近边X射线吸收精细结构光谱法研究土壤腐殖质组分含碳官能团组成及磷酸根影响

应用同步辐射近边X射线吸收精细结构(NEXAFS)光谱技术研究了土壤腐殖质各组分(富里酸、胡敏酸及胡敏素等)的含碳官能团组成信息,并通过分析PO43-存在条件下胡敏酸、胡敏素的官能团组成变化特征,探讨了PO43-与土壤腐殖质之间的微观作用机制。结果表明,土壤腐殖质不同组分的官能团分布具有类似的光谱特征,但组成比例存在明显差异。随着腐殖质组分的酸不溶性增加,胡敏酸、胡敏素疏水性脂肪基官能团比例显著高于富里酸,芳构化程度也明显增加,而亲水性羧基官能团比例趋于降低;PO43-通过静电作用、取代反应可以选择性释放胡敏酸中部分小分子羧基官能团,从而改变胡敏酸官能团的组成特征。此研究结果对于应用NEXAFS研究有机碳官能团形态、结构及理解PO43-在土壤微界面上的反应机制具有重要意义。     

Path integral approach to electron scattering in classical electromagnetic potential

As is known to all, the electron scattering in classical electromagnetic potential is one of the most widespread applications of quantum theory. Nevertheless, many discussions about electron scattering are based upon single-particle Schrodinger equation or Dirac equation in quantum mechanics rather than the method of quantum field theory. In this paper, by using the path integral approach of quantum field theory, we perturbatively evaluate the scattering amplitude up to the second order for the electron scattering by the classical electromagnetic potential. The results we derive are convenient to apply to all sorts of potential forms. Furthermore, by means of the obtained results, we give explicit calculations for the one-dimensional electric potential.