Surface Enhanced Raman Spectroscopy Christine J Hicks Spring 2001 MSU CEM 924 1 Introduction to SERS Surface Enhanced Raman Spectroscopy (SERS) is a Raman Spectroscopic (RS) technique that provides greatly enhanced Raman signal from Raman-active analyte molecules that have been adsorbed onto certain specially- prepared metal surfaces. Increases in the intensity of Raman signal have been regularly observed on the order of 4 6 8 14 8,10 10 -10 , and can be as high as 10 and 10 for some systems. The importance of SERS is that it is both surface selective and highly sensitive where as RS is neither. RS is ineffective for surface studies because the photons of the incident laser light simply propagate through the bulk and the signal from the bulk overwhelms any Raman signal from the analytes at the surface. SERS selectivity of surface signal results from the presence of surface enhancement (SE) mechanisms only at the surface. Thus, the surface signal overwhelms the bulk signal, making bulk subtraction unnecessary. There are two primary mechanisms of enhancement described in the literature: an electromagnetic and a chemical enhancement. The electromagnetic effect is dominant, the chemical effect contributing enhancement only on the order of an order or two of magnitude.7 The electromagnetic enhancement (EME) is dependent on the presence of the metal surface’s roughness features, while the chemical enhancement (CE