The atom, subject of debate since ancient Greek times, has now arguably achieved the status of an everyday entity. It can be 'seen' and manipulated with a microscope that is becoming commonplace, even in the undergraduate laboratory. Eleven years after Rohrer and Binnig shared the Nobel prize for their invention, the scanning tunnelling microscope is being used routinely by researchers in activities as diverse and interdisciplinary as making living cells 'talk' to silicon chips and studying reactions in solution. There's plenty of room at the bottom . This invention opened the floodgates for imaging almost any material, including biological materials.
Chemists are surer than ever that they are now 'seeing' atoms.
One surface chemist recently told Chemistry in Britain , 'in the past, our forebears worked out things about atoms, structures and surfaces through sheer intellectual effort. We can now actually see the atoms that their theories predicted. The tip, usually made of platinum- iridium or tungsten, tapers to a point that finishes with a single atom, and scans in regular rows at a height of a few nanometres across the surface being investigated. The tip interacts with the surface by an effect known as quantum- mechanical tunnelling which is highly sensitive to distance. The amount of current at a given height from the surface is recorded by computer, giving a contour map.