Fig. 2: Evolution of dI/dV spectra from monomer to trimer.
a, c, e Normalized differential conductance spectra recorded on the atoms for the monomer a, dimer c, and trimer e and on the bare NbSe2 (gray). Tip gap indicated in gray. Feedback was opened at 250 pA, 5 mV and a modulation of 15 μV was used. In a the α-, β-, γ- and δ-resonances are indicated by black arrows. In c, the split resonances from α and β are indicated by arrows. b, d, f Line profiles recorded along the monomer b, dimer d, and trimer f as illustrated in the topographies (insets; recorded in constant-current mode with set point 100 pA, 10 mV). Horizontal dashed lines serve as guide to the eye for the precise location of the spectra of a, c, e. Vertical white dashed lines indicate 2Δtip. g Zoom to subgap range of f. The α- and β-resonances are indicated by the white dashed lines and labeled above the panels. h Close-up of the oscillatory decay around 1.8 mV as indicated by the box in g.
