采用傅里叶变换红外光谱仪并配合固体高分辨核磁共振波谱仪,对不同产地的琥珀和柯巴树脂的红外光谱(FTIR)和核磁共振谱(^13 C NMR)进行了测试与分析。结果表明,由C—H饱和键伸缩振动致红外吸收强谱带致2 930,2 870cm^-1红外吸收强谱带,与之对应的CH2—CH3弯曲振动致1 460-1 443cm^-1和1 384-1 375cm^-1红外吸收中强谱带,为不同产地琥珀的特征红外光谱;与琥珀相比较,柯巴树脂所特有的吸收谱峰为由C═CH2反对称伸缩振动致红外吸收弱谱带3 080cm^-1,C═C伸缩振动致红外吸收谱带1 645cm^-1和C—H面外变形振动致红外吸收谱带890cm^-1;分析不同产地琥珀的FTIR和13 C NMR谱学表征,其相对石化成熟度亦有差异,缅甸琥珀、辽宁琥珀、多米尼加琥珀、墨西哥琥珀的相对年龄依次变新,且δ=14×10^-6~18×10^-6和δ=215×10^-6~220×10^-6处的13 C NMR共振谱峰仅出现在柯巴树脂中,表明其石化成熟度相对偏低。文中对不同产地琥珀的谱学表征差异与其石化程度的关系及其意义一并给予了分析。
Some pieces of amber from different origins and copal resin were tested and analyzed by FTIR and ^13C NMR. From testing results, amber from difference origins has the basically similar FTIR characteristics, such as absorption bands at 2 930, 2 870 cm^-1 caused by the saturated C-H bond stretching vibration, and the corresponding infrared absorption bands 1460-1 443 cm^-1 and 1 384-1 375 cm^-1 induced by CH2-CH3 bending vibration. Compared with the amber, FTIR characteristics of copal resin show infrared absorption weak band at 3 080 cm^-1 induced by C=CH2 antisymmetric stretching vibration, infrared absorption bands at 1 645 cm^-1 induced by C=C stretching vibration and infrared absorption band at 890 cm^-1 caused by C-H out of plane deformation vibration. Analyses of FTIR and ^13C NMR characterize amber from different origins and natural resin with relative different petrochemical maturity degree. The age of amber from Burma, Dominica, Liaoning and Mexico reduce in turn. Peaks of ^13C NMR spectrum at δ= 14× 10^-6 -18 × 10^-6 and δ= 179 × 10^-6 -220× 10^-6 only appear in copal resin, showing that the petrochemical maturity is relatively low. This paper finally concludes the FTIR and ^13C NMR spectrum characterization and significance of amber from different origins.