Fig. 2: Termination-dependent scanning tunneling microscopy and spectroscopy of the CO state.
a Differential conductance dI/dV(r, V = 50 mV) map acquired over the kagome termination, and (b) associated Fourier transform (FT). c Energy-dependent FT linecuts of dI/dV(r, V) maps of the kagome termination, starting at the FT center along the three Γ-K directions (labeled as qa, qb and qc in b). Non-dispersive CO peaks are observed along all three directions. d Energy-dependent FT linecuts of dI/dV(r, V) maps of the Sn2 termination, starting at the FT center along the three Γ-K directions. No additional peaks are observed at the same momentum-transfer position where the CO peaks are seen on the kagome termination. Small vertical arrows above the top panel in (c, d) denote the position where the CO peak is expected. Average dI/dV spectra (solid line and circle symbols) over (e) the kagome and (f) Sn2 termination. Diffuse orange (blue) background shows representative dI/dV spectra taken over several linecuts in the same field-of-view on kagome (Sn2) surface. STM setup conditions: (a) Iset = 50 pA, Vsample = 50 mV, Vexc = 4 mV; (c) Iset = 30 pA, Vsample = –100 mV, Vexc = 5 mV; (d) Iset = 200 pA, Vsample = 50 mV, Iset = 2 mV; (e) Iset = 30 pA, Vsample = 50 pA, Vexc = 3 mV; (f) Iset = 200 pA, Vsample = 50 mV, Vexc = 1 mV. Scale bars correspond to: (a) 4 nm; (b) 1 Å–1.
