Tip-enhanced nano-Raman analytical imaging of locally induced strain distribution in carbon nanotubes

Abstract

Tip-enhanced Raman scattering microscopy is a powerful technique for analysing nanomaterials at high spatial resolution far beyond the diffraction limit of light. However, imaging of intrinsic properties of materials such as individual molecules or local structures has not yet been achieved even with a tip-enhanced Raman scattering microscope. Here we demonstrate colour-coded tip-enhanced Raman scattering imaging of strain distribution along the length of a carbon nanotube. The strain is induced by dragging the nanotube with an atomic force microscope tip. A silver-coated nanotip is employed to enhance and detect Raman scattering from specific locations of the nanotube directly under the tip apex, representing deformation of its molecular alignment because of the existence of local strain. Our technique remarkably provides an insight into localized variations of structural properties in nanomaterials, which could prove useful for a variety of applications of carbon nanotubes and other nanomaterials as functional devices and materials.

Mapping the electromagnetic field confinement in the gap of germanium nanoantennas with plasma wavelength of 4.5 micrometers

“…The electromagnetic field enhancement is crucial for nonlinear 4 and second-order phenomena as the Raman effect. 5 Subwavelength confinement is critical for near-field microscopy 6 and few-molecule spectroscopy. 7 Both features depend on the nanoantenna geometry and on the dielectric function of the metal used to make the antenna e m ðxÞ ¼ e 0 m ðxÞ þ ie 00 m ðxÞ, where x ¼ c=k is the electromagnetic frequency.…”

A 1.7 nm resolution chemical analysis of carbon nanotubes by tip-enhanced Raman imaging in the ambient

“…4g, for CNT-2, the peak frequency of o þ G is 1,593-1,595 cm À 1 before bundling but increases 3-4 cm À 1 higher in the bundled area. Local variations in o þ G frequency of CNT have been reported in AFM-TERS literatures as results of change in chirality 31 , local strain 32 , and most of time, unknown reasons. However, our high-resolution peak shift images clearly demonstrate the shift of electronic structure because of bundling since straight CNTs were chosen to exclude local strain effect 32 .…”

“…Local variations in o þ G frequency of CNT have been reported in AFM-TERS literatures as results of change in chirality 31 , local strain 32 , and most of time, unknown reasons. However, our high-resolution peak shift images clearly demonstrate the shift of electronic structure because of bundling since straight CNTs were chosen to exclude local strain effect 32 . In addition, the existence of defect seems to affect the G-band phonon since o þ G is particularly high (1,600-1,604 cm À 1 ) at the end of CNT-3.…”

Distinct Adsorbed States of DNA and RNA Bases Investigated by Flocculation-Assisted Surface Enhanced Raman Scattering

“…Furthermore, MNPs can be attached to the tip of cantilevers or sharpened optical fiber probes for near-field Raman spectroscopy. Such fabrication is expected to provide us with Raman images in single molecule sensitivity and a spatial resolution of a few nanometers [13,14].…”