SERS effect theoretical models

Results will be split into various sections the first of which will be fundamentals of hot spots. This will include a summary of the most important developments in the theory of SERS hot spots for both the EM and CT enhancement mechanisms. The second section will cover developments in tip-enhanced Raman spectroscopy (TERS) which represents the idealized hot spot. Then some issues regarding hot spots and the single molecule will be tackled such as the magnitude of enhancement required for single-molecule detection, the effects of molecular orientation with respect to the hot spot as well as the possible influence of optical forces. Sections 4.4 and 4.5 will cover developments in the imaging and fabrication of SERS hot spots, respectively, which have important implications for theoretical modeling as well control of SERS hot spots. The chapter will conclude by summarizing some of the applications of SERS hot spots that have been recently reported. 

The second main group of theoretical models associates the SERS effect with a large intrinsic polarizability through a resonance mechanism (RE). The resonating species depend on the specific model and can be the molecule modified by the presence of the metal, the metal itself affected by the molecular vibrations, or some mixed molecule-metal states. 

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