On the scattering of light by supersonic waves
On the scattering of light by supersonic waves
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DOI：
10.1073/pnas.18.6.409
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发表时间：
1932-01-01
影响因子：
11.1
通讯作者：
Sears, FW
中科院分区：
文献类型：
--
作者：
Debye, P;Sears, FW
1. 介绍。在1922年发表的一篇论文中，利昂·布里渊处理了光散射问题。对于低温，爱因斯坦的比热理论必须被德拜的理论所抛弃，根据这一事实，布里渊将物体的热密度波动归因于声波的叠加，在他的理论中，正如在爱因斯坦先前的理论中一样，2是声波散射的原因。他试图把他的理论结果应用于x射线散射的解释。我们现在知道这种应用是远远不正确的，因为对于这种短波，由于原子或分子结构引起的电子密度变化比热波动重要得多。然而，对于波长比分子距离长得多的光波，布里渊的分析得出了一些显著的结果。它们可以用下面的方式表示。假设原光入射。图1在这个方向上以长度为1的向量为特征的方向。假设散射光中有一部分沿另一个以单位矢量s为特征的方向传播，那么首先，在所有可能方向的声波中，只有沿矢量方向或相反方向传播的声波对散射是重要的= S-So。这也可以用这样的说法来表达，即声波的平面必须被置于这样的位置，即散射光可以被这些平面视为光学反射。但还有第二个限制。在所有方向为5的声波中，只有具有一定波长的声波才是有效的。这个波长是A= X/s，如果X是光的波长，s是矢量s的长度，等于2sin 0/2，称0为主光线和次光线之间的夹角。最后一个条件可以表示为：声波中最大密度的连续平面必须是
1. Introduction.-In a paper published in 1922 Leon Brillouin'treated the problem of light scattering. In accordance with the fact that for low temperatures Einstein's theory of specific heat has to be abandoned for Debye's theory, Brillouin attributes the thermal density fluctuations in the body, which, in his theory, as in a previous theory of Einstein's, 2 are responsible for the scattering to a superposition of sound waves. He tries to apply his theoretical results to the explanation of x-ray scattering. We knownow thatthis application is far from correct, as for such short waves the electronic density changes due to the atomic or molecular structure are much more important than the thermal fluctuations. For light waves, however, with a wave-length much longer than molecular distances, Brillouin's analysis leads to some remarkable results. They can bestated in the following manner. Suppose the primary light travels in. figure 1 in a directioncharacterized by a vector So of length unity in this direction. Let it be assumed that of the scattered light a part is observed traveling in another direction characterized by a unit vector S. Then firstly, of the sound waves of all possible directions, only those are important for the scattering which are traveling inor opposite to the direction of the vectors= S-So. This can also be expressed bysaying that the planes of the sound waves have to be situated such that the scattered light can be considered as optically reflected by these planes. But there is a second limitation. Of all the sound waves of direction s, only those of a definite wave-lengthA are effective. This wave-length is A= X/s, if X is the wave-length of the light and s is the length of the vector s, which is 2 sin 0/2, calling 0 the angle between the primary and the secondary ray. This last condition can be expressed by saying that the consecutiveplanes of maximum density in the sound wave must be