17 September 2020
Ultrafast route in water molecules
Published online 3 March 2010
The water molecule is simple in structure. When it is condensed into a solution, however, the interplay between compounds of water molecules opens up a world of interactions. Electronic excitation of these compounds causes a proton transfer from one molecule to its neighbour, resulting in fragmentation.
Researchers from Germany, the United States and Jordan were able to observe directly a different type of fragmentation that occurs on excitation but without proton transfer. This occurs through a process called intermolecular coulombic decay or ICD. It takes place when the molecules are attracted by weak bonds.
Upon excitation of one water molecule by removing an electron, researchers found that another adjacent molecule emitted a low-energy electron, with this also becoming charged. The de-excitation relaxation occurs ultrafast so that there is no time for a proton to move from one molecule to the other before they break apart.
Low-energy electrons have been shown to break up DNA. The electrons released by this phenomenon might thus cause radiation damage in biological systems. The researchers suggest that further experiments using their set-up might determine the effect that this decay channel can have on DNA constituents.
Jahnke, T. et al. Ultrafast energy transfer between water molecules. Nature Phys. 6, 139-142 (2010) | Article |