Rydberg matter[1] is an exotic phase of matter formed by Rydberg atoms; it was predicted around 1980 by É. A. Manykin, M. I. Ozhovan and P. P. Poluéktov.[2][3] It has been formed from various elements like caesium,[4] potassium,[5] hydrogen[6][7] and nitrogen;[8] studies have been conducted on theoretical possibilities like sodium, beryllium, magnesium and calcium.[9] It has been suggested to be a material that diffuse interstellar bands may arise from.[10] Circular[11] Rydberg states, where the outermost electron is found in a planar circular orbit, are the most long-lived, with lifetimes of up to several hours,[12] and are the most common.[13][14][15]
Physical
A 19-atom planar Rydberg matter cluster. At the seventh excitation level, spectroscopy on K19 clusters showed the bond distance to be 5.525 nm.[16]
Schematic of valence electron distribution in a Rydberg matter made of excited (n=10) Cs atoms.
Rydberg matter consists of usually[17] hexagonal[18][16] planar[19] clusters; these cannot be very big because of the retardation effect caused by the finite velocity of the speed of light.[19] Hence, they are not gases or plasmas; nor are they solids or liquids; they are most similar to dusty plasmas with small clusters in a gas. Though Rydberg matter can be studied in the laboratory by laser probing,[20] the largest cluster reported consists of only 91 atoms,[7] but it has been shown to be behind extended clouds in space[10][21] and the upper atmosphere of planets.[22] Bonding in Rydberg matter is caused by delocalisation of the high-energy electrons to form an overall lower energy state.[3] The way in which the electrons delocalise is to form standing waves on loops surrounding nuclei, creating quantised angular momentum and the defining characteristics of Rydberg matter. It is a generalised metal by way of the quantum numbers influencing loop size but restricted by the bonding requirement for strong electron correlation;[19] it shows exchange-correlation properties similar to covalent bonding.[23] Electronic excitation and vibrational motion of these bonds can be studied by Raman spectroscopy.[24]
Lifetime
Schematic of an effective potential within a Wigner-Seitz cell of a Rydberg matter made of excited (n=10) Cs atoms.[25][26]
Due to reasons still debated by the physics community because of the lack of methods to observe clusters,[27] Rydberg matter is highly stable against disintegration by emission of radiation; the characteristic lifetime of a cluster at n = 12 is 25 seconds.[26][28] Reasons given include the lack of overlap between excited and ground states, the forbidding of transitions between them and exchange-correlation effects hindering emission through necessitating tunnelling[23] that causes a long delay in excitation decay.[25] Excitation plays a role in determining lifetimes, with a higher excitation giving a longer lifetime;[26] n = 80 gives a lifetime comparable to the age of the Universe.[29]
Excitations
| n | d (nm) | D (cm−3) |
|---|---|---|
| 1 | 0.153 | 2.8×1023 |
| 4 | 2.45 | |
| 5 | 3.84 | |
| 6 | 5.52 | |
| 10 | 15.3 | 2.8×1017 |
| 40 | 245 | |
| 80 | 983 | |
| 100 | 1534 | 2.8×1011 |
In ordinary metals, interatomic distances are nearly constant through a wide range of temperatures and pressures; this is not the case with Rydberg matter, whose distances and thus properties vary greatly with excitations. A key variable in determining these properties is the principal quantum number n that can be any integer greater than 1; the highest values reported for it are around 100.[29][30] Bond distance d in Rydberg matter is given by
\( d=2.9n^{{2}}a_{{0}}\, \)
where a0 is the Bohr radius. The approximate factor 2.9 was first experimentally determined, then measured with rotational spectroscopy in different clusters.[16] Examples of d calculated this way, along with selected values of the density D, are given in the adjacent table.
Condensation
Like bosons that can be condensed to form Bose–Einstein condensates, Rydberg matter can be condensed, but not in the same way as bosons. The reason for this is that Rydberg matter behaves similarly to a gas, meaning that it cannot be condensed without removing the condensation energy; ionisation occurs if this is not done. All solutions to this problem so far involve using an adjacent surface in some way, the best being evaporating the atoms of which the Rydberg matter is to be formed from and leaving the condensation energy on the surface.[31] Using caesium atoms, graphite-covered surfaces and thermionic converters as containment, the work function of the surface has been measured to be 0.5 eV,[32] indicating that the cluster is between the ninth and fourteenth excitation levels.[25]
See also
State of matter
The Journal of Cluster Science has dedicated in 2012 a special issue (Volume 23, Issue 1) to “Rydberg-Matter and Excited-State Clusters”.[33]
The President of Russian Academy of Sciences Vladimir Fortov has recently noted the works on Rydberg Matter as a great scientific event.[34]
References
Wang, Jiaxi; Holmlid, Leif (2002). "Rydberg Matter clusters of hydrogen with well-defined kinetic energy release observed by neutral time-of-flight". Chemical Physics. 277 (2): 201. Bibcode:2002CP....277..201W. doi:10.1016/S0301-0104(02)00303-8.
É.A. Manykin; M.I. Ozhovan; P.P. Poluéktov (1980). "Transition of an excited gas to a metallic state". Sov. Phys. Tech. Phys. Lett. 6: 95.
É.A. Manykin, M.I. Ozhovan, P.P. Poluéktov; Ozhovan; Poluéktov (1981). "On the collective electronic state in a system of strongly excited atoms". Sov. Phys. Dokl. 26: 974–975. Bibcode:1981SPhD...26..974M.
V.I. Yarygin; V.N. Sidel’nikov; I.I. Kasikov; V.S. Mironov & S.M. Tulin (2003). "Experimental Study on the Possibility of Formation of a Condensate of Excited States in a Substance (Rydberg Matter)". JETP Letters. 77 (6): 280. Bibcode:2003JETPL..77..280Y. doi:10.1134/1.1577757.
S. Badiei & L. Holmlid (2002). "Neutral Rydberg Matter clusters from K: Extreme cooling of translational degrees of freedom observed by neutral time-of-flight". Chemical Physics. 282 (1): 137–146. Bibcode:2002CP....282..137B. doi:10.1016/S0301-0104(02)00601-8.
S. Badiei & L. Holmlid (2006). "Experimental studies of fast fragments of H Rydberg matter". Journal of Physics B. 39 (20): 4191–4212. Bibcode:2006JPhB...39.4191B. doi:10.1088/0953-4075/39/20/017.
J. Wang; Holmlid, Leif (2002). "Rydberg Matter clusters of hydrogen (H2)N* with well-defined kinetic energy release observed by neutral time-of-flight". Chemical Physics. 277 (2): 201. Bibcode:2002CP....277..201W. doi:10.1016/S0301-0104(02)00303-8.
S. Badiei & L. Holmlid (2002). "Rydberg Matter of K and N2: Angular dependence of the time-of-flight for neutral and ionized clusters formed in Coulomb explosions". International Journal of Mass Spectrometry. 220 (2): 127. Bibcode:2002IJMSp.220..127B. doi:10.1016/S1387-3806(02)00689-9.
A.V. Popov (2006). "Search for Rydberg matter: Beryllium, magnesium and calcium". Czechoslovak Journal of Physics. 56 (S2): B1294–B1299. Bibcode:2006CzJPh..56B1294P. doi:10.1007/s10582-006-0365-2.
L. Holmlid (2008). "The diffuse interstellar band carriers in interstellar space: All intense bands calculated from He doubly excited states embedded in Rydberg Matter". Monthly Notices of the Royal Astronomical Society. 384 (2): 764–774. Bibcode:2008MNRAS.384..764H. doi:10.1111/j.1365-2966.2007.12753.x.
J. Liang; M. Gross; P. Goy; S. Haroche (1986). "Circular Rydberg-state spectroscopy". Physical Review A. 33 (6): 4437–4439. Bibcode:1986PhRvA..33.4437L. doi:10.1103/PhysRevA.33.4437. PMID 9897204.
R.L. Sorochenko (1990). "Postulation, detection and observations of radio recombination lines". In M.A. Gordon; R.L. Sorochenko (eds.). Radio recombination lines: 25 years of investigation. Kluwer. p. 1. ISBN 978-0-7923-0804-1.
L. Holmlid (2007). "Direct observation of circular Rydberg electrons in a Rydberg Matter surface layer by electronic circular dichroism". Journal of Physics: Condensed Matter. 19 (27): 276206. Bibcode:2007JPCM...19A6206H. doi:10.1088/0953-8984/19/27/276206.
L. Holmlid (2007). "Stimulated emission spectroscopy of Rydberg Matter: observation of Rydberg orbits in the core ions". Applied Physics B. 87 (2): 273–281. Bibcode:2007ApPhB..87..273H. doi:10.1007/s00340-007-2579-9.
L. Holmlid (2009). "Nuclear spin transitions in the kHz range in Rydberg Matter clusters give precise values of the internal magnetic field from orbiting Rydberg electrons". Chemical Physics. 358 (1): 61–67. Bibcode:2009CP....358...61H. doi:10.1016/j.chemphys.2008.12.019.
Holmlid, Leif (2008). "Rotational spectra of large Rydberg Matter clusters K37, K61 and K91 give trends in K-K bond distances relative to electron orbit radius". Journal of Molecular Structure. Elsevier BV. 885 (1–3): 122–130. doi:10.1016/j.molstruc.2007.10.017. ISSN 0022-2860.
Holmlid, Leif (2008). "Clusters HN+ (N=4, 6, 12) from condensed atomic hydrogen and deuterium indicating close-packed structures in the desorbed phase at an active catalyst surface". Surface Science. Elsevier BV. 602 (21): 3381–3387. doi:10.1016/j.susc.2008.09.007. ISSN 0039-6028.
Holmlid, L. (2007-04-20). "Precision bond lengths for Rydberg Matter clusters K19 in excitation levelsn=4, 5 and 6 from rotational radio-frequency emission spectra". Molecular Physics. Informa UK Limited. 105 (8): 933–939. arXiv:physics/0607193. doi:10.1080/00268970701197387. ISSN 0026-8976.
Holmlid, Leif (1998). "Classical energy calculations with electron correlation of condensed excited states — Rydberg Matter". Chemical Physics. Elsevier BV. 237 (1–2): 11–19. doi:10.1016/s0301-0104(98)00259-6. ISSN 0301-0104.
Åkesson, Haideh; Badiei, Shahriar; Holmlid, Leif (2006). "Angular variation of time-of-flight of neutral clusters released from Rydberg Matter: Primary and secondary Coulomb explosion processes". Chemical Physics. Elsevier BV. 321 (1–2): 215–222. doi:10.1016/j.chemphys.2005.08.016. ISSN 0301-0104.
Holmlid, Leif (2006-10-26). "Amplification by Stimulated Emission in Rydberg Matter Clusters as the Source of Intense Maser Lines in Interstellar Space". Astrophysics and Space Science. Springer Science and Business Media LLC. 305 (1): 91–98. doi:10.1007/s10509-006-9067-2. ISSN 0004-640X.
Holmlid, Leif (2006). "The alkali metal atmospheres on the Moon and Mercury: Explaining the stable exospheres by heavy Rydberg Matter clusters". Planetary and Space Science. Elsevier BV. 54 (1): 101–112. doi:10.1016/j.pss.2005.10.005. ISSN 0032-0633.
Manykin, E.A.; Ojovan, M.I.; Poluektov, P.P. (1983). "Theory of the condensed state in a system of excited atoms" (PDF). Journal of Experimental and Theoretical Physics. 57 (2): 256–262.
Holmlid, Leif (2008). "Vibrational transitions in Rydberg matter clusters from stimulated Raman and Rabi-flopping phase delay in the infrared". Journal of Raman Spectroscopy. Wiley. 39 (10): 1364–1374. doi:10.1002/jrs.2006. ISSN 0377-0486.
Manykin, É. A.; Ozhovan, M. I.; Poluéktov, P. P. (1992). "[Decay of a condensate consisting of excited cesium atoms]". Журнал Экспериментальной и Теоретической Физики. 102: 1109. translation: Manykin, É. A.; Ozhovan, M. I.; Poluéktov, P. P. (1992). "Decay of a condensate consisting of excited cesium atoms". Journal of Experimental and Theoretical Physics. 75 (4): 602.
Manykin, E.A.; Ojovan, M.I.; Poluektov, P.P. (1994). "Impurity recombination of Rydberg matter". Journal of Experimental and Theoretical Physics. 78 (1): 27–32.
Holmlid, Leif (2002). "Conditions for forming Rydberg matter: condensation of Rydberg states in the gas phase versus at surfaces". Journal of Physics: Condensed Matter. 14 (49): 13469–13479. doi:10.1088/0953-8984/14/49/305.
Beigman, I.L; Lebedev, V.S (1995). "Collision theory of Rydberg atoms with neutral and charged particles". Physics Reports. Elsevier BV. 250 (3–5): 95–328. doi:10.1016/0370-1573(95)00074-q. ISSN 0370-1573.
L. Holmlid, "Redshifts in space caused by stimulated Raman scattering in cold intergalactic Rydberg Matter with experimental verification". J. Exp. Theor. Phys. JETP 100 (2005) 637–644.
Badiei, Shahriar; Holmlid, Leif (2002). "Magnetic field in the intracluster medium: Rydberg matter with almost free electrons". Monthly Notices of the Royal Astronomical Society. 335 (4): L94. Bibcode:2002MNRAS.335L..94B. doi:10.1046/j.1365-8711.2002.05911.x.
Wang, Jiaxi; Engvall, Klas; Holmlid, Leif (1999-01-08). "Cluster KN formation by Rydberg collision complex stabilization during scattering of a K beam off zirconia surfaces". The Journal of Chemical Physics. AIP Publishing. 110 (2): 1212–1220. doi:10.1063/1.478163. ISSN 0021-9606.
Svensson, Robert; Holmlid, Leif (1992). "Very low work function surfaces from condensed excited states: Rydberg matter of cesium". Surface Science. Elsevier BV. 269–270: 695–699. Bibcode:1992SurSc.269..695S. doi:10.1016/0039-6028(92)91335-9. ISSN 0039-6028.
Teo, Boon K. (2012). "Rydberg-Matter and Excited-State Clusters". Journal of Cluster Science. 23: 1. doi:10.1007/s10876-012-0449-z.
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States of matter (list)
State
Solid Liquid Gas / Vapor Plasma
Phase change
Low energy
Bose–Einstein condensate Fermionic condensate Degenerate matter Quantum Hall Rydberg matter Rydberg polaron Strange matter Superfluid Supersolid Photonic matter
High energy
QCD matter Lattice QCD Quark–gluon plasma Color-glass condensate Supercritical fluid
Other states
Colloid Glass Crystal Liquid crystal Time crystal Quantum spin liquid Exotic matter Programmable matter Dark matter Antimatter Magnetically ordered
Antiferromagnet Ferrimagnet Ferromagnet String-net liquid Superglass
Transitions
Boiling Boiling point Condensation Critical line Critical point Crystallization Deposition Evaporation Flash evaporation Freezing Chemical ionization Ionization Lambda point Melting Melting point Recombination Regelation Saturated fluid Sublimation Supercooling Triple point Vaporization Vitrification
Quantities
Enthalpy of fusion Enthalpy of sublimation Enthalpy of vaporization Latent heat Latent internal energy Trouton's ratio Volatility
Concepts
Baryonic matter Binodal Compressed fluid Cooling curve Equation of state Leidenfrost effect Macroscopic quantum phenomena Mpemba effect Order and disorder (physics) Spinodal Superconductivity Superheated vapor Superheating Thermo-dielectric effect
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