Far-Field Spectroscopy and Surface-Enhanced Raman Spectroscopy (SERS)

The ability to provide the accurate molecular identity of analytes in aqueous and organic solutions, in the gas phase, and in solids makes Raman spectroscopy an extremely versatile technique in the field of applied physics, material science, chemistry, and biology. The advancement of the Raman spectroscopy, however, suffered from its inherently low signal strength, despite holding great promises. However, with the demonstration of many orders of magnitude enhancements in the Raman signal on or near the plasmonic surfaces, the discipline of surface-enhanced Raman spectroscopy (SERS) was born, which directly addressed this drawback of the Raman effect. Since its accidental discovery in the year 1974, there has been a lot of progress made in understanding the theory behind the SERS. Parallel advancements in the designing and production of well-defined SERS substrates and in the instrumentation have now made it possible to widely apply SERS in the field of analytical quantification, chemosensing, agricultural science, medical science, chemical warfare, environmental science, biological science, etc. In this chapter, we aim to provide the reader with a basic concept behind the surface enhancement effects, an account of some important types of SERS substrates, and various applications of SERS.