天然金色海水养殖珍珠的微结构及其紫外-可见谱图特征研究

Study on Microstructure and UV-V_(is) Spectra Characteristics of Natural-Color Golden Seawater Cultured Pearl

通过对不同直径大小、不同金色深浅的天然金色海水养殖珍珠的紫外-可见(UV-Vis)吸收光谱、珍珠层微纳米结构的扫描电子显微镜(SEM)与高分辨透射电镜(HR-TEM)分析及珍珠层厚度进行对比性研究,并探究了金珠颜色的深浅与珍珠层厚度间的联系及金珠独特的UV-Vis谱图成因。结果表明:金珠的颜色越深,对应的UV-Vis特征吸收峰的强度越大,但金珠珍珠层的厚度与金珠金色的深浅不存在正相关性;在同一颗金珠中不同区域的珍珠层的厚度、珍珠层表面的"叠瓦状"结构的疏密程度存在显著差异,推测上述差异可能是导致金珠的UV-Vis吸收光谱存在区域差异性的影响因素;此外,在珍珠层中存在典型的准一维光子带隙结构,该结构应与金珠的呈色或呈色深浅有密切的关联。

A comparative studies on the morphology of micro/nano-structure, the thickness of nacreous layer of natural-color golden seawater cultured pearl with different diameters and golden shades are carried out by ultra-violet and visible （UV-Vis） absorption spectrum, scanning electron microscopy （SEM） and high resolution transmission electronmicroscopy （HR-TEM）. Furthermore, the relations between the thickness of nacreous layer and the color and the unique characteristic of UV-Vis spectra are further discussed. The results show that： the intensity of absorption band in UV-Vis absorption spectra is increasing as the deep color of golden-color pearl, the deep or light color of golden-color pearl has no direct relation with the thickness of nacreous layer. It is found that the thickness of nacreous layer located in different regions on the surface of golden-color pearl is different. Meanwhile, the density of “imbricate” structure and the morphology of the surface of golden-color pearl are different. The above characteristics maybe result to the slight varied UV-Vis absorption spectra with different regions on the surface of nacreous layer. In addition, one dimensional quasi-photonic bad gap structure exists in the nacreous layer of golden-color pearl, which should have close relations with the coloring of golden pearl and the density of golden-color.