瑞利散射原理？

以下英文引自“Modern Raman Spectroscopy”，你的问题混淆了很多定义和概念，简单的说，散射分拉曼和瑞利，瑞利散射是光子和电子云的相互作用，不涉及偶极矩和极化率的变化，更不涉及能级变化（振动、电子能级等）。吸收和荧光则是分子内电子的实能级跃迁导致的（实能级与虚能级相对，或者你干脆当把“实能级看做能级好了”）。

The energy changes we detect in vibrational spectroscopy are those required to cause nuclear motion. If only electron cloud distortion is involved in scattering, the photons will be scattered with very small frequency changes, as the electrons are comparatively light. This scattering process is regarded as elastic scattering and is the dominant process. For molecules it is called Rayleigh scattering. However, if nuclear motion is induced during the scattering process, energy will be transferred either from the incident photon to the molecule or from the molecule to the scattered photon. In these cases the process is inelastic and the energy of the scattered photon is different from that of the incident photon by one vibrational unit. This is Raman scattering.

另外，偶极矩变化是红外光谱。荧光是电子从激发态没有完全回落至基态而产生的。这些都是需要分别讨论的。