Investigating tip-nanoparticle interactions in spatially correlated total internal reflection plasmon spectroscopy and atomic force microscopy

A new approach for achieving spatially correlated localized surface plasmon resonance (LSPR) spectroscopy and atomic force microscopy (AFM) imaging based on through-the-objective white light total internal reflection (TIR) is described. Using this technique, we successfully demonstrate spatially correlated measurements as well as the effect of tip-nanoparticle interactions including the ability to controllably manipulate nanoparticle position. Significant red shifts are observed in the LSPR spectra of single nanoparticles with successive AFM scans in ambient conditions. Identical experiments performed under water conclusively show that the shifts are caused by the small amount of water that collects between the tip and the sample in ambient AFM.