An international team of researchers from the Max Plank Institute for Polymer Research of Mainz (Germany), the Catalan Institute of Nanoscience and Nanotechnology (ICN2, Spain) and the University of Manchester (England) has found that water can interact directly with the carbon’s electrons: a quantum phenomenon that is very unusual in fluid dynamics.
A liquid, such as water, is made up of small molecules that randomly move and constantly collide with each other. A solid, in contrast, is made of neatly arranged atoms that are surrounded by a cloud of electrons. The solid and the liquid worlds are assumed to interact only through collisions of the liquid molecules with the solid’s atoms: the liquid molecules do not “see” the solid’s electrons. Nevertheless, just over a year ago, a theoretical study proposed that at the water-carbon interface, the liquid’s molecules and the solid’s electrons push and pull on each other, slowing down the liquid flow: this new effect was called quantum friction. However, the theoretical proposal lacked experimental verification.
The team has used lasers to see quantum friction at work. The team studied a sample of graphene, using ultrashort red laser pulses (with a duration of only a millionth of a billionth of a second) to instantaneously heat up the graphene’s electron cloud. They then monitored its cooling with terahertz laser pulses, which are sensitive to the temperature of the graphene electrons. This technique is called optical pump – terahertz probe (OPTP) spectroscopy.
To the scientists' surprise, the electron cloud cooled faster when the graphene was immersed in water, while immersing the graphene in ethanol made no difference to the cooling rate. They saw this an indication that the water-carbon couple is somehow special, but we still had to understand what exactly was going on. A possible explanation was that the hot electrons push and pull on the water molecules to release some of their heat: in other words, they cool through quantum friction. The researchers delved into the theory, and indeed: water-graphene quantum friction could explain the experimental data.
"It's fascinating to see that the carrier dynamics of graphene keep surprising us with unexpected mechanisms, this time involving solid-liquid interactions with molecules none other than the omnipresent water," comments Prof Klaas-Jan Tielrooij from ICN2 (Spain) and TU Eindhoven. What makes water special here is that its vibrations, called hydrons, are in sync with the vibrations of the graphene electrons, called plasmons, so that the graphene-water heat transfer is enhanced through an effect known as resonance.
The experiments thus confirm the basic mechanism of solid-liquid quantum friction. This will have implications for filtration and desalination processes, in which quantum friction could be used to tune the permeation properties of the nanoporous membranes. “Our findings are not only interesting for physicists, but they also hold potential implications for electrocatalysis and photocatalysis at the solid-liquid interface," says Xiaoqing Yu, PhD student at the Max Planck Institute in Mainz and first author of the work.
The discovery was down to bringing together an experimental system, a measurement tool and a theoretical framework that seldom go hand in hand. The key challenge is now to gain control over the water-electron interaction. “Our dream is to switch quantum friction on and off on demand,” sais study lead author Dr Nikita Kavokine, a researcher at the Max Planck Institute in Mainz and the Flatiron Institute in New York. “This way, we could design smarter water filtration processes, or perhaps even fluid-based computers.”
Consistency of orientation…
Consistency of orientation and movement of graphene platelets in the presence of the Earth's magnetic field
Introduction: Graphene platelets, composed of carbon sheets in a hexagonal lattice, can exhibit unusual behaviors when exposed to the Earth's magnetic field. In particular, orientation coherence and coherent movement of platelets in a common direction were observed.
Experimental context : in a distilled water bath of pyrolytic graphite, once the same has been removed, transparent water remains which, illuminated by a brush of light at a precise angle, shows, under the microscope and by reflection, containing platelets in constant and unidirectional movement in both but the associated verses.
Hypotheses and explanations: A possible explanation of the observed phenomenon is that the plates seen are made of graphene due to their origin and to their total transparency if otherwise illuminated, they show a coherent orientation and a coherent movement in the presence of the earth's magnetic field alone. the same experiment was tried and tested in another site 5 km away. from the first
it is hypothesized that the p-electrons in graphene, which lie above or below the plane of the hexagonal lattice of carbon nuclei, are subject to the Lorenz force in the presence of the Earth's magnetic field. This leads to the enlargement of their orbits all having parallel positions to the graphene lattice and, at the same time, to their reorientation tendentially perpendicular to the earth's magnetic field, to the interaction then of their orbits in the enlargement, to the strengthening of the magnetic field by self-induction given the innumerable p electrons involved and close to the Fermi points, to the distribution of the orbits in a concentrical way, to the folding of the field lines and to the consequent Lorenz forces, this time perpendicular to the plane of the molecular lattice.
These concomitant combinations order electrons and orbits according to a concentric geometry of existence for equilibrium and in a train of electrons planimetrically equidistant from each other both along the orbit and between the orbits This configuration is very similar to the interference figures shown in this article https ://www.pnas.org/doi/full/10.1073/pnas.2110285118 . The phenomenon described by me of movement and equi-orientation of the surfaces has been filmed several times in different fields by me and a friend of mine, the observed platelets move and maintain a unidirectional movement, certainly by non-trivial magnetic forces, acting with the mechanism described and certainly combined with hydraulic resistances that are remarkable by their nature, however, they show a specific position and constant speed. It is important to note that through these hypotheses and the formulation of trains of electrons, searching on google I found the references to the article mentioned here.
the study is in line with my hypotheses which certainly need to be investigated and verified and cast a cascade of other questions in related fields such as superconductivity or the study of stimulated and exploitable magnetic forces.