SURFACE PLASMA OSCILLATIONS OF A DEGENERATE ELECTRON GAS
SURFACE PLASMA OSCILLATIONS OF A DEGENERATE ELECTRON GAS
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DOI：
10.1103/physrev.120.130
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发表时间：
1960-01-01
期刊：
影响因子：
--
通讯作者：
FERRELL, RA
中科院分区：
文献类型：
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作者：
STERN, EA;FERRELL, RA
继里奇之后，一些金属所表现出的能量低于等离子体激元能量的异常特征能量损失归因于简并电子气的量子化表面波。虽然里奇的理论已经被Powell和Swan通过高能电子的反射在理想的纯金属表面上得到了验证，但是透射实验显示出较低的能量损失。这是通过考虑金属表面上的氧化物涂层产生的弛豫来解释的。在这种方式中，实验数据是完全占没有任何异常的金属体介电性能的假设。本文研究了氧化物涂层厚度的依赖性，发现令人惊讶的薄涂层，例如仅20埃厚，可以产生显著的效果。它是建立在传输实验中的散射角与能量损失的色散的测量将产生氧化膜厚度的测量。进一步检查的理论建议通过测量的角度依赖性的强度的低特征能量损失。一个特殊的效果，预测非正常入射的快电子。应当发现，强度图案应当远离入射平面而闪烁。除了这些特殊的角度效应，据预测，由于表面等离子体振荡的敏感性，任何表面涂层的表面特征能量损失的值可以通过选择适当的涂层之间的宽的限制。特别地，制造两种不同金属的双层膜应在两种单独金属的体特征能量损失之间产生表面特征能量损失。
Following Ritchie, the anomalous characteristic energy losses of energy lower than the plasmon energy, exhibited by some metals, are attributed to quantized surface waves of the degenerate electron gas. Although Ritchie's theory has been verified for an ideal pure metal surface by Powell and Swan by reflection of high-energy electrons, the transmission experiments show a lower energy loss generally. This is accounted for by taking into account the relaxation produced by the oxide coating on the surface of the metal. In this way, the experimental data is completely accounted for without the assumption of any anomalous bulk dielectric properties of the metal. The present paper studies the dependence on thickness of the oxide coating, and it is found that a surprisingly thin coating, say only 20 angstroms thick, can produce a significant effect. It is established that a measurement of the dispersion of the energy loss versus angle of scattering in the transmission experiment would yield a measurement of the oxide film thickness. A further check on the theory is suggested by a measurement of the angular dependence of the intensity of the lowlying characteristic energy loss. A special effect is predicted for non-normally incident fast electrons. It should be found that the intensity pattern should flare away from the plane of incidence. Besides these special angular effects it is predicted that because of the sensitivity of the surface plasma oscillations to any surface coating the value of the surface characteristic energy loss can be varied between wide limits by choosing the appropriate coating. In particular, making double films of two different metals should produce surface characteristic energy losses in between the bulk characteristic energy losses of the two separate metals.