Taking a shine to number 100

Scientists have for the first time literally shed light on properties of the radioactive element fermium–a metal discovered some 50 years ago.

SHOOTING GALLERY. Laser beams that knock electrons off fermium atoms in this chamber reveal traits of the heavy element. A. Zschau

Spectroscopy, or the measurement of the wavelengths of light that materials emit or absorb, is a standard way to probe characteristics of materials, including what energy levels their electrons can assume. However, spectroscopy of heavy elements, such as artificially made fermium, element number 100, is difficult because such substances are scarce and decay soon after they’re made.

Now, Harmut Backe and Norbert Trautmann of the University of Mainz in Germany and their colleagues report using their own particularly sensitive method to measure wavelengths of light absorbed by some of the element’s electrons. The team studied less than 2 billionths of a gram of fermium painstakingly produced by Oak Ridge (Tenn.) National Laboratory and then flown to Germany.

The findings, reported in the April 25 Physical Review Letters, agree with somewhat controversial calculations, based on relativity, by which scientists predicted the wavelengths that fermium’s fast-moving electrons might absorb. Besides probing fermium further, the team plans next to study element number 101, mendelevium, Backe says.


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