Diargon: Difference between revisions
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|D<sup>2</sup>Σ<sub>1/2u</sub><sup>+</sup>||Ar<sup>1</sup>S<sub>0</sub> + Ar<sup>+</sup><sup>2</sup>P<sub>1/2</sub> |
|D<sup>2</sup>Σ<sub>1/2u</sub><sup>+</sup>||Ar<sup>1</sup>S<sub>0</sub> + Ar<sup>+</sup><sup>2</sup>P<sub>1/2</sub> |
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|C<sup>2</sup>Π<sub>1/2u</sub>||Ar<sup>1</sup>S<sub>0</sub> + Ar<sup>+</sup><sup>2</sup>P<sub>1/2</sub>||128 004||58.9||1.4|| || || ||622 cm<sup>−1</sup>|| || || || ||<ref name="sign">{{cite journal|last1=Signorell|first1=R.|last2=Merkt|first2=F.|title=The first electronic states of Ar2+ studied by high resolution photoelectron spectroscopy|journal=The Journal of Chemical Physics|date=8 December 1998|volume=109|issue=22|pages=9762–9771|doi=10.1063/1.477646}}</ref> |
|C<sup>2</sup>Π<sub>1/2u</sub>||Ar<sup>1</sup>S<sub>0</sub> + Ar<sup>+</sup><sup>2</sup>P<sub>1/2</sub>||128 004||58.9||1.4|| || || || ||622 cm<sup>−1</sup>|| || || || ||<ref name="sign">{{cite journal|last1=Signorell|first1=R.|last2=Merkt|first2=F.|title=The first electronic states of Ar2+ studied by high resolution photoelectron spectroscopy|journal=The Journal of Chemical Physics|date=8 December 1998|volume=109|issue=22|pages=9762–9771|doi=10.1063/1.477646}}</ref> |
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|B<sup>2</sup>Π<sub>1/2g</sub>||Ar<sup>1</sup>S<sub>0</sub> + Ar<sup>+</sup><sup>2</sup>P<sub>3/2</sub> |
|B<sup>2</sup>Π<sub>1/2g</sub>||Ar<sup>1</sup>S<sub>0</sub> + Ar<sup>+</sup><sup>2</sup>P<sub>3/2</sub> |
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|C<sup>2</sup>Π<sub>3/2u</sub>||Ar<sup>1</sup>S<sub>0</sub> + Ar<sup>+</sup><sup>2</sup>P<sub>3/2</sub>||126884|| || || || || ||311 cm<sup>−1</sup>|| || || || ||<ref name="sign"/> |
|C<sup>2</sup>Π<sub>3/2u</sub>||Ar<sup>1</sup>S<sub>0</sub> + Ar<sup>+</sup><sup>2</sup>P<sub>3/2</sub>||126884|| || || || || || ||311 cm<sup>−1</sup>|| || || || ||<ref name="sign"/> |
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|B<sup>2</sup>Π<sub>3/2g</sub><sup>+</sup>||Ar<sup>1</sup>S<sub>0</sub> + Ar<sup>+</sup><sup>2</sup>P<sub>3/2</sub> || || |||| || || || ||0.104 eV|| || || || ||<ref name="prad">{{cite journal|last1=Pradeep|first1=T.|last2=Niu|first2=B.|last3=Shirley|first3=D. A.|title=Photoelectron spectroscopy of rare gas dimers revisited: Vibrationally resolved photoelectron spectrum of argon dimer|journal=The Journal of Chemical Physics|date=April 1993|volume=98|issue=7|pages=5269–5275|url=https://cloudfront.escholarship.org/dist/prd/content/qt9hv0n9tf/qt9hv0n9tf.pdf|doi=10.1063/1.464926}}</ref> |
|B<sup>2</sup>Π<sub>3/2g</sub><sup>+</sup>||Ar<sup>1</sup>S<sub>0</sub> + Ar<sup>+</sup><sup>2</sup>P<sub>3/2</sub> || || |||| || || || ||0.104 eV|| || || || ||<ref name="prad">{{cite journal|last1=Pradeep|first1=T.|last2=Niu|first2=B.|last3=Shirley|first3=D. A.|title=Photoelectron spectroscopy of rare gas dimers revisited: Vibrationally resolved photoelectron spectrum of argon dimer|journal=The Journal of Chemical Physics|date=April 1993|volume=98|issue=7|pages=5269–5275|url=https://cloudfront.escholarship.org/dist/prd/content/qt9hv0n9tf/qt9hv0n9tf.pdf|doi=10.1063/1.464926}}</ref> |
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Revision as of 11:38, 19 February 2018
| Names | |
|---|---|
| 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).
| |
Diargon or the argon dimer is a molecule containing two argon atoms. Normally this is only very weakly bound together by van der Waals forces. However in an excited state, or ionised state, the two atoms can be more tightly bound together, with significant spectral features. At cryogenic temperatures argon gas can have a few percent of diargon molecules.[1]
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] 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 theere are eight different vibration states. But if the molecule pins fast, vibration is more likely to shake it apart, and at the 30th rotational level there are only two stable and one metastable state of vibration. In combination there are 170 different possibilities that are stable. In the metastable states, energy will be released if the molecule breaks apart into two separate atoms, but some extra energy is required to overcome the attraction between the atoms. 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 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 | [5][1] |
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 | [4][3][7] |
References
- ^ a b c d e Ewing, George E. (June 1975). "Structure and Properties of van der Waals Molecules". Accounds of Chemical Research. 8 (6): 185–192.
- ^ Dehmer, P. M.; Pratt, S. T. (15 January 1982). "Photoionization of argon clusters". The Journal of Chemical Physics. 76 (2): 843–853. doi:10.1063/1.443056.
- ^ a b c Pradeep, T.; Niu, B.; Shirley, D. A. (April 1993). "Photoelectron spectroscopy of rare gas dimers revisited: Vibrationally resolved photoelectron spectrum of argon dimer" (PDF). The Journal of Chemical Physics. 98 (7): 5269–5275. doi:10.1063/1.464926.
- ^ a b Signorell, R.; Wüest, A.; Merkt, F. (22 December 1997). "The first adiabatic ionization potential of Ar2". The Journal of Chemical Physics. 107 (24): 10819–10822. doi:10.1063/1.474199.
- ^ a b Docken, Kate K.; Schafer, Trudy P. (June 1973). "Spectroscopic information on ground-state Ar2, Kr2, and Xe2 from interatomic potentials". Journal of Molecular Spectroscopy. 46 (3): 454–459. doi:10.1016/0022-2852(73)90057-X.
- ^ "Argon dimer". webbook.nist.gov. Retrieved 19 February 2018.
{{cite web}}: More than one of|work=and|website=specified (help) - ^ a b c Signorell, R.; Merkt, F. (8 December 1998). "The first electronic states of Ar2+ studied by high resolution photoelectron spectroscopy". The Journal of Chemical Physics. 109 (22): 9762–9771. doi:10.1063/1.477646.