Tip enhanced Raman scattering: plasmonic enhancements for nanoscale chemical analysis

Abstract

Tip enhanced Raman scattering (TERS) is an emerging technique that uses a metalized scanning probe microscope tip to spatially localize electric fields that enhances Raman scattering enabling chemical imaging on nanometer dimensions. Arising from the same principles as surface enhanced Raman scattering (SERS), TERS offers unique advantages associated with controling the size, shape, and location of the enhancing nanostructure. In this article we discuss the correlations between current understanding of SERS and how this relates to TERS, as well as how TERS provides new understanding and insights. The relationship between plasmon resonances and Raman enhancements is emphasized as the key to obtaining optimal TERS results. Applications of TERS, including chemical analysis of carbon nanotubes, organic molecules, inorganic crystals, nucleic acids, proteins, cells and organisms, are used to illustrate the information that can be gained. Under ideal conditions TERS is capable of single molecule sensitivity and sub-nanometer spatial resolution. The ability to control plasmonic enhancements for chemical analysis suggests new experiments and opportunities to understand molecular composition and interactions on the nanoscale.

Influence of the Substrate to the LSP Coupling Wavelength and Strength

“…The LSP resonance wavelength depends on the size, shape, and material of NPs as well as the surrounding dielectric environment [ 1 – 4 ]. Because of its many attractive features, including exponentially enhanced electric fields near the interface between metal and dielectric medium and enhanced absorption at the plasmon resonant wavelength [ 5 , 6 ], LSPs have been integrated into many optoelectronic devices, including light-emitting diodes (LEDs) [ 7 – 9 ], photodetectors [ 10 , 11 ], solar cells [ 12 , 13 ], and other emerging technologies such as surface-enhanced Raman scattering (SERS) [ 14 – 17 ], tip-enhanced Raman scattering (TERS) [ 18 , 19 ], and chemical sensors [ 20 , 21 ].…”

Cell Imaging by Spontaneous and Amplified Raman Spectroscopies

“…In such a way, TERS analysis provides, simultaneously, the topographical (based on scanning microscopy data) and chemical (based on SERS effect at the tip apex) information of the investigated surface [30,31]. TERS technique has, in very recent years, allowed a deeper insight into the surface properties of many systems at the nanoscale, including biosystems [32][33][34][35][36].…”

Directionally enhanced probe for side-illumination Tip enhanced spectroscopy

“…[5][6][7] Specifically, since the experimental realization of tip enhanced Raman scattering (TERS), TERS imaging experiments have become possible in recent years on single molecules, graphene, carbon nanotubes, and biological samples. [8][9][10][11][12] With TERS gaining increasing importance as a chemical analysis technique and being commercialized by an incremental number of manufacturers, questions about the rapid analysis of TERS imaging measurements arise. For instance, to obtain an image of 256×256 pixels with acquisition time at 0.5 s/pixel for weak Raman scatterers, it will take ~9 hours.…”