Turn on Nanolight in a Tiny Gap

A new low-temperature scanning tunneling microscopy technique with laser optics allows for optical excitation and spectroscopy at the level of a single atom or molecule. Shape and material of the microscope's tip prove essential for these investigations; thus, the tip is produced with nanoscale precision by Focused Ion-Beam milling. The localized surface plasmon properties of the tips are engineered by altering the tip structures providing spectral tunability. Local optical excitation is performed by a wavelength-tunable laser source. This tip-enhanced resonance Raman spectroscopy provides a new approach for the atomic-scale optical characterization of local electron-phonon coupling and could ultimately lead to new nanoscale optoelectronic devices with exceptional high sensitivity and efficiency.