Feasibility of using LSPR on the biased nanotip to realize the atomic-resolution near-field optical detection

Abstract

A near-field optical detection method and its theoretical model are developed, which follow from an algebra-based conclusion: in the localized surface plasmon resonance (LSPR) region, the extinction coefficient of a metal nanosphere is the sesquiplicate proportion of the localized electron density. Eleven spectral tests of gold, silver, and aluminum nanospheres are used to verify this model. For a metal nanosphere, the frequency and intensity of the LSPR are dependent on the localized electron density only. The electron density can be tuned by adjusting the bias voltage, so the bias can enhance or inhibit the LSPR frequency of the metal nanosphere.