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分子中原子A的NMR化学位移可以表达为三项之和:σ~A=σ_d~A+σ_p~A+σ~(AB) (1)其中σ_d~A是反磁化学位移,σ_p~A是顺磁化学位移,σ~(AB)代表分子中其它原子B对于A的贡献的总和。对于自由原子,σ_d~A主要来自该原子实的贡献,价电子的贡献较小。而在分子中σ_d~A的变化(Δσ_d~A),却主要来自价电子的贡献。从X射线光电子能谱实验可以得到不同分子环境
The chemical shifts of the atoms A in a molecule can be expressed as the sum of three terms: σ ~ A = σ_d ~ A + σ_p ~ A + σ ~ AB where σ_d ~ A is the diamagnetic chemical shift and σ_p ~ A is Paramagnetic chemical shift, σ ~ (AB) represents the sum of the contribution of other atoms B in the molecule to A. For free atoms, σ_d ~ A mainly from the contribution of the atomic real, valence electron contribution is small. However, the change of σ_d ~ A in the molecule (Δσ_d ~ A) mainly comes from the valence electron contribution. From the X-ray photoelectron spectroscopy experiments can be different molecular environment