Scientists have created a new form of matter called the "photonic molecule"! Jan-Teller Metals

An exotic molecule, the existence of which until now was only the subject of theoretical disputes, has finally been obtained by an international team of scientists led by Vera Bendkowsky from the University of Stuttgart (Universität Stuttgart). The opening is the new reinforcement quantum theory describing the behavior of electrons in normal conditions.

The new molecule was "made" of two rubidium atoms, one of which was an ordinary atom and the other a Rydberg atom. This means that one of the electrons in its outer shell was in a highly excited state.

Rydberg atoms themselves are unusual objects. They are obtained when the electron shell is exposed to a laser beam with a certain wavelength. To put it simply, one of the electrons of a Rydberg atom moves away from the nucleus at a distance much, much greater than the electrons in any other atom, but, however, continues to be associated with it.

Chris Greene, a theoretical physicist at the University of Colorado, and a number of his colleagues predicted back in the 1970s that Rydberg and normal atoms could interact to form molecules. But since the electron providing this interaction is extremely distant from its parent atom, the resulting chemical bond- is unusually weak, so that under normal conditions the Rydberg molecule simply cannot exist.

Back in 2000, a group of researchers, including Chris Green, calculated the configuration of the diatomic Rydberg rubidium molecule, calling it a trilobite because of the similarity of the graphical representation of its outer electron shell with an ancient creature. The figure on the left shows this spatial graph, which reflects the probability of finding an outer valence electron at a particular point in space, and on the right you can see the trilobite itself (illustration by Greene, Dickinson, Sadeghpour, photo from colorado.edu).

It took many years to perfect the technique of cooling atoms to a temperature close to absolute zero to finally be able to create such an exotic molecule.

This is exactly what Bendkowski and her colleagues did. Vera explains: “The nuclei of atoms must be at the right distance from each other so that the electronic fields “find” each other and begin to interact. We used an ultracold cloud of rubidium, in which, as the temperature decreased, the atoms of the gas came closer and closer. ”

Using a laser, the scientists converted some of these atoms into a Rydberg state. At a temperature very close to zero, this "critical distance" was about 100 nanometers.

This distance between two atoms forming a molecule is approximately 1000 times greater than usual (tens and hundreds of picometers). It is not surprising that even with absolute zero Rydberg molecules are very unstable. The longest-lived one obtained in the experiment lasted 18 microseconds.

Back in 1934, the great Fermi predicted that if one atom meets a "wandering" electron, it will be able to interact with it. But Fermi didn't go so far as to form a molecule with this kind of superweak bond, Green explains.

Experience details can be found in

Rydberg states- states of atoms, ions and molecules with large values of the principal n(highly excited states). Named in honor of J. R. Rydberg, who first experimentally studied atomic spectra near the border.

R. s. atoms and ions are characterized by extremely small (atomic scale) ionization. potentials, long lifetimes (since the probability of radiative quantum transitions from them is small), and large radii of the orbits of a highly excited (Rydberg) electron. R. s. are similar to the states of the hydrogen atom. Transitions between neighboring R. s. are in the radio range. Great importance P allows to apply to R.'s description of page. semiclassical approximation and use the concepts of classical for them. mechanics. The large dimensions of the orbits and the low binding energies of the Rydbert electron determine the high sensitivity of R. s. to the effects of electricity. and magn. fields and large eff. cross section of the interaction of atoms in R. s. with charged particles.

In table. 1 shows the values of the main. characteristics of atoms and atomic ions located in R. s.

Tab. 1.

Systematic R.'s studying with. became possible from the beginning. 1970s thanks to success laser spectroscopy, which allowed to explore in the lab. R.'s conditions with. with ha ~ 300, as well as radio astronomy, since absorption lines were found in interstellar clouds between the R. with. from ha 700.

Wave functions and energies of Rydberg states of atoms. wave functions R. s. with good accuracy can be represented as a product of the wave functions of the Rydberg electron and the remaining atomic system - the atomic remnant. Properties of an atom in R. s. are mainly determined by the wave function of a highly excited electron, which is eigenvalue. function:

where is the momentum operator, U(r) is the potential energy of the interaction of the Rydberg electron with the atomic core. At distances r electron from atomic nucleus, many large sizes of the atomic residue, U(r) transforms into the Coulomb potential: U(r) = Ze 2 /r.

Energy R. s. insulated atoms, counted from the ionization boundary, are determined by the Rydberg formula:

Where M- mass of the atomic residue, - quantum defect, weakly dependent on n and for the orbital quantum number l> 2 very rapidly decreasing with growth l. Values for S-, P- And D-states of atoms alkali metals are given in table. 2.

Tab. 2.

Probabilities will radiate. quantum transitions of an atom on R. s. fall rapidly with growth P And l. For insulated atom in R. s. with data ha and l lifetime . If the distribution of atoms over l thermodynamic equilibrium [~(2l + 1)], then the probability of being emitted. transitions between R. with. With n And n" determined by the Kramers formula (with an error of less than 20%):

where are the level energies counted from the ionization boundary. Wed the probability of a transition from a given level to all other energy levels is the reciprocal of cf. lifetime of the system at this level.

Rydberg states in an electric field fundamentally non-stationary - an atom is ionized by a field. However, for weak fields, the autoionization probability ( field ionization) is exponentially small and R. s. can be considered quasi-stationary. In the electric field, highly excited energy levels experience Stark splitting and shift (see Fig. Stark effect), their wave functions are proper. functions of the Hamiltonian:

Where H0 is the Hamiltonian (1) of the atom in the absence of a field. If the potential energy U(r) has a Coulomb nature (i.e., H 0 is the Hamiltonian of a hydrogen-like ion), then the Schrödinger equation corresponding to the Hamiltonian (4) is divided into parabolic. coordinates. The projection of the magnetic moment per field direction is still an integral of motion. Up to the second order of perturbation theory, the energy of stationary states measured from the ionization boundary is given by

(n 1, n 2- parabolic. quantum numbers satisfying the condition: n 1 + n 2 + 1 = n - t, t- magn. quantum number). The fe-ro expression for the order of perturbation theory is given in . Formula (5) is also valid for R. s. in non-hydrogen-like atoms, if the scale of the Stark splitting determined by the second term exceeds the energy difference between states with different . On fig. 1 as an example shows the level diagram of Li in electric. field.

Rice. Fig. 1. Scheme of energy levels of the Li atom in an electric field for n ~ 15 (|m| = 1).

Probability of electric ionization. field of hydrogen-like atoms in R. s. is defined asymptotically. f-loy:

The probability of ionization of an atom in R. s. increases sharply when the intensity of the electric. fields E approaches the value , at which autoionization is possible within the framework of the classical. mechanics.

Rydberg states in a magnetic field. In contrast to the usual weakly excited states, for which the main role played by the paramagnet. interaction of an atom with a magnet. field (see Zeemapa effect, Pashen - Baka effect), for atoms in R. s. important role diamagnet plays. an interaction that grows very rapidly with increasing p. R. s. in magn. the field is described by the Hamiltonian:

Where L and S are the total momentum and spin of the atom, respectively, IN- magn. induction, is the Bohr magneton, is the angle between the radius vector of the Rydberg electron and the magnetic field vector. fields. The second term describes the paramagnetic, the third - diamagnetic interactions. For R. s. diamag. interaction grows for high P becomes decisive. In weak fields the role is played by the second term, which gives a splitting into m-components with a characteristic value that is qualitatively the same as for weakly excited states. As the field strength increases, the contribution of the diamagnet increases. interactions that link states with the same m l And . [For state 4p ( t = 1) in a hydrogen atom diamagn. and paramagn. interactions are aligned at B = 2*10 7 Gs.] Each level with quantum numbers P And T split into a component. With a further increase in the field strength, levels with different P and the spectrum of hydrogen in magn. field (Fig. 2) becomes similar to the spectrum of an atom in electric. field. In the case of extremely strong fields, the main role played by the interaction with the magnet. field and R. s. are Landau states (see Landau levels), the Coulomb interaction can then be regarded as a perturbation.

Rice. 2. Scheme of energy levels of the H atom in Rydberg states in a magnetic field (m = 1, even states).

Interaction of Atoms in the Rydberg State with Charged Particles. Eff. sections s of quantum transitions in atoms located in the R. s. in collisions with charged particles (electrons, ions), they grow like geom. section ~n 4 . For transitions with small main the role is played by the long-range dipole interaction, which leads to , and at high energies ext. particle energy dependence is given by a factor (quantum logarithm!). With growth, the short-range interaction begins to play an increasingly important role, which makes it possible to neglect the field of the atomic residue in the collision process, and consider the collision itself in the framework of the classical. mechanics. This approach, called the classical binary approximation, allows you to get ; at high energies. In the Born approximation, the transition cross section in a collision with electrons is determined by f-loy (3):

Function for n = 100 is given in table. 3.

T a b l. 3.

Transitions between R. with. in collisions with electrons are DOS. cause additional (in addition to the Doppler) inelastic broadening recombination radio links observed from a number of astrophysic. objects (planetary nebulae, interstellar medium, NI zones, etc.).

In collision. transitions between R. with. with the same P main ions usually play a role. Naib. the cross sections for transitions between neighboring levels due to the dipole interaction are large. They are an order of magnitude or more superior to the geom. section

Interaction of atoms in the Rydberg state with neutral atoms. If P is sufficiently large, then the cross section of the process of interaction of atoms in R. s. with neutral atoms is expressed in terms of the scattering amplitude of a free electron on a neutral atom and the scattering amplitude of an atom on a positively charged atomic core. Eg, as a result of interaction with neutral atoms R. of page. experience a broadening and a shift proportional to the concentration of perturbing particles N:

coefficient are expressed in terms of the amplitude of elastic scattering of an electron on an atom and the parameters of the interaction of a neutral atom with an atomic core, and for sufficiently large P strive for constants; in the intermediate region, their behavior can be very complex and depends on the particular type of perturbing particles. For Cs atoms in R. s. perturbed, for example, by Ar atoms, asymptotically. values ,; if the perturbing atoms are Cs atoms, then it increases by a factor of 20, and by 2 orders of magnitude. Asimitotic coefficient values. and reach when interacting with atoms of inert gases at , and when interacting with atoms of alkali metals at . The behavior of the cross sections of other processes of interaction of atoms in R. s. with neutral atoms (mixing of states with respect to l, disorientation, etc.) is qualitatively analogous to the behavior of the broadening cross sections.

Laboratory experiments. R. s. in the lab conditions are created most often by the excitation of an atom from the main. state of one or several. light beams of high intensity (at least at the first stage of excitation - pumping). For pumping, an N 2 laser or the second (third) harmonic of a neodymium glass laser is usually used. To receive R. with. with given quantum numbers n, l, t, at the second stage, the atomic system is excited by the radiation of powerful tunable dye lasers.

For R.'s registration with. max. the fluorescent method and the electric ionization method were widely used. field. The fluorescent method is based on the analysis of the cascade emission of light during the transitions of an atom from R. s. This method is selective, but the intensity of the detected radiation in the visible region is low in this case. The fluorescent method is used, as a rule, for R.'s research by page. With P< 20.

In the method of ionization electric. the field registers electrons released as a result of ionization of the atom in R. s. when exposed to electricity. fields. In this case, selectivity is ensured by an extremely sharp dependence of the ionization probability on quantum numbers P And T. Most often, this method is used in a time-resolved mode: after pulsed excitation of R. s. a sawtooth electrical impulse is applied. fields. Each R. s. in time-allowed ionization. signal gives a peak after a strictly defined time from the moment the field is turned on. The method differs in simplicity, high sensitivity and unlike a fluorescent method is especially effective at R.'s research of page. with big P when high voltages are not required for ionization. fields.

Spectra of atoms and ions in R. s. diff. methods. With the help of conventional multimode lasers, a spectral resolution of the order of the Doppler level width is achieved, which makes it possible to study radioactivity. With . If more is required a high resolution, then the method of crossed atomic laser beams is used, which gives a resolution of several MHz, or the methods of nonlinear laser spectroscopy. For example, a spectrum with a resolution of the order of KHz was obtained by the method of two-photon spectroscopy. In cases where the intervals between adjacent R. s are of interest, the methods are more convenient. radiospectroscopy,, quantum beats, and level crossings (see State Interference). Instead of setting the radiation frequency to the transition frequency between R. s., to a given external. the frequency field can be adjusted by R. s. In this case, R. s. allow amplification of a weak microwave signal. This method obtained sensitivity in the millimeter range; there is reason to expect an increase in sensitivity by another 2 orders of magnitude.

Of particular interest are experiments with atoms in R. s. in the resonators. For n~ 30 transitions between R.. s. lie in the millimeter range, for which there are resonators with a very high . At the same time, the effect of electric fields on atoms in R. s. more significantly than, for example, for molecular rotation. energy levels, therefore, with the help of R. s. For the first time, it was possible to demonstrate a number of quantum effects predicted in the 1950s and 1960s: the suppression of spontaneous radiation. transcoding in the resonator, Rabi nutation - interaction with fields of one photon in , cooperative Dicke effects for several. atoms (see superradiance)and etc. .

Astrophysical applications of Rydberg states. The first observations will radiate, transitions between R. s. from astrophysicists. objects (lines and) were made in the USSR. Radio emission lines corresponding to transitions between radio waves are observed up to n~ 300 from galactic H II zones, planetary nebulae, the central regions of our Galaxy, and some other galaxies. Lines He, He II, C II were also found. Main R.'s mechanism of formation of page. in astrophys. objects is photorecombination, so the radio emission lines are called. also recombination. radio links. Radio links between R. s. play an important role in the diagnosis of astrophys. objects. For P < 100 ширина таких линий обусловлена и позволяет судить о ионной темп-ре космич. плазмы. Для более высоких P collisions with electrons contribute to the broadening, and so on. electrons can also be estimated from the width of the radio lines. The ratio of the intensities of the radio lines and the continuum gives the electronic temperature.

In interstellar clouds, absorption radio lines have been found that belong to the C II ion and correspond to transitions between radio waves. With P > 700.

Lit.: 1) R y d b e r g J. R., “Z. Phys. Chem., 1890, Bd 5, S. 227; 2) Rydberg states of atoms and molecules, trans. from English, M., 1985; 3) Vainshtein L. A., Sobelman I. I., Yuk o v E. A., Excitation of atoms and , M., 1979; 4) Nagoe he S., Raimond J. M., "Adv. in Atom. and Molec. Phys.", 1985, v. 20, p. 347; 5) Sorochenko R. L., Recombination of radio lines, in the book: Space Physics, 2nd ed., M., 1986. I. L. Beigman,

Rydberg states of molecules. The highly excited electronic states of matter, like the atomic states, are similar to a series of states of the hydrogen atom. The Rydberg orbitals of molecules are denoted by the principal P and orbital l quantum numbers and group type symmetry of the molecule(e.g. nsa 1 , npb 1). R.'s energy with. (measured from the molecular ionization boundary) is determined by the Rydberg f-loop (2). For a molecule consisting of atoms of the first period, the magnitude of the quantum defect for nd-orbitals is very small (0.1), for np-orbitals are slightly higher (0.3-0.5), and for ns-orbitals are much more (0.9-1.2). R.'s stability with. molecules depends on the stability of the main. state or low-lying excited state of a molecular ion resulting from the removal of a Rydberg electron, since the Rydberg orbital, generally speaking, is nonbonding. The stability of an ion depends on whether an electron is removed from a bonding, loosening, or nonbonding molecular orbital, basic. state of a neutral molecule. For example, for H 2 O from employed molecular orbitals in the axis. the topmost state is the nonbonding molecular orbital 1 b 1. Therefore, the main the state of the H 2 O + ion, resulting from the removal of an electron from this orbital, is as stable as the main. the state of the H 2 O molecule: practically all R. s. H 2 O molecules converging to the main. state of the H 2 O + ion, are stable.

If an electron moves from a low-lying to a higher molecular orbital with the same P, then the resulting states are called subrydbergovsky and. T. to. P is not a well-defined quantum number for low molecular orbitals, sub-Rydberg states differ little from R. s. molecules, although sub-Rydberg orbitals can also be bonding.

R. s. molecules differ from R. with. atoms Ch. arr. due to vibrations, rotations and the possibility of dissociation of the ionic core of the molecule. If the ion core is in an excited vibration. state, then the Rydberg electron, when penetrating into the ionic core (which happens quite rarely, with a probability), can experience an inelastic collision with the core, acquire sufficient kinetic energy. energy from vibrations. core energy and lead to ionization of the molecule, called. vibrational autoionization. The process of autoionization is also possible due to rotation. Highly excited R. s. molecules usually lie so close that the energetic. the interval between them is of the same order or even less than the vibrating quantum. or rotate. the energy of the molecule. Therefore, the separation of electronic and nuclear motions, adopted in the Bern-Oppenheimer approximation, is often used for molecules in R. s. becomes unusable.

Lit.: Herzberg G., Electronic spectra and structure of polyatomic molecules, trans. from English, M., 1969; Rydberg states of atoms and molecules, ed. R. Stebbings, F. Dunving, trans. from English, M., 1985. M. R. Aliyev.

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Rydberg atoms(named after J. R. Rydberg) - hydrogen-like atoms and alkali metal atoms, in which the outer electron is in a highly excited state (up to levels n about 1000). To transfer an atom from its ground state to an excited state, it is irradiated with resonant laser light or an RF discharge is initiated. The size of a Rydberg atom can exceed the size of the same atom in the ground state by almost 106 times for n = 1000 (see table below).

An electron revolving in an orbit of radius r around the nucleus, according to Newton's second law, it experiences a force

From these two equations, we obtain an expression for the orbital radius of an electron in the state n :

Where Ry = 13.6 eV is the Rydberg constant, and δ is the nuclear charge defect, which at large n insignificant. Energy difference between n-m and ( n+1)-th energy levels is equal to

Characteristic size of an atom rn and typical semiclassical period of electron revolution are equal to

The wavelength of the emission of a hydrogen atom during the transition from n′ = 91 on n = 90 equal to 3.4 cm.

When atoms are excited from the ground state to the Rydberg state, interesting phenomenon called "dipole blockade".

Coherent control of the dipole blockade of Rydberg atoms by laser light makes them a promising candidate for the practical implementation of a quantum computer. According to the scientific press, until 2009, the two-qubit gate element, which is important for computing, was not experimentally implemented. However, there are reports on the observation of collective excitation and dynamic interaction between two atoms and in mesoscopic samples.

Strongly interacting Rydberg atoms are characterized by quantum critical behavior, which provides a fundamental scientific interest to them regardless of the application.

Studies related to the Rydberg states of atoms can be conditionally divided into two groups: the study of the atoms themselves and the use of their properties for other purposes.

In 2009, researchers from managed to obtain the Rydberg molecule (English) .

The first experimental data on Rydberg atoms in radio astronomy were obtained in 1964 by R. S. Sorochenko et al. (FIAN) on a 22-meter mirror radio telescope designed to study the radiation of space objects in the centimeter frequency range. When focusing the telescope on the Omega Nebula, in the spectrum of radio emission coming from this nebula, an emission line was detected at a wavelength of λ ≃ 3.4 cm. This wavelength corresponds to the transition between Rydberg states n′ = 91 And n = 90 in the spectrum of the hydrogen atom

Plan:

1 Properties of Rydberg atoms
- 1.1 Dipole blockade of Rydberg atoms
2 Directions of research and possible applications

Introduction

Rydberg atoms(named after J. R. Rydberg) - alkali metal atoms, in which the outer electron is in a highly excited state (up to levels n ~ 100). To transfer an atom from its ground state to an excited state, it is irradiated with resonant laser light or an RF discharge is initiated. The size of the Rydberg atom is much larger than the size of the same atom in the ground state by almost 10,000 times for n=100 (see table below).

1. Properties of Rydberg atoms

An electron revolving in an orbit of radius r around the nucleus, according to Newton's second law, it experiences a force:

Where k= 1/(4πε 0), e is the charge of an electron.

Orbital moment in units ħ equals:

From these two equations, we obtain an expression for the orbital radius of an electron in the state "n"

Scheme of laser excitation of a rubidium atom into the Rydberg state

The binding energy of such a hydrogen-like atom is

where Ry = 13.6 eV is the Rydberg constant, and δ nuclear charge defect, which at large n insignificant. Energy difference between n-m and n+1-th energy levels is approximately equal to

Characteristic size of an atom rn and typical semiclassical period of electron revolution are equal to

Where a B = 0.5×10 −10 m is the Bohr radius, and T 1 ~ 10 −16 s.

Let us compare some numbers of the ground and Rydberg states of the hydrogen atom.

1.1. Dipole blockade of Rydberg atoms

When atoms are excited from the ground state to the Rydberg state, an interesting phenomenon occurs, called dipole blockade. In a discharged atomic vapor, the distance between atoms in the ground state is large and there is practically no interaction between atoms. However, when atoms are excited to the Rydberg state, their orbital radius increases by n 2 up to ~1 µm. As a result, the atoms "approach", the interaction between them increases significantly, which causes a shift in the energy of the states of the atoms. What does this lead to? Let us assume that only one atom can be excited from the ground state to the Rieberg state by a weak light pulse. An attempt to populate the same level with another atom becomes obviously impossible due to the "dipole blockade".

2. Directions of research and possible applications

Studies related to the Rydberg states of atoms can be conditionally divided into two groups: the study of the atoms themselves and the use of their properties for other purposes.

Fundamental areas of research:

Of several states with large n it is possible to compose a wave packet, which will be more or less localized in space. If the orbital quantum number is also large, then we will get an almost classical picture: a localized electron cloud rotates around the nucleus at a great distance from it.
If the orbital momentum is small, then the motion of such a wave packet will be quasi-one-dimensional: The electron cloud will move away from the nucleus and approach it again. This is an analogue of a highly elongated elliptical orbit in classical mechanics while moving around the sun.
Behavior of the Rydberg electron in external electric and magnetic fields. Ordinary electrons close to the nucleus mostly feel the strong electrostatic field of the nucleus (on the order of 10 9 V/cm), and the external fields for them play the role of only small additions. The Rydberg electron feels a strongly weakened field of the nucleus ( E~E0/n4), and therefore external fields can radically distort the motion of an electron.
Atoms with two Rydberg electrons have interesting properties, with one electron "spinning" around the nucleus at a greater distance than the other. Such atoms are called planetary.
According to one of the hypotheses, ball lightning consists of the Rydberg substance.

The unusual properties of Rydberg atoms are already finding applications

Quantum detectors of radio emission: Rydberg atoms can register even a single photon in the radio range, which is far beyond the capabilities of conventional antennas.
The stepped energy spectrum of a Rydberg electron serves as an "energy balance" that can be used for accurate energy measurements.
Rydberg atoms are also observed in the interstellar medium. They are very sensitive pressure sensors, created for us by nature itself.

In 2009, researchers from the University of Stuttgart succeeded in obtaining the Rydberg molecule.

Notes

W. Demtroder Laser Spectroscopy: Basic Concepts & Instrumentation. - Springer, 2009. - 924 p. - ISBN 354057171X
R. Heidemann et al. (2007). "Evidence for Coherent Collective Rydberg Excitation in the Strong Blockade Regime - link.aps.org/abstract/PRL/v99/e163601". Physical Review Letters 99 (16): 163601. DOI:10.1103/PhysRevLett.99.163601 - dx.doi.org/10.1103/PhysRevLett.99.163601. arΧiv:quant-ph/0701120 - arxiv.org/abs/quant-ph/0701120.
Cohesion in ball lightning - scitation.aip.org/journals/doc/APPLAB-ft/vol_83/iss_11/2283_1.html
membrana.ru "For the first time in the world, the Rydberg molecule has been obtained" - www.membrana.ru/lenta/?9250

Alkali metals, in which the outer electron is in a highly excited state (up to levels n about 1000). To transfer an atom from its ground state to an excited state, it is irradiated with resonant laser light or an RF discharge is initiated. The size of a Rydberg atom can exceed the size of the same atom in the ground state by almost 106 times for n = 1000 (see table below).

Properties of Rydberg atoms

An electron revolving in an orbit of radius r around the nucleus, according to Newton's second law, it experiences a force

where ( - dielectric susceptibility), e is the charge of an electron.

Orbital moment in units ħ equals

From these two equations, we obtain an expression for the orbital radius of an electron in the state n :

Scheme of laser excitation of a rubidium atom into a Rydberg state.

The binding energy of such a hydrogen-like atom is

Where Ry= 13.6 eV is the Rydberg constant, and δ - nuclear charge defect, which at large n insignificant. Energy difference between n-th and n+1-th energy levels is approximately equal to

Characteristic size of an atom rn and typical semiclassical period of electron revolution are equal to

Where a B= 0.5 10 −10 m is the Bohr radius, and T 1 ~ 10 −16 s.

Parameters of the first excited and Rydberg states of the hydrogen atom

Principal quantum number,	First excited state,	Rydbergovskoe state,
Binding energy of an electron in an atom (ionization potential), eV	≃ 5	≃ 10 −5
Atom size (electron orbit radius), m	~ 10 −10	~ 10 −4
Electron orbital period, s	~ 10 −16	~ 10 −7
Natural lifetime, s	~ 10 −8	~ 1

The wavelength of the emission of a hydrogen atom during the transition from n′ = 91 on n = 90 equal to 3.4 cm

Dipole blockade of Rydberg atoms

When atoms are excited from the ground state to the Rydberg state, an interesting phenomenon occurs, called "dipole blockade".

In a rarefied atomic vapor, the distance between atoms in the ground state is large, and there is practically no interaction between atoms. However, upon excitation of atoms to the Rydberg state, their orbital radius increases in and reaches a value of the order of 1 μm. As a result, the atoms "approach", the interaction between them increases significantly, which causes a shift in the energy of the states of the atoms. What does this lead to? Let us assume that only one atom can be excited from the ground state to the Rieberg state by a weak light pulse. An attempt to populate the same level with another atom becomes obviously impossible due to the "dipole blockade".

Directions of research and possible applications

Studies related to the Rydberg states of atoms can be conditionally divided into two groups: the study of the atoms themselves and the use of their properties for other purposes.

Fundamental areas of research:

The unusual properties of Rydberg atoms are already finding applications

In 2009, researchers from managed to obtain the Rydberg molecule (English) Russian .

radio astronomy

Notes

Literature

Neukamner J., Rinenberg H., Vietzke K. et al. Spectroscopy of Rydberg Atoms at n ≅ 500 // Phys. Rev. Lett. 1987 Vol. 59. P. 26.
Frey M. T. Hill S.B.. Smith K.A.. Dunning F.B., Fabrikant I.I. Studies of Electron-Molecule Scattering at Microelectronvolt Energies Using Very-High-n Rydberg Atoms // Phys. Rev. Lett. 1995 Vol. 75, No. 5. P. 810-813.
Sorochenko R. L., Salomonovich A. E. Giant atoms in space // Nature. 1987. No. 11. S. 82.
Dalgarno A. Rydberg atoms in astrophysics // Rydberg states of atoms and molecules: Per. from English. / Ed. R. Stebbins, F. Dunning. M.: Mir. 1985, p. 9.
Smirnov BM Excited atoms. Moscow: Energoizdat, 1982. Ch. 6.

Plan:

Introduction

1. Properties of Rydberg atoms

1.1. Dipole blockade of Rydberg atoms

2. Directions of research and possible applications

Notes

Properties of Rydberg atoms

Dipole blockade of Rydberg atoms

Directions of research and possible applications

radio astronomy

Notes

Literature

Links

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