Diargon
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| Names | |
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| Other names
argon dimer
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| Identifiers | |
3D model (
JSmol ) |
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PubChem CID
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| Properties | |
| Ar2 | |
| Molar mass | 79.896 g·mol−1 |
| Appearance | transparent gas |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Diargon or the argon dimer is a
cryogenic temperatures, argon gas can have a few percent of diargon molecules.[1]
Theory
Two argon atoms are attracted together by
rotating molecule, the centrifugal force
drags the atoms apart, but can still be overcome by the attractive force. But if the rotation is too much the atoms break apart.
Properties
The
ionisation energy of the neutral molecule is 14.4558 eV (or 116593 cm−1).[2]
The
dissociation energy of neutral Ar2 in the ground state is 98.7 cm−1[3] which is hundreds of times weaker than that of typical molecules.[1] The dissociation energy of Ar2+ is 1.3144 eV or 10601 cm−1.[4]
The Ar2 molecule can exist in a number of different vibration and rotational states. If the molecule is not rotating, there are eight different vibration states. But if the molecule spins fast, vibration is more likely to shake it apart, and at the 30th rotational level there are only two stable and one
Quantum tunneling can result in the molecule breaking apart with no extra energy. However this takes time, which can vary from 10−11 seconds to several centuries.[1] Molecules crashing into each other also results in breakup of the van der Waals molecules. At standard conditions this only takes about 100 picoseconds.[1]
Excited states
Neutral
99.6% of the
argon isotopes are 40Ar, so the spectrum observed in natural argon dimer will be due to the 40Ar40Ar isotopomer.[5] The following table lists different excited states.[6]
| Parameter | Te | ωe | ωexe | ωeye | Be | αe | γe | De | βe | re | ν00 | Re Å | ref |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| H | 112033.9 | ||||||||||||
| G | 110930.9 | ||||||||||||
| F 0+ g |
108492.2 | ||||||||||||
| E | 107330 | ||||||||||||
| D | 106029.5 | ||||||||||||
| C 0+ g |
95050.7 | ||||||||||||
| B1Σu+ 0+ g |
93241.26 | ||||||||||||
| A3Σ2u+1u | 92393.3 | ||||||||||||
| X1Σg+ | 31.92 | 3.31 | 0.11 | 0.060 | 0.004 | 76.9 | 3.8 | [1][5] |
Cation
| Parameter | breakup | Te | ωe | ωexe | ωeye | Be | αe | γe | De | βe | re | ν00 | Re Å | ref |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| D2Σ1/2u+ | Ar1S0 + Ar+2P1/2 | |||||||||||||
| C2Π1/2u | Ar1S0 + Ar+2P1/2 | 128 004 | 58.9 | 1.4 | 622 cm−1 | [7] | ||||||||
| B2Π1/2g | Ar1S0 + Ar+2P3/2 | |||||||||||||
| C2Π3/2u | Ar1S0 + Ar+2P3/2 | 126884 | 311 cm−1 | [7] | ||||||||||
| B2Π3/2g+ | Ar1S0 + Ar+2P3/2 | 0.104 eV | [3] | |||||||||||
| A2Σ1/2u+ | Ar1S0 + Ar+2P3/2 | 116591 | 307.0 | 2.05 | 622 cm−1 ?1.361 eV | [3][4][7] |
References
- ^ .
- doi:10.1063/1.443056.
- ^ S2CID 96815402.
- ^ doi:10.1063/1.474199.
- ^ .
- ^ "Argon dimer". NIST Standard Reference Database 69: NIST Chemistry WebBook. Retrieved 19 February 2018.
- ^ doi:10.1063/1.477646.
Extra references
 | This 'further reading' section may need cleanup. (October 2020) |
- Parson, J.M.; Siska, P.E.; Lee, Y.T., Intermolecular potentials from crossed-beam differential elastic scattering measurements. IV. Ar + Ar, J. Chem. Phys., 1972, 56, 1511.
- LeRoy, R.J., Improved spectroscopic dissociation energy for ground-state Ar2, J. Chem. Phys., 1972, 57, 573.
- Present, R.D., Collision diameter and well depth of the Ar-Ar interaction, J. Chem. Phys., 1973, 58, 2659.
- Wilkinson, P.G., Absorption spectrum of argon in the 1070–1135 Å region, Can. J. Phys., 1968, 46, 315.
- Tanaka, Y.; Yoshino, K., Absorption spectrum of the argon molecule in the vacuum-UV region, J. Chem. Phys., 1970, 53, 2012.
- Colbourn, E.A.; Douglas, A.E., The spectrum and ground state potential curve of Ar2, J. Chem. Phys., 1976, 65, 1741.
- Huffman, R.E.; Larrabee, J.C.; Tanaka, Y., Rare gas continuum light sources for photoelectric scanning in the vacuum ultraviolet, Appl. Opt., 1965, 4, 1581.
- Wilkinson, P.G., The mechanism of the argon emission continuum in the vacuum ultraviolet. I, Can. J. Phys., 1967, 45, 1715.
- Tanaka, Y., Continuous emission spectra of rare gases in the vacuum ultraviolet region, J. Opt. Soc. Am., 1955, 45, 710.
- Strickler, T.D.; Arakawa, E.T., Optical emission from argon excited by alpha particles: quenching studies, J. Chem. Phys., 1964, 41, 1783.
- Verkhovtseva, E.T.; Fogel, Ya.M.; Osyka, V.S., On the continuous spectra of inert gases in the vacuum-ultraviolet region obtained by means of a gas-jet source, Opt. Spectrosc. Engl. Transl., 1968, 25, 238, In original 440.
- Hurst, G.S.; Bortner, T.E.; Strickler, T.D., Proton excitation of the argon atom, Phys. Rev., 1969, 178, 4.
- Tanaka, Y.; Jursa, A.S.; LeBlanc, F.J., Continuous emission spectra of rare gases in the vacuum ultraviolet region. II. Neon and helium, J. Opt. Soc. Am., 1958, 48, 304. Michaelson, R.C.; Smith, A.L., Potential curves from emission continua. IV. The upper state of the vacuum uv contiua of Ar2, J. Chem. Phys., 1974, 61, 2566. [all data]
- Morgan, C.E.; Frommhold, L., Raman spectra of van der Waals dimers in argon, Phys. Rev. Lett., 1972, 29, 1053.
- Frommhold, L.; Bain, R., Comments concerning the "Raman spectra of van der Waals dimers in argon", J. Chem. Phys., 1975, 63, 1700.
- Cavallini, M.; Gallinaro, G.; Meneghetti, L.; Scoles, G.; Valbusa, U., Rainbow scattering and the intermolecular potential of argon, Chem. Phys. Lett., 1970, 7, 303.
- Barker, J.A.; Fisher, R.A.; Watts, R.O., Liquid argon: Monte Carlo and molecular dynamics calculations, Mol. Phys., 1971, 21, 657.
- Maitland, G.C.; Smith, E.B., The intermolecular pair potential of argon, Mol. Phys., 1971, 22, 861.
- Present, R.D., Collision diameter and well depth of the Ar-Ar interaction, J. Chem. Phys., 1973, 58, 2659.
- Photoionization of Ar2 at high resolution The Journal of Chemical Physics 76, 1263 (1982); https://doi.org/10.1063/1.443144 P. M. Dehmer
- spectrum 800 to 850Å
- Ab initio pair potential energy curve for the argon atom pair and thermophysical properties for the dilute argon gas. II. Thermophysical properties for low-density argon Eckhard Vogel, Benjamin Jäger, Robert Hellmann & Eckard Bich Pages 3335–3352 Published 07 Oct 2010 https://doi.org/10.1080/00268976.2010.507557 (will use the formula and draw graph)
- Accurate ab initio potential for argon dimer including highly repulsive region Konrad Patkowski, Garold Murdachaew, Cheng-Ming Fou & Krzysztof Szalewicz Pages 2031–2045 Accepted 12 Sep 2004, Published online: 21 Feb 2007 https://doi.org/10.1080/00268970500130241
- The spectrum and ground state potential curve of Ar2 The Journal of Chemical Physics 65, 1741 (1976); https://doi.org/10.1063/1.433319 E. A. Colbourn and A. E. Douglas
- The intermolecular pair potential of argon G.C. Maitland & E.B. Smith Pages 861–868 | Received 27 Oct 1971 https://doi.org/10.1080/00268977100103181 Molecular Physics An International Journal at the Interface Between Chemistry and Physics Volume 22, 1971 – Issue 5
- The Journal of Chemical Physics > Volume 61, Issue 8 Interpretation of Raman spectra of van der Waals dimers in argon The Journal of Chemical Physics 61, 2996 (1974); https://doi.org/10.1063/1.1682453 Lothar Frommhold
- Volume 23, Issue 5, May 1980, Pages 499–502 Journal of Quantitative Spectroscopy and Radiative Transfer On the Hulburt-Hirschfelder potential function for the Ar2 molecule Swadesh Kumar Ghoshal; Sankar Sengupta https://doi.org/10.1016/0022-4073(80)90052-7
- Volume 71, Issue 4 > 10.1063/1.438529 Emission spectrum of rare gas dimers in the vacuum UV region. II. Rotational analysis of band system I of Ar2 The Journal of Chemical Physics 71, 1780 (1979); https://doi.org/10.1063/1.438529 D. E. Freeman, K. Yoshino, and Y. Tanakam (1073.5–1081.5 Å)
- Imaging of the Structure of the Argon and Neon Dimer, Trimer, and Tetramer B. Ulrich, A. Vredenborg, A. Malakzadeh†, L. Ph. H. Schmidt, T. Havermeier, M. Meckel†, K. Cole, M. Smolarski‡, Z. Chang, T. Jahnke, and R. Dörner J. Phys. Chem. A, 2011, 115 (25), pp 6936–6941 DOI: 10.1021/jp1121245 http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.661.7525&rep=rep1&type=pdf
- Experimental evidence for two decay channels in electron impact ionization and fragmentation of argon dimer Elias Jabbour Al Maalouf1, Xueguang Ren2,3, Alexander Dorn2 and Stephan Denifl Journal of Physics: Conference Series, Volume 635, Lepton – Molecule and Small Cluster http://iopscience.iop.org/article/10.1088/1742-6596/635/7/072062/pdf
- Raman studies of argon dimers in a supersonic expansion. I. Spectroscopy H. P. Godfried and Isaac F. Silvera Phys. Rev. A 27, 3008 – Published 1 June 1983https://pure.uva.nl/ws/files/2168366/46711_214418y.pdf https://doi.org/10.1103/PhysRevA.27.3008
- Observation of dissociative recombination of Ne+2 and Ar+2 directly to the ground state of the product atoms G. B. Ramos, M. Schlamkowitz, J. Sheldon, K. A. Hardy, and J. R. Peterson Phys. Rev. A 51, 2945 – Published 1 April 1995 https://doi.org/10.1103/PhysRevA.51.2945
- Dissociative recombination studies of Ar+2 by time-of-flight spectroscopy G. B. Ramos, M. Schlamkowitz, J. Sheldon, K. Hardy, and J. R. Peterson Phys. Rev. A 52, 4556 – Published 1 December 1995 https://doi.org/10.1103/PhysRevA.52.4556