金黄色珍珠的光谱学特征

Spectral Characteristics of Golden Pearls

分别选取典型的天然金黄色珍珠与金黄色染色珍珠样品,在透射光下对比观察两种珍珠的表面特征,并采用激光拉曼光谱仪、紫外-可见-近红外分光光度计和荧光光谱仪对它们进行了测试分析。结果表明:金黄色染色珍珠的染色痕迹明显,有团块状、片状瑕疵;金黄色珍珠样品的拉曼光谱谱线稳定,具有典型的文石特征峰,而金黄色染色珍珠样品的拉曼光谱谱线起伏较大,除典型的文石特征峰外,杂峰与毛刺很多,荧光背景强度高;金黄色珍珠样品的紫外-可见-近红外反射光谱特征峰在355 nm附近,而金黄色染色珍珠样品的紫外-可见-近红外反射光谱除355 nm附近的特征峰外,还在450 nm附近有特征峰,应为外来无机或有机染料所致;金黄色珍珠有1个376 nm的激发波长光,表现在以472 nm为中心的发射光谱峰,而金黄色染色珍珠有2个激发波长光,受372 nm波长光激发的发射光谱峰以436 nm为中心,受450 nm波长光激发的发射光谱峰以493nm为中心。

In this paper,the surfaces of both typical golden pearls and dyed golden pearls were observed under the transparent light.The fluorescence spectra,Raman spectra and UV-Vis reflection spectra were employed to characterize them.The dyed golden pearls show obvious signs of dyeing with agglomerate or flake.In the Raman spectra,the stable typical aragonite peaks are observed for the golden pearl while there are many fluctuations with motley peaks and burrs for the dyed golden pearl.In addition,the characteristic peak of the golden pearl appears around 355 nm in the UV-Vis reflection spectra.However,there is an added peak around 450 nm besides the characteristic peak for the dyed golden pearl from the foreign inorganic or organic dyes.The golden pearl exhibits only one excitation at 376 nm showing the emission peak centering around 472 nm under the excitation at 376 nm UV light.However,the dyed golden pearl exhibits two excitations at 372 nm and 450 nm,respectively corresponding to the emission centers at 436 nm and 493 nm