Figure 4.
Controllability of resonant tunneling luminescence. Measurements of 2–5 MLs of C60 on Ag(111) at 100 pA constant current, with terrace boundary contours marked in cyan. (a, b) Topography and integrated photon emission efficiency, both at −2.86 V. Efficiency marked γ/e– denoting photons per electron is calculated as light intensity × elementary charge unit/current. (c) Integrated photon emission efficiency at −4.00 V. (d) Differential conductance (dI/dV) spectra on the fourth C60 terrace as a function of relative tip–sample distance. Two LUMO features are visible. (e) The energetic position of the LUMO features as a function of relative tip–sample distance. The lines are a fit to the data points and show that the LUMO features’ positions follow lines of constant electric field.