Scientists from the University of Basel in Switzerland found an abnormal property near the water, which is expressed by the fact that some of its molecules (para-isomers) react better than others (ortho isomers).
The water molecule exists in two forms – ortho- (o-) and para-water (p-water), which differ from each other by the value of the total nuclear spin, which is composed of the spins of the hydrogen molecules that make up the molecule. In o-water it is equal to unity, and for p-water it is zero. Spin can not change in isolated molecules, it also persists in collisions with other molecules and even in chemical reactions.
Differences in the spins affect rotational symmetry, so the molecule of p-water will be symmetrical, and o-water – antisymmetric (a complete revolution is needed to return to the initial state). However, up to now it has not been known whether the spins can determine the different chemical properties of o- and p-water.
The researchers created a plasma-dust crystal of calcium and diazenylium ions (N2H +) in an ion trap and traced how different forms of water react with it.
Since the para-isomers deviate more strongly in the electrostatic field due to their significant dipole moment, this allowed scientists to separate the two forms of water from each other. Then the crystal was bombarded with water molecules, and by the number of remaining diazelinium ions, researchers determined which isomer reacted better with the crystal.
It turned out that the rotational symmetry of para- water molecules made them 23 percent more reactive than ortho-water. Thus, it was first demonstrated that the entry into the chemical reaction of polyatomic molecules with ions depends on the rotational symmetry.