PostScience debunks scientific myths and explains common misconceptions. We asked our experts to comment on popular ideas about the structure and properties of atoms.

Rutherford's model corresponds to modern ideas about the structure of the atom

This is true, but in part. The planetary model of the atom, in which light electrons revolve around a heavy nucleus, like the planets around the Sun, was proposed by Ernest Rutherford in 1911, after the nucleus itself was discovered in his laboratory. By bombarding a sheet of metal foil with alpha particles, the scientists found that the vast majority of the particles passed through the foil like light through glass. However, a small part of them - about one in 8000 - was reflected back to the source. Rutherford explained these results by the fact that the mass is not uniformly distributed in matter, but is concentrated in "clumps" - atomic nuclei that carry a positive charge that repels positively charged alpha particles. The light, negatively charged electrons avoid "falling" into the nucleus by spinning around them, so that the centrifugal force balances the electrostatic attraction.

After inventing this model, Rutherford is said to have exclaimed, "Now I know what an atom looks like!" However, soon, following the inspiration, Rutherford realized the inferiority of his idea. Rotating around the nucleus, the electron creates around itself alternating electric and magnetic fields. These fields propagate at the speed of light in the form of an electromagnetic wave. And such a wave carries energy with it! It turns out that, rotating around the nucleus, the electron will continuously lose energy and fall on the nucleus within billionths of a second. (One might ask if the same argument could not be applied to the planets of the solar system: why don't they fall on the Sun? Answer: gravitational waves, if they exist at all, are much weaker than electromagnetic waves, and the energy stored in the planets is much greater than in electrons, so the "power reserve" of the planets is many orders of magnitude longer.)

Rutherford instructed his collaborator, the young theoretician Niels Bohr, to resolve the contradiction. After working for two years, Bohr found a partial solution. He postulated that among the possible orbits of an electron, there are those on which the electron can stay for a long time without radiating. An electron can move from one stationary orbit to another, while absorbing or emitting a quantum of an electromagnetic field with an energy equal to the energy difference between the two orbits. Using the initial principles of quantum physics, which had already been discovered by that time, Bohr was able to calculate the parameters of stationary orbits and, accordingly, the energies of radiation quanta corresponding to transitions. These energies had by that time been measured using spectroscopy methods, and Bohr's theoretical predictions almost perfectly matched the results of these measurements!

Despite this triumphant result, Bohr's theory hardly brought clarity to the question of the physics of the atom, because it was semi-empirical: postulating the existence of stationary orbits, it did not explain their physical nature in any way. A deep explanation of the issue required at least another two decades, during which quantum mechanics was developed as a systematic, integral physical theory.

Within the framework of this theory, the electron is subject to the uncertainty principle and is described not by a material point, like a planet, but by a wave function “smeared” over the entire orbit. At each moment of time, it is in a superposition of states corresponding to all points of the orbit. Since the distribution density of mass in space, determined by the wave function, does not depend on time, no alternating electromagnetic field is created around the electron; there is no energy loss.

Thus, the planetary model gives a correct visual representation of what an atom looks like - Rutherford was right in his exclamation. However, it does not provide an explanation of how the atom works: this device is much more complex and deeper, something that Rutherford modeled.

In conclusion, I note that the “myth” about the planetary model is at the very center of the intellectual drama that gave rise to a turning point in physics a hundred years ago and to a large extent shaped this science in its modern form.

Alexander Lvovsky

PhD in Physics, Professor at the Faculty of Physics at the University of Calgary, Head of the Scientific Group, Member of the Scientific Council of the Russian Quantum Center, Editor of the scientific journal Optics Express

Individual atoms can be manipulated

This is true. Of course you can, why not? You can control different parameters of the atom, and the atom has a lot of them: it has a position in space, speed, and there are also internal degrees of freedom. The internal degrees of freedom determine the magnetic and electrical properties of an atom, as well as its readiness to emit light or radio waves. Depending on the internal state of the atom, it can be more or less active in collisions and chemical reactions, change the properties of the surrounding atoms, and its response to external fields also depends on its internal state. In medicine, for example, the so-called polarized gases are used to build tomograms of the lungs - in such gases, all atoms are in the same internal state, which makes it possible to “see” the volume they fill by their response.

It is not so difficult to control the speed of an atom or its position, it is much more difficult to select exactly one atom for control. But this can also be done. One of the approaches to such isolation of an atom is implemented with the help of laser cooling. For control, it is always convenient to have a known initial position, it is quite good if the atom does not move at the same time. Laser cooling makes it possible to achieve both, to localize atoms in space and cool them, that is, to reduce their speed to almost zero. The principle of laser cooling is the same as that of a jet aircraft, only the latter emits a jet of gas to accelerate, and in the first case, the atom, on the contrary, absorbs a stream of photons (light particles) and slows down. Modern laser cooling techniques can cool millions of atoms to walking speeds and below. Further, various kinds of passive traps come into play, for example, a dipole trap. If a light field is used for laser cooling, which the atom actively absorbs, then to keep it in the dipole trap, the light frequency is selected away from any absorption. It turns out that highly focused laser light is able to polarize small particles and dust particles and draw them into the region of the highest light intensity. The atom is no exception and is also drawn into the region of the strongest field. It turns out that if the light is focused as strongly as possible, then only exactly one atom can stay in such a trap. The fact is that if the second gets into the trap, then it is so strongly pressed against the first that they form a molecule and at the same time fall out of the trap. However, such sharp focusing is not the only way to isolate a single atom, you can also use the properties of the interaction of an atom with a resonator for charged atoms, ions, you can use electric fields to capture and hold exactly one ion, and so on. It is possible to completely excite one atom in a rather limited ensemble of atoms into a very highly excited, so-called Rydberg state. An atom, once excited into a Rydberg state, blocks the possibility of excitation of its neighbors into the same state and, if the volume with atoms is small enough, will be the only one.

One way or another, after the atom is caught, it can be controlled. The internal state can be changed by light and radio frequency fields, using the desired frequencies and polarization of the electromagnetic wave. It is possible to transfer an atom to any predetermined state, be it a certain state - a level or their superposition. The only question is the availability of the necessary frequencies and the ability to make sufficiently short and powerful control pulses. Recently, it has become possible to more effectively control atoms by keeping them in the vicinity of nanostructures, which allows not only to "talk" with the atom more efficiently, but also to use the atom itself - more precisely, its internal states - to control light flows, and in the future, perhaps , and for computational purposes.

Controlling the position of the atom held by the trap is quite a simple task - it is enough to move the trap itself. In the case of a dipole trap, move the beam of light, which can be done, for example, with moving mirrors for a laser show. Speed ​​can be given to an atom again in a reactive way - to make it absorb light, and an ion can be easily dispersed by electric fields, just as it was done in cathode ray tubes. So today, in principle, anything can be done with the atom, it is only a matter of time and effort.

Alexey Akimov

Atom is indivisible

Partly true, partly not. Wikipedia gives us the following definition: “Atom (from other Greek ἄτομος - indivisible, uncut) is a particle of matter of microscopic size and mass, the smallest part of a chemical element, which is the carrier of its properties. An atom is made up of an atomic nucleus and electrons.

Now any educated person represents the atom in Rutherford's model, succinctly represented by the last sentence of this generally accepted definition. It would seem that the answer to the question/myth is obvious: the atom is a composite and complex object. However, the situation is not so clear cut. Ancient philosophers invested in the definition of the atom rather the meaning of the existence of an elementary and indivisible particle of matter and hardly connected the problem with the structure of the elements of the periodic table. In Rutherford's atom, we really find such a particle - this is an electron.

Electron in accordance with modern concepts that fit into the so-called

«> Standard Model, is a point, the state of which is described by position and speed. It is important that the simultaneous assignment of these kinematic characteristics is impossible due to the Heisenberg uncertainty principle, but considering only one of them, for example, the coordinate, it can be determined with arbitrarily high accuracy.

Is it then possible, using modern experimental techniques, to try to localize an electron on a scale much smaller than the atomic size (~0.5 * 10-8 cm) and check its punctiformity? It turns out that when trying to localize an electron on the scale of the so-called Compton wavelength - about 137 times smaller than the size of a hydrogen atom - the electron will interact with its antimatter and the system will become unstable.

The point and indivisibility of the electron and other elementary particles of matter is a key element of the principle of short-range action in field theory and is present in all fundamental equations that describe nature. Thus, the ancient philosophers were not so far from the truth, assuming that indivisible particles of matter exist.

Dmitry Kupriyanov

Doctor of Physical and Mathematical Sciences, Professor of Physics, St. Petersburg State Polytechnic University, Head. Department of Theoretical Physics, St. Petersburg State Pedagogical University

Science does not know this yet. The planetary model of the atom, proposed by Rutherford, assumed that electrons revolve around the atomic nucleus, like planets revolving around the sun. In this case, it was natural to assume that electrons are solid spherical particles. Rutherford's classical model was self-contradictory. With all evidence, moving accelerated charged particles (electrons) would have to lose energy due to electromagnetic radiation and eventually fall on the nuclei of atoms.

Niels Bohr proposed to ban this process and introduce certain requirements for the radii of the orbits along which electrons move. Bohr's phenomenological model gave way to the quantum model of the atom developed by Heisenberg and the quantum but more visual model of the atom proposed by Schrödinger. In the Schrödinger model, electrons are no longer balls flying in orbit, but standing waves that, like clouds, hang over the atomic nucleus. The shape of these "clouds" was described by the wave function introduced by Schrödinger.

The question immediately arose: what is the physical meaning of the wave function? The answer was suggested by Max Born: the square of the modulus of the wave function is the probability of finding an electron at a given point in space. And here the difficulties began. The question arose: what does it mean to find an electron at a given point in space? Shouldn't Born's statement be understood as an admission that an electron is a small ball that flies along a certain trajectory and which can be caught at a certain point on this trajectory with some probability?

It was this point of view that Schrödinger and Albert Einstein, who joined him in this matter, adhered to. They were objected to by the physicists of the Copenhagen School - Niels Bohr and Werner Heisenberg, who argued that between the acts of measurement the electron simply does not exist, which means that it makes no sense to talk about the trajectory of its movement. The discussion between Bohr and Einstein about the interpretation of quantum mechanics has gone down in history. Bohr seemed to be the winner: he managed, although not very clearly, to refute all the paradoxes formulated by Einstein, and even the famous “Schrödinger’s cat” paradox formulated by Schrödinger in 1935. For several decades, most physicists agreed with Bohr that matter is not an objective reality given to us in sensations, as Karl Marx taught, but something that arises only at the moment of observation and does not exist without an observer. Interestingly, in Soviet times, philosophy departments in universities taught that such a point of view is subjective idealism, that is, a trend that runs counter to objective materialism - the philosophy of Marx, Engels, Lenin and Einstein. At the same time, at the departments of physics, students were taught that the concepts of the Copenhagen school were the only correct ones (perhaps because the most famous Soviet theoretical physicist, Lev Landau, belonged to this school).

At the moment, the opinions of physicists are divided. On the one hand, the Copenhagen interpretation of quantum mechanics continues to be popular. Attempts to experimentally test the validity of this interpretation (for example, the successful test of the so-called Bell's inequality by the French physicist Alain Aspe) enjoy almost unanimous approval from the scientific community. On the other hand, theorists quite calmly discuss alternative theories, such as the theory of parallel worlds. Returning to the electron, we can say that its chances of remaining a billiard ball are not very high yet. At the same time, they are different from zero. In the 1920s, it was the billiard model of Compton scattering that made it possible to prove that light consists of quanta - photons. In many problems related to important and useful devices (diodes, transistors), it is convenient to consider an electron as a billiard ball. The wave nature of an electron is important for describing more subtle effects, such as the negative magnetoresistance of metals.

The philosophical question of whether there is a ball-electron between the acts of measurement is of little importance in ordinary life. However, this question continues to be one of the most serious problems of modern physics.

Alexey Kavokin

PhD in Physics and Mathematics, Professor at the University of Southampton, Head of the Quantum Polaritonics Group of the Russian Quantum Center, Scientific Director of the Mediterranean Institute of Fundamental Physics (Italy)

An atom can be completely destroyed

This is true. Break not build. Anything can be destroyed, including the atom, with any degree of completeness. An atom in the first approximation is a positively charged nucleus surrounded by negatively charged electrons. The first destructive action that can be performed on an atom is to strip electrons from it. This can be done in different ways: you can focus powerful laser radiation on it, you can irradiate it with fast electrons or other fast particles. An atom that has lost some of its electrons is called an ion. It is in this state that atoms are in the Sun, where the temperatures are so high that it is practically impossible for atoms to save their electrons in collisions.

The more electrons an atom has lost, the harder it is to pull off the rest. An atom has more or less electrons depending on its atomic number. The hydrogen atom generally has one electron, and it often loses it even under normal conditions, and it is hydrogen that has lost its electrons that determines the pH of water. The helium atom has two electrons, and in a fully ionized state is called alpha particles - such particles we already expect more from a nuclear reactor than from ordinary water. Atoms containing many electrons require even more energy to remove all the electrons, but nevertheless, it is possible to remove all the electrons from any atom.

If all the electrons are torn off, then the nucleus remains, but it can also be destroyed. The nucleus consists of protons and neutrons (generally hadrons), and although they are quite strongly bound, an incident particle of sufficient energy can tear them apart. Heavy atoms, in which there are too many neutrons and protons, tend to fall apart on their own, releasing quite a lot of energy - nuclear power plants are based on this principle.

But after all, even if the nucleus is broken, all the electrons are torn off, the original particles remain: neutrons, protons, electrons. Of course, they can also be destroyed. Actually, this is what it does, which accelerates protons to huge energies, completely destroying them in collisions. In this case, many new particles are born, which are studied by the collider. The same can be done with electrons, and with any other particles.

The energy of the destroyed particle does not disappear, it is distributed among other particles, and if there are enough of them, then it becomes impossible to quickly trace the original particle in the sea of ​​new transformations. Everything can be destroyed, there are no exceptions.

Alexey Akimov

Candidate of Physical and Mathematical Sciences, Head of the Quantum Simulators Group of the Russian Quantum Center, Lecturer at the Moscow Institute of Physics and Technology, Fellow of the Lebedev Institute, Researcher at Harvard University

Hydrogen atom capturing electron clouds. And although modern physicists can even determine the shape of a proton with the help of accelerators, the hydrogen atom, apparently, will remain the smallest object, the image of which makes sense to call a photograph. "Lenta.ru" presents an overview of modern methods of photographing the microworld.

Strictly speaking, there is almost no ordinary photography left these days. Images that we habitually call photographs and can be found, for example, in any Lenta.ru photo essay, are actually computer models. A photosensitive matrix in a special device (traditionally it is still called a “camera”) determines the spatial distribution of light intensity in several different spectral ranges, the control electronics stores this data in digital form, and then another electronic circuit, based on this data, gives a command to the transistors in the liquid crystal display . Film, paper, special solutions for their processing - all this has become exotic. And if we remember the literal meaning of the word, then photography is “light painting”. So what to say that the scientists succeeded to photograph an atom, is possible only with a fair amount of conventionality.

More than half of all astronomical images have long been taken by infrared, ultraviolet and X-ray telescopes. Electron microscopes irradiate not with light, but with an electron beam, while atomic force microscopes scan the relief of the sample with a needle. There are X-ray microscopes and magnetic resonance imaging scanners. All these devices give us accurate images of various objects, and despite the fact that it is, of course, not necessary to speak of "light painting" here, we still allow ourselves to call such images photographs.

Experiments by physicists to determine the shape of a proton or the distribution of quarks inside particles will remain behind the scenes; our story will be limited to the scale of atoms.

Optics never get old

As it turned out in the second half of the 20th century, optical microscopes still have room to develop. A decisive moment in biological and medical research was the emergence of fluorescent dyes and methods that allow selective labeling of certain substances. It wasn't "just new paint", it was a real revolution.

Contrary to common misconception, fluorescence is not a glow in the dark at all (the latter is called luminescence). This is the phenomenon of absorption of quanta of a certain energy (say, blue light) followed by the emission of other quanta of lower energy and, accordingly, a different light (when blue is absorbed, green will be emitted). If you put in a filter that allows only the quanta emitted by the dye to pass through and blocks the light that causes fluorescence, you can see a dark background with bright spots of dyes, and dyes, in turn, can color the sample extremely selectively.

For example, you can color the cytoskeleton of a nerve cell red, highlight the synapses in green, and highlight the nucleus in blue. You can make a fluorescent label that will allow you to detect protein receptors on the membrane or molecules synthesized by the cell under certain conditions. The method of immunohistochemical staining has revolutionized biological science. And when genetic engineers learned how to make transgenic animals with fluorescent proteins, this method experienced a rebirth: mice with neurons painted in different colors became a reality, for example.

In addition, engineers came up with (and practiced) a method of so-called confocal microscopy. Its essence lies in the fact that the microscope focuses on a very thin layer, and a special diaphragm cuts off the light created by objects outside this layer. Such a microscope can sequentially scan a sample from top to bottom and obtain a stack of images, which is a ready-made basis for a three-dimensional model.

The use of lasers and sophisticated optical beam control systems has made it possible to solve the problem of dye fading and drying of delicate biological samples under bright light: the laser beam scans the sample only when it is necessary for imaging. And in order not to waste time and effort on examining a large preparation through an eyepiece with a narrow field of view, the engineers proposed an automatic scanning system: you can put a glass with a sample on the object stage of a modern microscope, and the device will independently capture a large-scale panorama of the entire sample. At the same time, in the right places, he will focus, and then glue many frames together.

Some microscopes can accommodate live mice, rats, or at least small invertebrates. Others give a slight increase, but are combined with an X-ray machine. To eliminate vibration interference, many are mounted on special tables weighing several tons indoors with a carefully controlled microclimate. The cost of such systems exceeds the cost of other electron microscopes, and competitions for the most beautiful frame have long become a tradition. In addition, the improvement of optics continues: from the search for the best types of glass and the selection of optimal lens combinations, engineers have moved on to ways to focus light.

We have specifically listed a number of technical details in order to show that progress in biological research has long been associated with progress in other areas. If there were no computers capable of automatically counting the number of stained cells in several hundred photographs, supermicroscopes would be of little use. And without fluorescent dyes, all millions of cells would be indistinguishable from each other, so it would be almost impossible to follow the formation of new ones or the death of old ones.

In fact, the first microscope was a clamp with a spherical lens attached to it. An analogue of such a microscope can be a simple playing card with a hole made in it and a drop of water. According to some reports, such devices were used by gold miners in Kolyma already in the last century.

Beyond the diffraction limit

Optical microscopes have a fundamental drawback. The fact is that it is impossible to restore the shape of those objects that turned out to be much smaller than the wavelength from the shape of light waves: you can just as well try to examine the fine texture of the material with your hand in a thick welding glove.

The limitations created by diffraction have been partly overcome, and without violating the laws of physics. Two circumstances help optical microscopes dive under the diffraction barrier: the fact that during fluorescence quanta are emitted by individual dye molecules (which can be quite far apart from each other), and the fact that by superimposing light waves it is possible to obtain a bright spot with a diameter smaller than wavelength.

When superimposed on each other, light waves are able to cancel each other out, therefore, the illumination parameters of the sample are such that the smallest possible area falls into the bright region. In combination with mathematical algorithms that can, for example, remove ghosting, such directional lighting provides a dramatic improvement in image quality. It becomes possible, for example, to examine intracellular structures with an optical microscope and even (combining the described method with confocal microscopy) to obtain their three-dimensional images.

Electron microscope before electronic instruments

In order to discover atoms and molecules, scientists did not have to look at them - molecular theory did not need to see the object. But microbiology became possible only after the invention of the microscope. Therefore, at first, microscopes were associated precisely with medicine and biology: physicists and chemists who studied much smaller objects managed by other means. When they also wanted to look at the microcosm, diffraction limitations became a serious problem, especially since the methods of fluorescence microscopy described above were still unknown. And there is little sense in increasing the resolution from 500 to 100 nanometers if the object to be considered is even less!

Knowing that electrons can behave both as a wave and as a particle, physicists from Germany created an electron lens in 1926. The idea underlying it was very simple and understandable to any schoolchild: since the electromagnetic field deflects electrons, it can be used to change the shape of the beam of these particles by pulling them in different directions, or, on the contrary, to reduce the diameter of the beam. Five years later, in 1931, Ernst Ruska and Max Knoll built the world's first electron microscope. In the device, the sample was first illuminated by an electron beam, and then the electron lens expanded the beam that passed through before it fell on a special luminescent screen. The first microscope only gave a magnification of 400 times, but the replacement of light with electrons opened the way to photographing with magnification hundreds of thousands of times: the designers had only to overcome a few technical obstacles.

The electron microscope made it possible to examine the structure of cells in a quality that was previously unattainable. But from this picture it is impossible to understand the age of the cells and the presence of certain proteins in them, and this information is very necessary for scientists.

Electron microscopes now allow close-up photographs of viruses. There are various modifications of devices that allow not only to shine through thin sections, but also to consider them in "reflected light" (in reflected electrons, of course). We will not talk in detail about all the options for microscopes, but we note that recently researchers have learned how to restore an image from a diffraction pattern.

Touch, not see

Another revolution came at the expense of a further departure from the principle of "illuminate and see." An atomic force microscope, as well as a scanning tunneling microscope, no longer shines on the surface of the samples. Instead, a particularly thin needle moves across the surface, which literally bounces even on bumps the size of a single atom.

Without going into the details of all such methods, we note the main thing: the needle of a tunneling microscope can not only be moved along the surface, but also used to rearrange atoms from place to place. This is how scientists create inscriptions, drawings and even cartoons in which a drawn boy plays with an atom. A real xenon atom dragged by the tip of a scanning tunneling microscope.

It is called a tunneling microscope because it uses the effect of tunneling current flowing through the needle: electrons pass through the gap between the needle and the surface due to the tunneling effect predicted by quantum mechanics. This device requires a vacuum to operate.

The atomic force microscope (AFM) is much less demanding on environmental conditions - it can (with a number of limitations) work without air pumping. In a sense, the AFM is the nanotech successor to the gramophone. A needle mounted on a thin and flexible cantilever bracket ( cantilever and there is a “bracket”), moves along the surface without applying voltage to it and follows the relief of the sample in the same way as the gramophone needle follows along the grooves of a gramophone record. The bending of the cantilever causes the mirror fixed on it to deviate, the mirror deflects the laser beam, and this makes it possible to very accurately determine the shape of the sample under study. The main thing is to have a fairly accurate system for moving the needle, as well as a supply of needles that must be perfectly sharp. The radius of curvature at the tips of such needles may not exceed one nanometer.

AFM allows you to see individual atoms and molecules, but, like a tunneling microscope, it does not allow you to look under the surface of the sample. In other words, scientists have to choose between being able to see atoms and being able to study the entire object. However, even for optical microscopes, the insides of the studied samples are not always accessible, because minerals or metals usually transmit light poorly. In addition, there are still difficulties with photographing atoms - these objects appear as simple balls, the shape of electron clouds is not visible in such images.

Synchrotron radiation, which occurs during the deceleration of charged particles dispersed by accelerators, makes it possible to study the petrified remains of prehistoric animals. By rotating the sample under X-rays, we can get three-dimensional tomograms - this is how, for example, the brain was found inside the skull of fish that became extinct 300 million years ago. You can do without rotation if the registration of the transmitted radiation is by fixing the x-rays scattered due to diffraction.

And this is not all the possibilities that X-rays open up. When irradiated with it, many materials fluoresce, and the chemical composition of the substance can be determined by the nature of the fluorescence: in this way, scientists color the ancient artifacts, the works of Archimedes erased in the Middle Ages, or the color of the feathers of long-extinct birds.

Posing atoms

Against the backdrop of all the possibilities provided by X-ray or optical fluorescence methods, a new way of photographing individual atoms no longer seems like such a big breakthrough in science. The essence of the method that made it possible to obtain the images presented this week is as follows: electrons are plucked from ionized atoms and sent to a special detector. Each act of ionization strips an electron from a certain position and gives one point on the "photo". Having accumulated several thousand such points, the scientists formed a picture showing the most likely places for finding an electron around the nucleus of an atom, and this, by definition, is an electron cloud.

In conclusion, let's say that the ability to see individual atoms with their electron clouds is more like a cherry on the cake of modern microscopy. It was important for scientists to study the structure of materials, to study cells and crystals, and the development of technologies resulting from this made it possible to reach the hydrogen atom. Anything less is already the sphere of interest of specialists in elementary particle physics. And biologists, materials scientists and geologists still have room to improve microscopes even with a rather modest magnification compared to atoms. Experts in neurophysiology, for example, have long wanted to have a device that can see individual cells inside a living brain, and the creators of rovers would sell their souls for an electron microscope that would fit on board a spacecraft and could work on Mars.

However, photographing the atom itself, and not any part of it, was an extremely difficult task, even with the most high-tech devices.

The fact is that according to the laws of quantum mechanics, it is impossible to equally accurately determine all the properties of a subatomic particle. This section of theoretical physics is built on the Heisenberg uncertainty principle, which states that it is impossible to measure the coordinates and momentum of a particle with the same accuracy - accurate measurements of one property will certainly change data about the other.

Therefore, instead of determining the location (particle coordinates), quantum theory proposes to measure the so-called wave function.

The wave function works in much the same way as a sound wave. The only difference is that the mathematical description of a sound wave determines the movement of molecules in the air in a certain place, and the wave function describes the probability of a particle appearing in one place or another according to the Schrödinger equation.

Measuring the wave function is also not easy (direct observations cause it to collapse), but theoretical physicists can roughly predict its values.

It is possible to experimentally measure all the parameters of the wave function only if it is collected from separate destructive measurements carried out on completely identical systems of atoms or molecules.

Physicists from the Dutch research institute AMOLF have presented a new method that does not require any "rebuilding" and published the results of their work in the journal Physical Review Letters. Their methodology is based on a 1981 hypothesis by three Soviet theoretical physicists, as well as on more recent research.

During the experiment, the team of scientists directed two laser beams at hydrogen atoms placed in a special chamber. As a result of such an impact, the electrons left their orbits at the speed and in the direction that were determined by their wave functions. A strong electric field in the chamber, where the hydrogen atoms were located, sent electrons to certain parts of the planar (flat) detector.

The position of the electrons hitting the detector was determined by their initial velocity, not by their position in the chamber. Thus, the distribution of electrons on the detector told scientists about the wave function of these particles, which they had when they left the orbit around the nucleus of the hydrogen atom.

The movements of the electrons were displayed on a phosphorescent screen in the form of dark and light rings, which the scientists photographed with a high-resolution digital camera.

"We are very pleased with our results. Quantum mechanics has so little to do with people's daily lives that hardly anyone would have thought of getting a real photograph of quantum interactions in the atom," says Aneta Stodolna, lead author of the study. She also claims that the developed technique can also have practical applications, for example, to create conductors an atom thick, to develop the technology of molecular wires, which will significantly improve modern electronic devices.

“It is noteworthy that the experiment was carried out on hydrogen, which is both the simplest and most common substance in our Universe. It will be necessary to understand whether this technique can be applied to more complex atoms. If so, then this is a big breakthrough that will allow us to develop not only electronics, but also nanotechnology,” says Jeff Lundeen of the University of Ottawa, who was not involved in the study.

However, the scientists themselves who conducted the experiment do not think about the practical side of the issue. They believe that their discovery primarily relates to fundamental science, which will help to transfer more knowledge to future generations of physicists.

An atom (from the Greek “indivisible”) is once the smallest particle of matter of microscopic dimensions, the smallest part of a chemical element that bears its properties. The constituents of the atom - protons, neutrons, electrons - no longer have these properties and form them together. Covalent atoms form molecules. Scientists study the features of the atom, and although they are already quite well studied, they do not miss the opportunity to find something new - in particular, in the field of creating new materials and new atoms (continuing the periodic table). 99.9% of the mass of an atom is in the nucleus.

Don't be intimidated by the title. The black hole, accidentally created by the staff of the National Accelerator Laboratory SLAC, turned out to be only one atom in size, so nothing threatens us. And the name "black hole" only remotely describes the phenomenon observed by researchers. We have repeatedly told you about the most powerful X-ray laser in the world, called

Physicists from the United States managed to capture individual atoms in a photo with a record resolution, Day.Az reports with reference to Vesti.ru

Scientists from Cornell University in the United States managed to capture individual atoms in a photo with a record resolution of less than half an angstrom (0.39 Å). Previous photographs had half the resolution - 0.98 Å.

Powerful electron microscopes that can see atoms have been around for half a century, but their resolution is limited by the long wavelength of visible light, which is larger than the diameter of an average atom.

Therefore, scientists use a kind of analogue of lenses that focus and magnify the image in electron microscopes - they are a magnetic field. However, fluctuations in the magnetic field distort the result. To remove distortions, additional devices are used that correct the magnetic field, but at the same time increase the complexity of the electron microscope design.

Previously, physicists at Cornell University developed the Electron Microscope Pixel Array Detector (EMPAD), which replaces a complex system of generators that focus incoming electrons with a single small array of 128x128 pixels that is sensitive to individual electrons. Each pixel registers the angle of electron reflection; knowing it, scientists use ptyicographic techniques to reconstruct the characteristics of the electrons, including the coordinates of the point from which it was released.

Atoms in the highest resolution

David A. Muller et al. Nature, 2018.

In the summer of 2018, physicists decided to improve the quality of the resulting images to a record-breaking resolution to date. Scientists fixed a sheet of 2D material - molybdenum sulfide MoS2 - on a movable beam, and released electron beams by turning the beam at different angles to the electron source. Using EMPAD and ptyicography, scientists determined the distances between individual molybdenum atoms and obtained an image with a record resolution of 0.39 Å.

"In fact, we have created the world's smallest ruler," explains Sol Gruner (Sol Gruner), one of the authors of the experiment. In the resulting image, it was possible to see sulfur atoms with a record resolution of 0.39 Å. Moreover, we even managed to see the place where one such atom is missing (indicated by an arrow).

Sulfur atoms at record resolution