Principle

Approaching a very sharp metal tip to an electrically conductive sample by applying a electrical field leads to a current between tip and sample without any mechanical contact. This so-called tunneling current is used to investigate the electronic topography on the sub nanometer scale of a fresh prepared graphite (HOPG) surface. By scanning the tip line by line across the surface graphite atoms and the hexagonal structure are imaged.

Benefits


Observe atoms within minutes

Custom-designed for use in teaching labs

Microscope consists of one compact, portable instrument, no additional instruments required

Vibration-isolated for better and reproducible results

Can be used both for imaging of atomic resolution and for spectroscopy

Additional experiment with gold sample can be performed

With interactive teaching and learning software


Tasks


Prepare a Pt-Ir tip and the graphite (HOPG) sample and approach the tip to the sample.

Investigate the topography of clean terraces and the step height between neighboring terraces in constant-current mode.

Image the arrangement of graphite atoms on a clean terrace by optimizing tunneling and scanning parameters. Interpret  the structure by analyzing angles and distances between atoms and atomic rows and by using the 2D and 3D graphite model.

Measure and compare images in the constant-height and constant-current modes.


What you can learn about


Tunneling effect

Hexagonal structures

Scanning Tunneling Microscopy (STM)

Imaging on the sub nanometer scale

Piezo-electric devices

Local Density Of States (LDOS)

Constant-Height-Mode 

Constant-Current-Mode


Software included. Computer not provided.