6种不同产地柯巴树脂的谱学特征探究

收集了来自俄罗斯、新西兰、婆罗洲、马达加斯加、哥伦比亚和苏门答腊6个不同产地的柯巴树脂,采用宝石显微镜、红外光谱、紫外荧光观察和三维荧光光谱等测试方法对柯巴树脂谱学特征进行了对比研究。婆罗洲、苏门答腊柯巴树脂的红外光谱主要特征为存在3000~2800 cm^-1范围内4个吸收峰,1732 cm^-1肩峰和1708 cm^-1吸收峰,888 cm^-1处的弱吸收峰。新西兰柯巴树脂红外光谱主要特征为存在3000~2800 cm^-1范围内3个吸收峰,1642 cm^-1和888 cm^-1处的弱吸收峰。马达加斯加、哥伦比亚和俄罗斯柯巴树脂的红外光谱相似,主要特征为存在与C=C相关的3处组合特征吸收峰以及1270 cm^-1和1180 cm^-1处的2个吸收峰。在长波紫外荧光下,婆罗洲和新西兰柯巴树脂荧光强度明显强于其他产地样品,马达加斯加柯巴树脂荧光强度最弱。由三维荧光光谱可知,婆罗洲和苏门答腊柯巴树脂中存在445、474、505 nm 3个发射峰,可被416、447 nm波长有效激发;新西兰柯巴树脂的最强发射峰位于385 nm,其最佳激发波长352 nm;俄罗斯柯巴树脂最强发射峰在399 nm,可被354 nm波长最佳激发;哥伦比亚柯巴树脂的最强发射峰为470 nm,被400 nm波长最佳激发;马达加斯加柯巴树脂的最强荧光峰在465 nm,被378 nm波长最佳激发。综合分析认为,三维荧光光谱特征和红外光谱特征可为柯巴树脂的鉴别和分类提供依据。

Spectroscopic characteristics of copal resins from six different origins

This paper presents a comparative study of the spectral characteristics of copal resins from six different origins: Russia, New Zealand, Borneo, Madagascar, Colombia, and Sumatra. The study uses gemstone microscopy, infrared spectroscopy, ultraviolet fluorescence observation, and three-dimensional fluorescence spectroscopy to identify the characteristics of the resins. The results indicate that the infrared spectra of Borneo and Sumatra copal resins are mainly characterized by four absorption peaks in the range of 3000~2800 cm^-1, absorption peaks at 1708 cm^-1 and a shoulder peak at 1732 cm^-1, a weak absorption peak at 888 cm^-1. Similarly, the main features of the infrared spectra of New Zealand copal resin are three absorption peaks in the range of 3000~2800 cm^-1 and weak absorption peaks at 1 642 and 888 cm^-1. The infrared spectra of copal resins from Madagascar, Colombia, and Russia exhibit similarities, with three combined characteristic absorption peaks associated with C=C, a strong absorption peak at 1 692 cm^-1, and two absorption peaks of comparable intensity at 1270 and 1180 cm^-1. Under long-wave UV fluorescence, the fluorescence intensity of Borneo and New Zealand copal is stronger than that of resins from other origins, but the fluorescence intensity of Borneo copal is significantly stronger and the fluorescence intensity of Madagascar copal is the weakest. Borneo and Sumatra copal resins emit three typical peaks at 445, 474 and 505 nm, which can be optimally excited by 416,447 nm. The strongest emission peak of New Zealand copal is at 385 nm, which can be best excited by 352 nm. The strongest emission peak of Russian copal is at 399 nm, which can be best excited by 354 nm. The strongest emission peak of Colombian copal is centered at 470 nm, which can be best excited by 400 nm; and the relative fluorescence intensity of Madagascar copal is the weakest, the strongest fluorescence peak is at 465 nm, which can be best excited by 378 nm. It was concluded that the fluorescence and infrared spectroscopic characteristics of the copal resin could provide a basis for the identification and classification of the resin.