On the transformation of light into heat in solids. I
On the transformation of light into heat in solids. I
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DOI：
10.1103/physrev.37.17
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发表时间：
1931-01-01
期刊：
影响因子：
--
通讯作者：
Frenkel, J
中科院分区：
文献类型：
--
作者：
Frenkel, J
从晶体和分子的类比出发，表明光吸收过程中第一步的电子激发并不局限于特定的原子，而是以“激发波”的形式在所有原子之间稀释，类似于用于描述同一晶体中热运动的声波。由于原子之间的相互作用，激发态被分成子状态，其数量等于原子数 n（激发多重态）。通过叠加几个激发波，可以构建代表激发态从一个原子到另一个原子的传播的“激发包”。每个激发子态都对应一个与正常晶体结构略有不同的确定的晶体结构（晶格常数、振动频率），并产生略有不同的振动态。激发对振动状态的这种影响提供了它们之间的间接耦合，这使得激发能量可以在数百个热振荡器之间共享，而在形成光吸收过程的第二状态的无辐射跃迁中几乎没有直接耦合或非和谐性。
Starting from the analogy between a crystal and molecule, it is shown that the electronic excitation, forming the first step in the process of light absorption, is not confined to a particular atom, but is diluted between all of them in the form of" excitation waves," similar to sound waves which are used to describe the heat motion in the same crystal. Owing to the interaction between the atoms the excitation state is split up into substates whose number is equal to the number of atoms n (excitation multiplet). By superposing several excitation waves" excitation packets" can be constructed representing the travelling of the excitation state from one atom to another. To each excitation sub-state there corresponds a definite crystal structure (lattice constant, vibration frequencies) slightly different from that of the normal, and giving rise to slightly different vibrational states. This influence of the excitation on the vibrational states provides an indirect coupling between them, which allows the excitation energy to be shared between a few hundred heat-oscillators with practically no direct coupling nor anharmonicity in a radiationless transition which forms the second state of the process of light absorption.