不同处理工艺对珍珠的紫外可见漫反射光谱的共性影响研究

主要基于紫外可见（UV-Vis）漫反射光谱首次对比研究了经过热处理、有机或无机染料改色或钴-60产生的γ射线辐照三种不同处理工艺对同为珍珠质的淡水与海水珍珠及贝壳珍珠层的漫反射光谱的影响机制。结果表明：（1）在不同颜色、淡海水属性的珍珠与贝壳珍珠层的UV-Vis反射光谱的紫外区皆存在约280 nm 处的吸收峰，上述吸收峰位归属于珍珠层中自身存在的有机质所致，而非珍珠的致色色素。（2）以上三种不同的处理工艺对上述280 nm处的吸收峰位存在一致的影响行为，即随着不同的处理工艺强度的增大，处理样品对应的反射谱图中约280 nm处吸收峰的强度逐渐降低直至消失。与此同时，珍珠的反射谱图中紫外区的反射主波长的反射强度也随之减弱，且反射主波长的峰位向可见光区发生显著红移。研究工作可为珍珠及珍珠的优化处理的鉴定筛选及其珍珠颜色的形成属性判定提供检测依据与理论支撑。

Study on the Common Effect of Heat Treatment,Dyeing or Irradiation Treatment on UV-Vis Diffuse Reflectance Spectra of Pearls

The effects of heat treatment, dyeing treatment with organic or inorganic dyes and Co60-γ ray irradiation treatment on the reflection spectra of freshwater or seawater cultured pearls and shells were comparatively investigated mainly by UV-Vis diffuse reflection spectrometer, respectively. The results show that: (1) these three different kinds of treatment have a clear common effect on the absorption peak of 280 nm in the reflection spectra of the nacre of pearls and shells. Furthermore, the absorption located at 280 nm is attributed to the organic matrix, which is one of the important components of nacre from pearls, and it is not directly responsible for coloring of colored pearls. (2) It is clearly seen that the intensity of the above absorption peak gradually reduces until it disappear with the increase of intensity of different treatment process. Furthermore, the intensity of the main wavelength of the reflection peak weakened gradually in the ultraviolet region of diffuse reflection spectra, and red-shifted toward the visible light. To sum up, this present study may provide the basis and theoretical support for the investigation of the coloring mechanism and identification of pearls and the corresponding treated ones.