Single-Walled Carbon Nanotubes as One-Dimensional Scattering Surfaces for Measuring Point Spread Functions and Performance of Tip-Enhanced Raman Spectroscopy Probes

This Article describes a method for the characterization of the imaging performance of tip-enhanced Raman spectroscopy probes. The proposed method identifies single-walled carbon nanotubes that are suitable as one-dimensional Raman scattering objects by using atomic force microscope maps and exciting the radial breathing mode using 785 nm illumination. High-resolution cross sections of the nanotubes are collected, and the point spread functions are calculated along with the optical contrast and spot diameter. The method is used to characterize several probes, which results in a set of imaging recommendations and a summary of limitations for each probe. Elemental analysis and boundary element simulations are used to explain the formation of multiple peaks in the point spread functions as a consequence of random grain formation on the probe surface.