There are still many possibilities down there. First image of the orbital structure of a hydrogen atom What an atom looks like

However, photographing the atom itself, and not just any part of it, seemed to be an extremely difficult task even when using 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 branch 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 equal precision - accurate measurements of one property will certainly change the data about the other.

Therefore, instead of determining the location (coordinates of the particle), 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 a particular place according to the Schrödinger equation.

Measuring the wave function is also difficult (direct observations lead to its 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 presented a new method that does not require any “rearrangements” and published the results of their work in the journal Physical Review Letters. Their technique is based on a 1981 hypothesis by three Soviet theoretical physicists, as well as more recent research.

During the experiment, a team of scientists directed two laser beams at hydrogen atoms placed in a special chamber. As a result of this impact, the electrons left their orbits at the speed and direction determined by their wave functions. The strong electric field in the chamber containing the hydrogen atoms directed the electrons to specific parts of the planar (flat) detector.

The position of the electrons hitting the detector was determined by their initial velocity, not their position in the chamber. Thus, the distribution of electrons on the detector told scientists about the wave function these particles had when they left orbit around the nucleus of a 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 everyday life that it is unlikely that anyone would have thought of getting a real photograph of quantum interactions in an atom," says lead author Aneta Stodolna. She also claims that the developed technique can also have practical applications, for example, to create conductors as thin as an atom, the development of molecular wire technology, which will significantly improve modern electronic devices.

“It is noteworthy that the experiment was carried out specifically 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 who conducted the experiment themselves do not think about the practical side of the issue. They believe that their discovery primarily relates to fundamental science, which will help pass on more knowledge to future generations of physicists.

As you know, everything material in the Universe consists of atoms. An atom is the smallest unit of matter that carries its properties. In turn, the structure of the atom is made up of a magical trinity of microparticles: protons, neutrons and electrons.

Moreover, each of the microparticles is universal. That is, you cannot find two different protons, neutrons or electrons in the world. They are all absolutely similar to each other. And the properties of the atom will depend only on the quantitative composition of these microparticles in the overall structure of the atom.

For example, the structure of a hydrogen atom consists of one proton and one electron. The next most complex atom, helium, consists of two protons, two neutrons and two electrons. A lithium atom is made up of three protons, four neutrons and three electrons, etc.

Atomic structure (from left to right): hydrogen, helium, lithium

Atoms combine to form molecules, and molecules combine to form substances, minerals, and organisms. The DNA molecule, which is the basis of all living things, is a structure assembled from the same three magical bricks of the universe as the stone lying on the road. Although this structure is much more complex.

Even more amazing facts are revealed when we try to take a closer look at the proportions and structure of the atomic system. It is known that an atom consists of a nucleus and electrons moving around it along a trajectory describing a sphere. That is, it cannot even be called a movement in the usual sense of the word. Rather, the electron is located everywhere and immediately within this sphere, creating an electron cloud around the nucleus and forming an electromagnetic field.

Schematic representations of the structure of an atom

The nucleus of an atom consists of protons and neutrons, and almost all the mass of the system is concentrated in it. But at the same time, the nucleus itself is so small that if its radius is increased to a scale of 1 cm, then the radius of the entire atomic structure will reach hundreds of meters. Thus, everything that we perceive as dense matter consists of more than 99% of the energetic bonds between physical particles and less than 1% of the physical forms themselves.

But what are these physical forms? What are they made of, and how material are they? To answer these questions, let's take a closer look at the structures of protons, neutrons, and electrons. So, we descend one more step into the depths of the microworld - to the level of subatomic particles.

What does an electron consist of?

The smallest particle of an atom is an electron. An electron has mass but no volume. In the scientific concept, an electron does not consist of anything, but is a structureless point.

An electron cannot be seen under a microscope. It is visible only in the form of an electron cloud, which looks like a blurry sphere around the atomic nucleus. At the same time, it is impossible to say with accuracy where the electron is at a moment in time. Instruments are capable of capturing not the particle itself, but only its energy trace. The essence of the electron is not embedded in the concept of matter. It is rather like some empty form that exists only in movement and due to movement.

No structure in the electron has yet been discovered. It is the same point particle as an energy quantum. In fact, an electron is energy, however, it is a more stable form of it than the one represented by photons of light.

At the moment, the electron is considered indivisible. This is understandable, because it is impossible to divide something that has no volume. However, the theory already has developments according to which the electron contains a trinity of such quasiparticles as:

• Orbiton – contains information about the orbital position of the electron;
• Spinon – responsible for spin or torque;
• Holon – carries information about the charge of the electron.

However, as we see, quasiparticles have absolutely nothing in common with matter, and carry only information.

Photographs of atoms of different substances in an electron microscope

Interestingly, an electron can absorb energy quanta, such as light or heat. In this case, the atom moves to a new energy level, and the boundaries of the electron cloud expand. It also happens that the energy absorbed by an electron is so great that it can jump out of the atomic system and continue its movement as an independent particle. At the same time, it behaves like a photon of light, that is, it seems to cease to be a particle and begins to exhibit the properties of a wave. This was proven in an experiment.

Jung's experiment

During the experiment, a stream of electrons was directed at a screen with two slits cut in it. Passing through these slits, the electrons collided with the surface of another projection screen, leaving their mark on it. As a result of this “bombardment” of electrons, an interference pattern appeared on the projection screen, similar to the one that would appear if waves, but not particles, passed through two slits.

This pattern occurs because a wave passing between two slits is divided into two waves. As a result of further movement, the waves overlap each other, and in some areas they are mutually cancelled. The result is many fringes on the projection screen, instead of just one, as would be the case if the electron behaved like a particle.

Structure of the nucleus of an atom: protons and neutrons

Protons and neutrons make up the nucleus of an atom. And despite the fact that the core occupies less than 1% of the total volume, it is in this structure that almost the entire mass of the system is concentrated. But physicists are divided on the structure of protons and neutrons, and at the moment there are two theories.

• Theory No. 1 - Standard

The Standard Model says that protons and neutrons are made up of three quarks connected by a cloud of gluons. Quarks are point particles, just like quanta and electrons. And gluons are virtual particles that ensure the interaction of quarks. However, neither quarks nor gluons were ever found in nature, so this model is subject to severe criticism.

• Theory #2 - Alternative

But according to the alternative theory of the unified field, developed by Einstein, the proton, like the neutron, like any other particle of the physical world, is an electromagnetic field rotating at the speed of light.

Electromagnetic fields of man and planet

What are the principles of atomic structure?

Everything in the world - thin and dense, liquid, solid and gaseous - is just the energy states of countless fields that permeate the space of the Universe. The higher the energy level in the field, the thinner and less perceptible it is. The lower the energy level, the more stable and tangible it is. The structure of the atom, as well as the structure of any other unit of the Universe, lies in the interaction of such fields - different in energy density. It turns out that matter is just an illusion of the mind.

In fact, the author of the RTCh has gone so far in his “reflections” that it is time to provoke a heavy counter-argumentation, namely, data from an experiment by Japanese scientists to photograph the hydrogen atom, which became known on November 4, 2010. The image clearly shows the atomic shape, confirming both the discreteness and roundness of atoms: “A group of scientists and specialists from the University of Tokyo photographed for the first time in the world an individual hydrogen atom - the lightest and smallest of all atoms, news agencies report.

The picture was taken using one of the latest technologies - a special scanning electron microscope. Using this device, a separate vanadium atom was photographed along with a hydrogen atom.
The diameter of a hydrogen atom is one ten-billionth of a meter. Previously it was believed that it was almost impossible to photograph it with modern equipment. Hydrogen is the most common substance. Its share in the entire Universe is approximately 90%.

According to scientists, other elementary particles can be captured in the same way. “Now we can see all the atoms that make up our world,” said Professor Yuichi Ikuhara. “This is a breakthrough to new forms of production, when in the future it will be possible to make decisions at the level of individual atoms and molecules.”

Hydrogen atom, relative colors
http://prl.aps.org/abstract/PRL/v110/i21/e213001

A group of scientists from Germany, Greece, the Netherlands, the USA and France took pictures of the hydrogen atom. These images, obtained using a photoionization microscope, show an electron density distribution that is completely consistent with the results of theoretical calculations. The work of the international team is presented on the pages of Physical Review Letters.

The essence of the photoionization method is the sequential ionization of hydrogen atoms, that is, the removal of an electron from them due to electromagnetic irradiation. The separated electrons are directed to the sensitive matrix through a positively charged ring, and the position of the electron at the moment of collision with the matrix reflects the position of the electron at the moment of ionization of the atom. The charged ring, which deflects electrons to the side, acts as a lens and with its help the image is magnified millions of times.

This method, described in 2004, had already been used to take “photos” of individual molecules, but physicists went further and used a photoionization microscope to study hydrogen atoms. Since the impact of one electron produces only one point, the researchers accumulated about 20 thousand individual electrons from different atoms and compiled an average image of the electron shells.

According to the laws of quantum mechanics, the electron in an atom does not have any specific position by itself. Only when an atom interacts with the external environment does an electron appear with one probability or another in a certain neighborhood of the atomic nucleus: the region in which the probability of detecting an electron is maximum is called the electron shell. The new images show differences between atoms of different energy states; Scientists were able to clearly demonstrate the shape of electron shells predicted by quantum mechanics.

With the help of other devices, scanning tunneling microscopes, individual atoms can not only be seen, but also moved to the desired location. About a month ago, this technique allowed IBM engineers to draw a cartoon, each frame of which is composed of atoms: such artistic experiments do not have any practical effect, but demonstrate the fundamental possibility of manipulating atoms. For applied purposes, it is no longer atomic assembly that is used, but chemical processes with self-organization of nanostructures or self-limitation of the growth of monatomic layers on the substrate.

A hydrogen atom capturing electron clouds. And although modern physicists, using accelerators, can even determine the shape of a proton, 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. The images that we habitually call photographs and can be found, for example, in any photo report of Lenta.ru, are actually computer models. A light-sensitive matrix in a special device (traditionally it continues to be 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 can we say that scientists managed take a photo atom, is possible only with a fair amount of convention.

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 a beam of electrons, while atomic force microscopes even 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, of course, there is no need to talk about “light painting” here, we will still allow ourselves to call such images photographs.

Experiments by physicists to determine the shape of the 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 gets old

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

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

For example, you can color the cytoskeleton of a nerve cell in red, the synapses in green, and 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 immunohistochemical staining method has revolutionized biological science. And when genetic engineers learned to make transgenic animals with fluorescent proteins, this method experienced a rebirth: for example, mice with neurons painted in different colors became a reality.

In addition, engineers came up with (and practiced) the 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 illumination 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 solved the problem of dyes 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 examining a large specimen through an eyepiece with a narrow field of view, engineers proposed an automatic scanning system: you can put a glass with a sample on the stage of a modern microscope, and the device will independently take a large-scale panorama of the entire sample. At the same time, it will focus in the right places, and then stitch together many frames together.

Some microscopes can contain live mice, rats, or at least small invertebrate animals. Others provide a slight magnification, but are combined with an X-ray machine. To eliminate interference from vibrations, many are mounted on special tables weighing several tons inside rooms 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 searching for the best types of glass and selecting 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 the field of biological research has long been associated with progress in other areas. If there were no computers that could automatically count 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 monitor 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, similar devices were used by gold miners in Kolyma already in the last century.

Beyond the diffraction limit

Optical microscopes have a fundamental disadvantage. The fact is that using the shape of light waves it is impossible to reconstruct the shape of those objects that turned out to be much shorter than the wavelength: with the same success you can try to examine the fine texture of the material with your hand in a thick welding glove.

The limitations created by diffraction have been partially overcome, 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 superposing light waves it is possible to obtain a bright spot with a diameter smaller than wavelength.

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

Electron microscope to 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 specifically with medicine and biology: physicists and chemists who studied significantly smaller objects made do with other means. When they wanted to look at the microworld, diffraction limitations became a serious problem, especially since the fluorescence microscopy methods described above were still unknown. And there is little sense in increasing the resolution from 500 to 100 nanometers if the object that needs to be examined is even smaller!

Knowing that electrons can behave both as a wave and as a particle, physicists from Germany created an electron lens in 1926. The idea behind it was very simple and understandable to any schoolchild: since the electromagnetic field deflects electrons, it can be used to change the shape of a beam of these particles, pulling them apart in different directions, or, conversely, 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 a beam of electrons, and then an electron lens expanded the beam that passed through before it fell on a special luminescent screen. The first microscope provided a magnification of only 400 times, but replacing light with electrons opened the way to photography with a magnification of hundreds of thousands of times: the designers only had to overcome a few technical obstacles.

An electron microscope made it possible to examine the structure of cells in a quality previously unattainable. But from this image 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 illuminate thin sections, but also to examine them in “reflected light” (in reflected electrons, of course). We will not talk in detail about all the variants of microscopes, but we note that recently researchers have learned to reconstruct an image from a diffraction pattern.

Touch, not look

Another revolution occurred through a further departure from the principle of “light and see.” An atomic force microscope, as well as a scanning tunneling microscope, no longer shines anything on the surface of samples. Instead, a particularly thin needle moves across the surface, which literally bounces even on irregularities the size of an individual atom.

Without going into details of all such methods, we note the main thing: the needle of a tunnel 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.

The microscope is called a tunnel microscope because it uses the effect of a tunneling current flowing through a 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.

An atomic force microscope (AFM) is much less demanding on environmental conditions - it can (with a number of restrictions) operate without pumping out air. In a certain sense, AFM is the nanotechnological 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 stylus of a gramophone follows along the grooves of a gramophone record. The bending of the cantilever causes the mirror mounted on it to deflect; 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 beneath the surface of a 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 samples being studied are not always accessible, because minerals or metals usually do not transmit light well. 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 when charged particles accelerated by accelerators are decelerated, makes it possible to study the fossilized remains of prehistoric animals. By rotating the sample under X-rays, we can obtain three-dimensional tomograms - this is how, for example, the brain was found inside the skull of fish that became extinct 300 million years ago. It is possible to do without rotation if the transmitted radiation is recorded by recording the X-rays scattered due to diffraction.

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

Atoms pose

Against the backdrop of all the possibilities that X-ray or optical fluorescence methods provide, a new method 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 stripped from ionized atoms and sent to a special detector. Each act of ionization removes an electron from a certain position and produces one point in the “photograph.” Having accumulated several thousand such points, scientists formed a picture showing the most likely locations for detecting an electron around the nucleus of an atom, and this, by definition, is an electron cloud.

In conclusion, the ability to see individual atoms with their electron clouds is rather the icing on the cake of modern microscopy. It was important for scientists to study the structure of materials, study cells and crystals, and the resulting development of technology 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 rather modest magnification compared to the background of atoms. Neurophysiologists, for example, have long wanted to have a device capable of seeing individual cells inside a living brain, and the creators of Mars rovers would sell their souls for an electron microscope that could fit on board a spacecraft and could work on Mars.

In this photograph you are looking at the first direct image of the orbits of an electron around an atom - in fact, the wave function of the atom!

To photograph the orbital structure of a hydrogen atom, the researchers used a state-of-the-art quantum microscope, an incredible device that allows scientists to peer into the realm of quantum physics.

The orbital structure of space in an atom is occupied by an electron. But to describe these microscopic properties of matter, scientists rely on wave functions—mathematical ways of describing the quantum states of particles—namely, how they behave in space and time.

As a rule, in quantum physics formulas like the Schrödinger equation are used to describe the states of particles.

Obstacles on the path of researchers

Until now, scientists had never actually observed the wave function. Trying to capture the exact position or momentum of a single electron was like trying to catch a swarm of flies. Direct observations were distorted by a very unpleasant phenomenon - quantum coherence.

To measure all quantum states, you need an instrument that can make multiple measurements of a particle's states over time.

But how to increase the already microscopic state of a quantum particle? A group of international researchers found the answer. Using a quantum microscope, a device that uses photoionization to directly observe atomic structures.

In her paper in the popular journal Physical Review Letters, Aneta Stodolna, who works at the Institute of Molecular Physics (AMOLF) in the Netherlands, describes how she and her team obtained the structures of the node electron orbitals of a hydrogen atom placed in a static electric field.

Working method

After irradiation with laser pulses, ionized electrons left their orbits and along a measured trajectory fell into a 2D detector (double microchannel plate. The detector is located perpendicular to the field itself). There are many trajectories along which electrons can travel before colliding with the detector. This provides researchers with a set of interference patterns—models that reflect the nodal structure of the wave function.
The researchers used an electrostatic lens that magnifies the outgoing electron wave by more than 20,000 times.