紫色翡翠的谱学特征及颜色成因探讨

Study of Spectroscopical Characteristics and Coloring Factor of Lavender Jadeite

使用多种测试手段对热处理前后的缅甸深紫色翡翠样品进行测试。物相分析表明其属于硬玉型翡翠,X射线荧光光谱测试证明深紫色区域Mn、Fe含量高于白色区域,电子顺磁共振谱表明Mn主要以Mn3+形式存在,而非传统观点认为的Mn2+。热处理前后紫外-可见光吸收光谱表明,572 nm处宽吸收谱带应归因于Fe2+的5A1(5T2)→3T1(3H)跃迁以及Fe2+-Fe3+离子对间的电荷转移,这是紫色翡翠致色的主因。此外,Mn3+在545 nm处的6A1(S)→4T2(G)和6A1(S)→4T1(G)电子跃迁叠加是紫色翡翠致色的另一原因。

Different test methods are used for analyzing Burmese deep lavender color jadeite sample before and after heat treatment. Phase analysis shows that this kind of jadeite is assigned to jadeite jade. X- ray fluorescence spectrometry indicates that the deep lavender color area has more amount of Mn and Fe than the white one. Electron paramagnetic resonance spectra demonstrates that Mn mainly exists in the form of Mn3＋ rather than Mn2＋ in traditional opinions. Ultraviolet-visible absorption spectrum reveals that wide absorption band centered at 572 nm can be attributed Fe2＋ ion couple-electron pair ~Al（ST2）→3T1（3H） transition and the charge migration of Fe2＋-Fe3＋ ion pair, which are the main reasons for deep lavender jadeite coloring. The superposition of 6A1（S）→4T2（G） and 6A1（S）→4T1（G） d-d electron transition at 545 nm of Mn3＋ ion can be considered as another factor of lavender jadeite coloring.