Single-molecule-resolution ultrafast near-field optical microscopy via plasmon lifetime extension

Metal nanostructures support plasmon oscillations on their surfaces, which normally decay very quickly. Nevertheless, the lifetime of these oscillations can be extended near a longer lifetime particle, e.g., a molecule. We utilize this phenomenon for ultrahigh (single-molecule) resolution ultrafast apertureless (scattering) applications. We demonstrate the phenomenon with the numerical solutions of 3D Maxwell equations. We use a nm-sized quantum emitter (QE) for the long lifetime particle. We place the QE at the apex of a metal-coated atomic force microscope tip. We illuminate the tip with a femtosecond laser. The near-field on the metal apex decays quickly. After some time, one receives the scattering signal only from the vicinity of the QE. Thus, the resolution becomes single-QE size. We propose the use of a stress-induced defect center in a 2D material as the QE. The tip indentation of the 2D material, transferred to the tip, originates a defect center located right at the sharpest point of the tip, which is exactly at its apex. Our method can equally be facilitated for single-molecule-size chemical manipulation.