Tip-Enhanced Raman Nanospectroscopy of Smooth Spherical Gold Nanoparticles
Ashish Bhattarai, Zhihua Cheng, Alan G. Joly, Irina Novikova, James E. Evans, Zachary D. Schultz, Matthew R. Jones, Patrick Z. El‐Khoury
Abstract
We record nanoscale-resolved chemical images of thiobenzonitrile (TBN)-functionalized smooth gold nanospheres on silicon via tip-enhanced Raman (TER) nanospectroscopy. The recorded images trace the nascence of the familiar doughnut-shaped scattering profile of nanoparticles on silicon at its origin (the particle surface), which appears as a horseshoe-shaped scattering pattern under our experimental conditions. The local optical field maps are in agreement with their simulated finite-difference time-domain analogues. Analysis of the recorded spectra with the aid of ab-initio-molecular-dynamics-based Raman spectral simulations further suggests that optical rectification and molecular charging take place throughout the course of atomic-force-microscopy-based TER nanoscale chemical imaging.