Local density of states from spectroscopic scanning-tunneling-microscope images: Ag(111)

Electron scattering from steps on the Ag(111) surface has been studied by scanning tunneling microscopy (STM) and spectroscopic STM images of the differential conductance $\mathrm{}(dI/dV).$ The amplitudes and positions of maxima of $dI/dV$ deviate significantly from those of the local density of states (LDOS). These deviations are due to variations of the vertical tip position which exponentially affect the tunneling barrier transmission and, hence, $dI/dV.\mathrm{}$ We show that the LDOS can be recovered from simultaneous topographic and spectroscopic measurements.