ULTRACOLD MOLECULES
Whatâ•˙s new-first ever accumulation of molecules in large numbers and
at a temperature near absolute zero. Using lasers to slow a gas of
particles down to near stillness is by now a standard method for
measuring the subtle properties of atoms. Steven Chu, nominated to be
the Secretary of Energy, won a Nobel Prize for pioneering this subject.
Cooling molecules in this same way is difficult since molecules, made of
two or more atoms, have complicated internal motions. But this year
several labs succeeded in first cooling atoms and then, at a temperature
close to absolute zero, getting them to combine into molecules. Labs at
NIST/Colorado (Science, 10 Oct) and at the University of Innsbruck (PRL,
26 Sep) got atoms to pair up into molecules and collect in high
densities at very low temperatures inside traps. The NIST experiment
produces molecules from rubidium and potassium atoms (publication in
Science). Innsbruck researchers first placed rubidium atoms in an
optical lattice before condensing them into molecules.
Background at http://www.aip.org/pnu/2008/split/875-1.html; figure
http://www.aip.org/png/2008/306.htm; PRL text and overview at
http://physics.aps.org/articles/v1/24