Crystal cold. A computer simulation shows concentric shells of barium-138 ions (blue), other barium isotopes (red), and large molecular ions (green) cooled to less than one-tenth of a degree Kelvin in a radio-frequency ion trap. Large molecules have never been so cool. Image Credit: Phys. Rev. Lett. 97, 243005 (2006)
Physicists have cooled single atoms and molecules with two or three atoms to just a few thousandths of a degree above absolute zero, but it has proved hard to push larger molecules below about 10 degrees Kelvin. Researchers now report cooling large organic molecules to less than 0.1 K using a technique that should also work with proteins and other biomolecules. Temperatures this low will allow scientists to study molecular structures and chemical processes with unprecedented precision and perhaps explore novel issues of fundamental physics.