Electronic Speed-trap

A speed-trap for electrons joyriding through single crystals based on MRI can reveal their velocities and produce an image showing an electron density map of the electrons in the crystal. In a kind of cold-case re-opened, the technique provides new evidence to show that the electrons are not breaking Ohm’s law.

Noam Kaplan of the Hebrew University in Jerusalem and colleagues M Drescher and E Dormann at Karlsruhe University, Germany, have developed a technique to measure electron velocity, separate from the electric current flowing through the material. Current is analogous to measuring the number of cars that pass a speed trap rather than the velocity of individual vehicles. The team used MRI, not to produce an image, but to detect electrons simply by monitoring their spin. To measure electron velocity, however, they scanned the crystal, a radical cation salt, with no current flowing.

You can find out what their experiments revealed in David Bradley’s latest news round-up on spectroscopynow.com