The conduction band and ultra-violet absorption of alkali-halide crystals.
The conduction band and ultra-violet absorption of alkali-halide crystals.
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DOI：
10.1039/tf9383400500
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发表时间：
1938-01-01
影响因子：
--
通讯作者：
Mott, NF
中科院分区：
文献类型：
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作者：
Mott, NF
固体理论的一个众所周知的结果是，在绝缘体中存在允许能级的能带，这些能带通常是未被占据的;然而，当电子通过吸收光而被提升到这些能级时，晶体可以导电。为了各种目的，重要的是要知道这些能级中最低能级的能量x，相对于晶体外静止电子的能量。本文的目的是估算碱金属卤化物晶体的这种能量。当然，用维格纳和其他人为研究金属能带而发展的波动力学方法，直接计算这种能量在原则上是可能的。提布斯最近曾尝试过这样的计算;然而，结果非常敏感地依赖于构成晶体的离子的波函数，因此不太可靠。因此，在本文中，我们尝试用三种不同的方法从实验中推导出导电能级的位置。前两个依赖于碱金属卤化物的紫外吸收光谱的解释。因此，我们开始讨论这些光谱。
It is a well-known result of the theory of solids that in insulators there are bands of allowed energy levels which are normally unoccupied; when, however, electrons are raised to these levels by the absorption of light the crystal can conduct. For various purposes it is important to know the energy x of the lowest of these energy levels, relative to the energy of an electron at rest outside the crystal. It is the purpose of this paper to estimate this energy for the alkali-halide crystals. A direct calculation of this energy, using the methods of wave mechanics developed by Wigner and others for investigatiog the energy bands in metals is, of course, possible in principle. Such a calculation has recently been attempted by Tibbs; the results, however, depend very sensitively on the wave functions used for the ions of which the crystals are built up, and are therefore not very reliable. In this paper, therefore, we attempt in three different ways to deduce the position of the conduction level from experiment. The first two depend on the interpretation of the ultra-violet absorption spectra of the alkali-halides. We therefore begin with a discussion of these spectra.