And He2 plus is observed in helium plasmas at high pressure, He2 but not neutral He2.

因此He2+能在高压的氦气等离子体中,被观察到，而不是中性的。

麻省理工公开课 - 固态化学导论课程节选

And there's actually a way that we can make predictions here, and what I'll tell you is molecular orbital theory predicts that h e 2 does not exist because it's not stabilized in terms of forming the molecule.

其实我们有一种办法可以做出预测，我要告诉你们的是分子轨道,理论预测He2不存在,因为它形成分子不稳定。

麻省理工公开课 - 化学原理课程节选

Now let's go and fill the molecular states for the putative He2.

现在我们要填充分子状态,对于假定的He2来说。

麻省理工公开课 - 固态化学导论课程节选

So our bond order for h e 2 is going to be equal to 0.

所以He2的键序等于0。

麻省理工公开课 - 化学原理课程节选

Let's draw the molecular diagram for h e 2 now.

让我们画一下He2的分子图。

麻省理工公开课 - 化学原理课程节选

So it has a bond, there's no bond in h e 2.

所以在He2里没有键。

麻省理工公开课 - 化学原理课程节选

And so He2 unstable.

因此He2，不稳定。

麻省理工公开课 - 固态化学导论课程节选

So I guess we'll start with helium 2.

我们从He2开始。

麻省理工公开课 - 化学原理课程节选

Now, He2, stable or not?

现在He2，稳定吗？

麻省理工公开课 - 固态化学导论课程节选

So we can compare the two electron configurations, and we can actually think about what we figure out from them, we see that two are lowered in energy, two electrons are raised in energy, so we have no net gain or no net loss in energy for h e 2.

我们可以比较两种电子构型，我们可以考虑,我们发现这，两个电子能量变低，两个电子能量升高，所以在He2里没有净的能量得失。

麻省理工公开课 - 化学原理课程节选

So what actually turns out the reality is that h e 2 does exist, but it exists as the weakest chemical bond known, and it wasn't, in fact, even found to exist until 1993, so I can assure you this is not a bond that you see very often in nature, and it is a very, very weak bond.

实际上He2键是存在的，但它是目前所知的最弱的键，直到1993年它才被发现，所以我可以向你们保证在,自然界你们不可能经常看到它，它是种非常非常弱得键。

麻省理工公开课 - 化学原理课程节选