The tip-enhanced Raman spectroscopy (TERS) imaging technique is designed to provide correlated morphological and chemical information of molecules under fifty nanometers in size. To do this, a TERS system essentially brings together the benefits of scanning probe, microscopy, and spectroscopy technologies. Incident light is coupled to the plasmonic resonance of the excitation probe to generate Raman signals. However, the quality and resolution of current TERS images is limited due to how uncoupled light directly excites the background of the image and causes it to blur.
Profs. Ruoxue Yan, Ming Liu, and their colleagues from the University of California, Riverside have developed a remote-excitation TERS (RE-TERS) probe that prevents uncoupled light from compromising the quality of TERS images. The probe utilizes silver nanoparticles as nanoantennas to mediate the coupling of light to surface plasmon polaritons (SPPs) in a sharp-tip silver nanowire to excite Raman signals remotely. The probe is easy to produce and overcomes the greatest obstacle that stands between scientists and TERS images with high spatial resolution at the nanoscale.
Fig 1. RE-TERS mapping of a chemical vapor deposition-grown molybdenum disulfide (MoS2) monolayer flake. (a) atomic force microscopy image of the MoS2 flake on an ultrasmooth gold substrate with the line-scan shown in (b). The markers indicate the edge of the MoS2 flake (green) and two wrinkles (light blue and orange).
The probe may be used