摘要
In 1974,Fleischmann et al.found an unexpectedly enhanced Raman signal on the surface of roughened silver electrode,and attributed the signal enhancement to an increased surface area[1].Three years later,Van Duyne et al.proved that the significantly strong Raman signals come from the surface enhanced efficiency,and discovered surface-enhanced Raman spectroscopy(SERS)[2].Subsequently,collective oscillations of the electrons on nanostructured metals under the optical excitation are clearly defined as the fundamental of SERS[3].After several decades of its first observation,SERS has enjoyed steady growth of interest in the research community,and it has become a commonly used and ultrasensitive sensing technique,in which the inelastic light scattering of molecules,as the unique molecular vibrational fingerprints,can be enhanced by one million times.And by placing the molecules within a nanogap between two plasmonic metal nanoparticles,the single molecule SERS can even be allowed,which benefits enormously from the enhancement of localized electromagnetic field[4,5].
