Physicists have learned to cool molecules “in one fell swoop”
Scientists were able to cool strontium monofluoride molecules to almost absolute zero “in one fell swoop.” Physicists described the technology they used in an article in the journal Nature. Briefly about the work writes Nature News.
Unlike molecules and atoms at room temperature, a substance cooled to temperatures close to absolute zero (minus 273.15 degrees Celsius, or 0 degrees Kelvin) begins to demonstrate quantum properties (in heated matter they are “clogged” by thermal effects ). Scientists know how to cool atoms down to a few millionths of a Kelvin, but cooling molecules is a much more complicated process.
Physicists often cool atoms using a laser – the atoms absorb photons and then emit them. When this process is repeated many times, the atoms gradually lose their kinetic energy, that is, they cool down. This method has not yet been used for molecules – they are heavier and lose energy worse. In addition, in molecules “extra” energy is stored in the bonds between atoms, as well as in the rotational motions of the molecule as a whole.
In most of the earlier work, atoms were cooled, and then molecules were “assembled” from them. The authors of the new study decided to cool the molecules directly. Scientists have experimented with strontium monofluoride, whose vibrational energy is less than that of many other molecules. In addition, physicists have chosen the color of the laser so that its effect does not cause the molecules to rotate. Finally, the researchers pre-cooled strontium monofluoride in a special way.
As a result, the authors managed to cool the molecules down to 300 microkelvin (microkelvin is one millionth kelvin). Calculations show that the technology used by scientists can lower their temperature to even lower values.