Electrically-driven vibronic spectroscopy with sub-molecular resolution

TL;DR

This paper demonstrates sub-molecular resolution vibronic spectroscopy using a scanning tunneling microscope to analyze molecular vibrational modes and chemical fingerprints through electroluminescence.

Contribution

It introduces a method for electrically-driven vibronic spectroscopy with sub-molecular spatial resolution, linking vibrational modes to molecular symmetry.

Findings

Identification of vibrational modes via electroluminescence spectra

Sub-molecularly-resolved vibronic maps reveal vibrational symmetry patterns

Correlation between photon emission features and molecular vibrational fingerprints

Abstract

A scanning tunneling microscope is used to generate the electroluminescence of phthalocyanine molecules deposited on NaCl/Ag(111). Photon spectra reveal an intense emission line at 1.9 eV that corresponds to the fluorescence of the molecules, and a series of weaker red-shifted lines. Based on a comparison with Raman spectra acquired on macroscopic molecular crystals, these spectroscopic features can be associated to the vibrational modes of the molecules and provide a detailed chemical fingerprint of the probed species. Maps of the vibronic features reveal sub- molecularly-resolved structures whose patterns are related to the symmetry of the probed vibrational modes.