Chemistry. Extracting potentials from spectra.
Chemistry. Extracting potentials from spectra.
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化学。
DOI：
10.1126/science.1175751
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发表时间：
2009
期刊：
影响因子：
--
通讯作者：
Bernath PF
中科院分区：
文献类型：
--
作者：
Bernath PF
对于大多数元素，我们知道它们是否可以形成双原子分子，特别是对于电子很少、理论上很容易处理的轻原子。但对于这样一种轻松的元素，惊喜仍在后头。在20世纪的大部分时间里，实验和理论研究都认为铍二聚体(Be2)是不存在的。Be原子充满了电子壳层，就像惰性气体如氦一样，预计在非常大的核间距离下最多只能形成一个微弱的范德华二聚体。然而，正如Merrittet等人在本期第1548页上实验表明的那样，Be2确实存在，并且具有相对较短的键(2.45Å)，相对于预期的约5Å的范德华络合物。它异常平坦的势能曲线限制了振动能级的数量，并为研究分子在解离极限时的最高振动状态提供了难得的机会。
For most elements, we know whether they can form a diatomic molecule, especially for light atoms that have few electrons and can be treated readily by theory. But for one such light element, surprises are still in store. For most of the 20th century, experimental and theoretical studies agreed that the beryllium dimer (Be2) did not exist. The Be atom has filled electron shells and—like the inert gases such as helium—was expected to form at most a weak van der Waals dimer at very large internuclear distances. Yet, as shown experimentally by Merrittet al.on page 1548 of this issue , Be2does exist and has a relatively short bond (2.45 Å), relative to the anticipated van der Waals complex with a bond length of about 5 Å. Its unusually flat potential curve limits the number of vibrational levels and provides the rare opportunity to study the highest vibrational state of a molecule just at its dissociation limit.