Chemical reactions are complex. Even if only a few molecules are involved, the final configuration will depend on a huge number of parameters – including, in principle, all the possible locations each electron in each atom can occupy as the reaction takes place. Calculating these trajectories is beyond the power of today’s best computers, but researchers led by Kang-Kuen Ni of Harvard University in the US have now demonstrated an alternative. By cooling molecules of potassium and rubidium down to a fraction of a degree above absolute zero, they reduced the number of possible reaction outcomes to just 57. They then probed all these outcomes down to the level of individual quantum states, paving the way for a better understanding of chemistry.
