Intimate Images Of Electron Orbits
“If you took high school chemistry, then you undoubtedly recall the bizarre drawings of the “orbitals” that describe where in an atom or a molecule an electron is likely to be found.
Resembling strange clouds with multiple lobes, the shapes and orientation of the orbitals control where electrons can go and how molecules can share or exchange them in chemical bonding and interactions.
Now, a team of researchers has taken a key step toward directly measuring the orbitals of molecules lying on a surface, an advance that should let theorists test the results of their high-precision quantum mechanics calculations and could pave the way to designer molecular devices.
To make the breakthrough, a team of physicists at IBM Research Zurich in Switzerland and the University of Liverpool in the United Kingdom used a device called a scanning tunneling microscope (STM).
It consists of a tiny metal finger with a tip only a few atoms wide that moves back and forth just above the surface of a sample.
When scientists apply a voltage to the finger, electrons can hop between it and the surface through a process called quantum tunneling. In the simplest setup, the size of the current reveals the density of electrons in the surface, allowing it to be mapped out.”