Talk:Helium dimer
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 | A fact from Helium dimer appeared on Wikipedia's Main Page in the Did you know column on 23 February 2015 (check views). The text of the entry was as follows:
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Helium-3 Dimers
editIt appears that Helium-3 can form dimers: http://www.sciencedirect.com/science/article/pii/S0921452699026824 Can somebody verify that my reading of the article was correct?
If so, it contradicts the formation section. 192.12.88.232 (talk) 18:36, 22 April 2015 (UTC)
- In this case the situation is more complex than just two 3He atoms. They are surrounded by 4He atoms, and are somehow confined to a 2D skin, which probably means that they are also weakly bound to another surface. It is probably worth a mention in the article though. You are welcome to add something to the article. The article also mentions trapping two 3He atoms in a fullerene cage. This would correspond to a high pressure. Other unusual situations where they can be bound would be in an extremely strong magnetic field (eg on a neutron star) or high energy UV flux. I did not include these last two yet as not adequately supported by secondary sources. Graeme Bartlett (talk) 21:42, 22 April 2015 (UTC)
Bond length
editIt is currently written that "the He2 molecule has a large separation distance between the atoms of about 5200 pm." However, the equilibrium distance is known (see for instance J. Chem. Phys. 132, 204304 (2010)) to be 5.6 bohrs = 2.97 Angströms = 2970 pm. — Preceding unsigned comment added by 193.52.161.169 (talk) 08:39, 22 June 2017 (UTC)
- I assume you mean http://dx.doi.org/10.1063/1.3432250 or https://arxiv.org/pdf/1001.3268. This is a theoretical calculation. (Actually there are numerous calculations of this, and it is often a test of molecular bonding algorithms to see if they can come up with a sensible result.) The figure I put in the article is a measured result. Graeme Bartlett (talk) 11:25, 22 June 2017 (UTC)
- The value in the Monte Carlo article is the equilibrium bond length, not the vibrationally averaged one. They don't seem to include any sorts of nuclear dynamics in their study, only electronic structure. So not only a calculated results, but apples and oranges. 174.3.181.76 (talk) 15:59, 13 May 2018 (UTC)
How about He+
He−
?
edit
Because the first He would be H-like, and the other lithium-like. Alfa-ketosav (talk) 07:21, 3 December 2018 (UTC)
- If it was discovered it would be a very short lived excimer. Though I cannot find any studies of this. Graeme Bartlett (talk) 22:41, 3 December 2018 (UTC)
Strange wordings
editThere are a number of strange phrases in the article; I hope someone can improve them.
- Two excited helium atoms can react with a covalent bond....
What does it mean to say two atoms "react with a covalent bond"?
- The helium dication dimer He22+ is extremely repulsive....
What does it mean to say an ion is "repulsive"? What is it repelling?
- The dimer then explodes as two helium cations ions repel each other with the same speed but opposite directions.
What does it mean to say two things "repel each other with the same speed"? I fixed this one:
- The dimer then explodes as two helium cations repel each other, moving with the same speed but in opposite directions.
John Baez (talk) 22:33, 13 June 2024 (UTC)
- Two excited helium atoms can react with a covalent bond
- means a covalent bond can form
- The helium dication dimer He22+ is extremely repulsive..
- Means that the two atoms repel each other. They break apart in a "Coulomb explosion".
- Thanks for clarifying "repel each other with the same speed" Graeme Bartlett (talk) 06:23, 14 June 2024 (UTC)
- Thanks. I tried to fix the rest. John Baez (talk) 21:26, 14 June 2024 (UTC)
Contradictory data on bond energy
editThe cited value for the "binding energy" (not sure how this relates to BDE) is 1.1 times 10^-5 kcal/mol. This seems to contradict the next statement that the bond is 5000 times weaker than the bond in H-H. This also contradicts the data given in 10.1002/qua.20074, which is 0.021-0.022 kcal/mol (which actually *is* ~5000 smaller than the 104 kcal/mol of H2). Does anyone know why this might be? In my mind, binding energy (the amount of energy it takes the separate the assembly) should be the same as bond dissociation energy, but maybe there is some subtle difference here that I'm not aware of? Can a physical chemist address this? Alsosaid1987 (talk) 11:53, 29 September 2024 (UTC)