A scanning tunnelling microscope tip approaches a metal surface of work function

PHYSICS · Subjective · Fermi University Physics · Condensed Matter, Materials & Soft Matter · Crystal structure, bonding and diffraction · Crystal structure, bonding and diffraction

Solid State Physics, Ch Seeing atoms: electron and scanning-probe microscopy

Problem

\phi=4.5\,\mathrm{eV}

. At a fixed bias voltage the tip-sample gap is reduced from

8.0\,\mathrm{\AA}

6.0\,\mathrm{\AA}

. Using

I\propto V e^{-2\kappa d}

with

\kappa=0.512\sqrt{\phi[\mathrm{eV}]}\,\mathrm{\AA^{-1}}

, find the factor by which the tunnel current increases.

Browse the problem library