Fig. 1: STM-EL characterisation of phthalocyanines and high-resolution spectra of their cations.
From: Evidence of exciton-libron coupling in chirally adsorbed single molecules
a Scheme of the STM-EL measurement of the MgPc, H2Pc, ZnPc molecules (from top to bottom, respectively), performing in-plane librations on the surface of NaCl/Ag. The red arrow denotes small-energy librations while the grey arrow represents switching between two degenerate chiral equilibrium adsorption positions. b–d Overview STM-EL spectra of the ZnPc, MgPc and H2Pc at −2.8 V, 100 pA, showing the neutral (Q, Qx, Qy) and cation (Q+, Qy+) emission fingerprints plotted with blue solid lines. Grey-filled spectra on the background of each panel are the responses of the nanocavities measured on a clean Ag(111) surface at 2.5 V, 1 nA. e–g Spectra measured at the same bias and tunnelling current with 400 μeV resolution on the ZnPc, MgPc and H2Pc cations, respectively, evidencing the fine structure present in the first two cases. The scale is given relative to the peaks within the spectral manifold, which manifest lower intensity with respect to their neighbours. The reference energies E00 are set to the assumed zero phonon lines in each spectrum. All molecular spectra in b–g are normalised by dividing by their corresponding plasmonic background. Raw spectra are presented in Supplementary Fig. 2. Source data are provided as a Source Data file.
