7A50.13 STM

The STM has revolutionized the field of surface science.   Real time images with atomic resolution from a sample surface of monolithic graphite is performed in the classroom.

Using computer control a fine pointed tip is brought extremely close to the graphite surface. A voltage is placed between the tip and the sample surface. The sample is electrically conducting.  When the probe tip is very close to the sample surface a tunneling current can exist between the tip and surface. The current flow is very sensitive to the distance between the tip and surface. The tip is  rastered across the surface with the aid of piezo-electric actuators. The current travels between the sample and the tip and is sensed by electronic amplifiers.   In the recent past in order to achieve atomic resolution for most samples the STM had to operate in ultra high vacuum conditions.  But today, due to the development of new techniques it is performed in the classroom at atmospheric pressure.

After the tunneling current is recorded the image is cleaned up using various filtering methods and the image is shown to the class.

http://www.almaden.ibm.com/vis/stm/gallery.html

Edited by JZ on 1/16/05