The scanning tunnelling microscope (STM) uses a process called quantum tunnelling.
Explain what is meant by quantum tunnelling of an electron in an STM.
An STM can be operated in constant-height mode to map the positions of atoms on a sample surface.
Describe how the STM creates a map of the surface in this mode.
The smallest features that an STM can resolve are approximately equal in size to the de Broglie wavelength of the tunnelling electrons.
Deduce whether electrons with kinetic energies of 15 eV15\text{ eV}15 eV are suitable to resolve individual atoms on a surface where the spacing between adjacent atoms is 0.24 nm0.24\text{ nm}0.24 nm.
