Field emission and field ionization in condensed phases
Field emission and field ionization in condensed phases
复制标题
凝聚相场发射和场电离
DOI：
10.1021/ar50050a001
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发表时间：
1972
影响因子：
18.3
通讯作者：
R. Gomer
中科院分区：
文献类型：
--
作者：
R. Gomer
场发射是指在高电场的影响下从导体中产生电子隧道，从而使导体表面的势垒变形（图 1）。通常发生隧道效应的介质是真空；然而，在通常绝缘的液体中或通过发射极上吸附的类液体薄膜获得隧道效应是相当可行的。此类实验可以产生有关电子在凝聚相中的溶解热的信息。场电离由原子或分子的场发射组成，即在高场的影响下来自这些物质的电子的隧道效应。同样，通常在低压气体中进行的过程也可以在液体和薄膜中进行。然后它可以产生有关填充能级能量的信息，即此类介质的价带。液体中的场发射和场电离还提供液体中受控的高强度电子和正离子源，并容易产生电荷载流子的迁移率。此外，两者都揭示了许多通过其他方式很难或不可能看到的高场现象。通过提供准确已知的高场和极其良好表征的电极，它们还揭示了液体中的击穿现象。除了通过 Ne、Ar、Kr 和 Xe 层的场发射1 之外，本文的主题主要基于 Halpern 和作者的最新工作。 2·3 我们首先对基本理论进行一个非常简短的回顾。 4 就目前的目的而言，只需将金属视为势阱即可；由于不相容原理，每个平移能级只能有两个电子占据，这样势阱就会被填充到几个电子伏特的深度，如图1所示。最高的填充能级（费米能级）仍然比真空低几个电子伏特；这种能量势垒称为功函数。在热电子发射中，电子必须在该势垒上被激发；在场致发射中，强电场的施加使其变形，如图1b所示，使得电子可以隧道穿过由此产生的电势山。隧道概率 D 由罗伯特·戈默 (Robert Gomer) 给出，出生于奥地利维也纳。他于 1944 年在波莫纳学院获得学士学位，并在军队服役了两年，并于 1949 年在罗彻斯特大学获得博士学位。经过一年的博士后工作后，他加入了芝加哥大学，并一直在那里任教。他的研究兴趣集中在表面化学和物理学。本帐户的主题偏离了他的主要兴趣领域，但与其相关的不仅仅是实验方法，如电影部分所示。
Field emission consists of electron tunneling from a conductor under the influence of a high applied electric field, which deforms the potential barrier at its surface (Figure 1). Usually the medium into which tunneling occurs is a vacuum; it is quite feasible, however, to ob-tain tunneling into normally insulating liquids or through liquid-like films adsorbed on the emitter. Such experiments can yield information on the heat of solu-tion of electrons in condensed phases. Field ionization consists of field emission from atoms or molecules, ie, tunneling of electrons from these species under the in-fluence of high fields. Again the process, normally car-ried out in a low-pressure gas, can occur in liquids and films. It can then yield information on the energy of filled levels, ie, the valence bands of such media. Field emission and field ionization in liquids also provide controlled high-intensity sources of electrons and positive ions in liquids and readily yield the mobilities of the charge carriers. In addition, both reveal a num-ber of high-field phenomena difficult or impossible to see by other means. By providing accurately known high fields and extremely well-characterized electrodes, they also shed light on breakdown phenomena in liquids. With the exception of field emission through Ne, Ar, Kr, and Xe layers1 the subject matter of this paper is based mainly on recent work of Halpern and the author. 2· 3 We start with a very brief reviewof basic theory. 4 For present purposes it suffices to consider a metal as a potential well; because of the exclusion principle, only two electrons can occupy each translational level, so that the well will be filled to a depth of several electron volts, as shown in Figure 1. The highest filled level (Fermi level) is still several electron volts below the vacuum; this energy barrier is calledthe work function,. In thermionic emission electrons must be ex-cited over this barrier; in field emission theapplication of a strong electric field deforms it, as shown in Figure lb, so that electrons can tunnel through the resultant po-tential hill. The tunneling probability D is given withRobert Gomer was born in Vienna, Austria. He received his BA from Pomona College in 1944> spent two years in the Army, and re-ceived his Ph. D. from The University of Rochester in 1949. After a year's postdoctoral work, he joined the staff at The University of Chicago, where he has been teaching since. His research interests center on the chemistry and physics of surfaces. The subject of this Account is a departure from his main field of interest, but is related to it by more than experimental method, as the section on films indicates.