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单词 Franck condon principle
释义

Franck condon principle

中文百科

弗兰克-康登原理 Franck–Condon principle

（重定向自Franck condon principle）

弗兰克-康登原理（英语：Franck–Condon principle）是光谱学的重要原理，用于解释电子-振动跃迁的强度。电子-振动跃迁指分子吸收或发射光子后，电子能级和振动能级同时发生变化的过程。Franck-Condon原理指出，在分子电子跃迁过程中，当两个振动能级（分别属于不同的电子能级）的波函数有效重叠程度最大时，这两个振动能级之间的跃迁发生的概率最大。此原理可以被量子力学所解释。

英语百科

Franck–Condon principle 弗兰克-康登原理

（重定向自Franck condon principle）
Figure 1. Franck–Condon principle energy diagram. Since electronic transitions are very fast compared with nuclear motions, vibrational levels are favored when they correspond to a minimal change in the nuclear coordinates. The potential wells are shown favoring transitions between v = 0 and v = 2.
Figure 2. Schematic representation of the absorption and fluorescence spectra corresponding to the energy diagram in Figure 1. The symmetry is due to the equal shape of the ground and excited state potential wells. The narrow lines can usually only be observed in the spectra of dilute gases. The darker curves represent the inhomogeneous broadening of the same transitions as occurs in liquids and solids. Electronic transitions between the lowest vibrational levels of the electronic states (the 0–0 transition) have the same energy in both absorption and fluorescence.
Figure 3. Semiclassical pendulum analogy of the Franck-Condon principle. Vibronic transitions are allowed at the classical turning points because both the momentum and the nuclear coordinates correspond in the two represented energy levels. In this illustration, the 0–2 vibrational transitions are favored.
Figure 5. Figure 1 in Edward Condon's first publication on what is now the Franck–Condon principle [Condon 1926]. Condon chose to superimpose the potential curves to illustrate the method of estimating vibrational transitions.

The Franck–Condon principle is a rule in spectroscopy and quantum chemistry that explains the intensity of vibronic transitions. Vibronic transitions are the simultaneous changes in electronic and vibrational energy levels of a molecule due to the absorption or emission of a photon of the appropriate energy. The principle states that during an electronic transition, a change from one vibrational energy level to another will be more likely to happen if the two vibrational wave functions overlap more significantly.
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更新时间：2025/6/18 19:46:06