琥珀是一种天然有机宝石, 普遍具有荧光现象。 利用三维荧光光谱分析技术, 以缅甸琥珀为研究对象, 探讨了不同品种缅甸琥珀的荧光峰分布特征, 并初步判断了血珀荧光峰红移的原因。 结果表明, 在长波紫外光照下呈强蓝白色荧光的缅甸金珀、 棕珀, 三维荧光光谱中均含有一个荧光峰, 荧光峰范围约在 λ_ex350~400 nm/ λ_ex400~450 nm, 荧光主峰位于 λ_ex360 nm/ λ_em425 nm, 荧光强度大。 在长波紫外光照下呈弱土黄色荧光的缅甸血珀, 三维荧光光谱中荧光峰范围约在 λ_ex420~520 nm/ λ_em500~580 nm, 荧光峰分散呈多个小峰分布, 荧光强度小。 在氧化条件下加热金珀样品得到烤色“血珀”并对比加热前后的三维荧光光谱特征, 发现烤色“血珀”的荧光峰较加热前红移, 荧光峰范围由 λ_ex350~400 nm/ λ_ex400~450 nm红移至 λ_em480~530 nm/ λ_em 520~570 nm, 荧光强度极小, 与天然血珀的荧光特征一致。 结合红外吸收光谱测试, 氧化作用使血珀及烤色“血珀”分子结构中含氧基团羰基C=O浓度升高, 羰基C=O作为强助色基团, 浓度升高与吸收强度增加使琥珀产生红色外观; 同时作为得电子取代基, 羰基C=O会取代分子结构中的H原子与具有未键合的杂原子相连, 产生 n→π1*跃迁, 使血珀荧光强度减弱甚至消失, 同时荧光峰向长波长方向移动。 三维荧光光谱能够快速有效地表征缅甸琥珀的荧光现象, 为研究琥珀荧光特征与分子结构提供新依据。

As a kind of organic gemstone, amber generally has a fluorescence phenomenon. In this paper, the three-dimensional fluorescence spectra were adopted to explore the spectral characteristics of Burmese amber, which served as the object of study. The results showed that for Burmese golden amber and brown amber, which emit glaringly bluish-white fluorescence under long-wave ultraviolet radiation, there was a fluorescence peak in the three-dimensional fluorescence spectra, the scope of the peak was about λ_ex350~400 nm/ λ_ex400~450 nm, and the main fluorescence peakwas positioned at λ_ex360 nm/ λ_em425 nm, with high fluorescence intensity. For the Burmese blood amber, which glows in earthy yellowish fluorescence under long-wave ultraviolet, its fluorescence peaks were located at about λ_ex420~520 nm/ λ_em500~580 nm, and the fluorescence peaks were scattered in multiple small peaks, with weak fluorescence intensity. Heating the golden amber and brown amber samples under oxidizing conditions produced baked “blood amber”, and it was found by comparing its three-dimensional fluorescence spectra before and after baking that fluorescence peaks of the baked “blood amber”, compared with those before baking, were red-shifted, from λ_ex480~530 nm/ λ_em520~570 nm, with extremely weak fluorescence intensity, which was consistent with the fluorescence characteristics of the natural blood amber. The infrared absorption spectrum demonstrated that oxidation caused the concentration of oxygen-containing groups such as carbonyl C=O in the molecular structure of blood amber and baked blood amber to increase. As a strong chromophore group, Carbonyl C=O made amber in a red appearance with its increased concentration and absorption intensity. Meanwhile, as an electron with drawing substituent, Carbonyl C=O replaced the H atom in the molecular structure and linked with the impurity atom with no bonding, producing n→π1* transition, making the fluorescence intensity of amber weakened, and even quenched, as well as facilitating the fluorescence peaks to shiftin the long wavelength direction. The Three-dimensional fluorescence spectra can present the fluorescence phenomena of Burmese amber in a fast and effective manner, and provides a new analysis tool for the study of amber’s fluorescence characteristics and molecular structure.