Andrey Geim and Konstantin Novoselov figured out how to make water "dead" and deprive it of its unique dissolving properties, experimenting with the finest "sandwiches" of graphite and boron nitride, according to an article published in the journal Science.
"Dead water" is not just an interesting scientific phenomenon, its discovery has quite specific applications for other sciences, especially biology. It will help us understand why water is so important to the existence of life. Considering the role water plays in the formation of protein molecules, we can say that thin layers of water are sculptors of life in the literal and figurative sense, "says Andrey Geim from the University of Manchester (UK).
Water, as scientists explain, today remains one of the most mysterious substances on Earth. Unlike "neighbors" on the periodic table, the combination of hydrogen with oxygen has an abnormally high boiling and freezing point, unusual heat capacity and the ability to dissolve a huge number of organic and inorganic compounds.
This "skill" of water, in turn, is associated with its other physical property - a high electric dipole moment. By this word, scientists understand how the positive and negative charges are distributed throughout the molecule. Water molecules have a very high dipole moment, since the electrons in it are "attracted" to the oxygen atom, while the positively charged hydrogen atoms, on the contrary, are removed from them.
Scientists have long wondered if it retains these properties in cases where water molecules are stacked in a few layers, or if they change to something completely different.
Game, Novoselov and their university colleagues solved this problem by experimenting with peculiar "sandwiches" assembled from ultrathin graphite plates and two-dimensional boron nitride films, structured in much the same way as graphene, for whose discovery Russian-British physicists received the Nobel Prize in 2010.
Using a sheet of graphite as a "foundation", the scientists laid the boron nitride films on top of it in such a way that they got a kind of "house" with many separate "rooms" in width and height of several tens of nanometers. Thanks to this, a very small number of water molecules could get into such slots, which allowed Geim and his team to very accurately measure their dielectric and other physical properties.
To do this, the scientists brought the needle of a supersensitive atomic force microscope to each such "room" and observed how well the electric field penetrated through the "sandwich" of flat semiconductor materials and water, changing the height and width of this entire structure.
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As shown by these observations, the properties of the liquid changed dramatically if the thickness of its layer approached the mark of two nanometers. In this case, the water became "dead" and lost its amazing dielectric properties and ceased to be a universal solvent.
“We knew that the properties of thin layers of water would be very different from how a 'normal' liquid behaves, but we didn't know how. We were surprised that they were really different, but not in the direction we expected - small amounts of water had an extremely low rather than a high degree of polarization,”adds Laura Fumagalli, a colleague of Geim.
Such a discovery, as noted by the Russian-British physicist, is very important in the context of studying the evolution of life and searching for fellow humans, since thin films from water could play an important role in the evolution of the first complex chemical molecules, including DNA, and in the life of the first inhabitants. Earth.
