印度尼西亚化石树脂的光致发光特征研究

Photoluminescence in Indonesian Fossil Resins

紫外灯下,化石树脂常见荧光现象,但其磷光现象仍有待表征与研究。将印度尼西亚产出的类似多米尼加蓝珀的化石树脂分为白色包体(PartⅠ)、暗色包体(PartⅡ)和基底(PartⅢ)三个部分,使用红外光谱确定其植物来源,借助三维荧光光谱仪表征化石树脂的光致发光现象(包括荧光和磷光),并探讨印尼化石树脂发光现象随地质过程变化的规律。红外光谱中1384,1377和1367 cm^(-1)的振动峰表征所研究的化石树脂来源于龙脑香科植物。印尼化石树脂的PartⅠ~Ⅲ中均存在3种特征荧光峰:紫外区330~380 nm、近紫外区388 nm和蓝绿光区446,474和508 nm,分别可被235,330和440 nm光有效激发;进一步推测可见光区荧光来源于两种不同的发光物质,两者在白色包体、暗色包体和基底中相对含量不同。同时,暗色包体和基底的磷光最强峰在537 nm附近和磷光寿命长达100 ms,比白色包体的430 nm磷光峰更强且衰减时间更长,贡献了印尼化石树脂的黄绿色磷光。结合前人火山活动刺激树脂的产生和还原环境促进芳构化作用的观点,推测印尼化石树脂中白色包体、暗色包体和基底的三维荧光光谱和磷光光谱可有效说明基底部分芳构化程度高于暗色包体,白色包体芳构化最低。

Generally,fossil resins emit distinct fluorescence under ultraviolet illumination.However,their phosphorescence remains to be characterized.In this paper,six Indonesian fossil resins similar to the Dominican blue amber,are further divided into three parts:white inclusions(PartⅠ),dark inclusions(PartⅡ),and basal body(PartⅢ).By the infrared spectrometer,three vibration peaks at 1384,1377,and 1367 cm^(-1) indicate that these Indonesian fossil resins were derived from the Dipterocarpaceae plant.Firstly,we investigated three-dimensional fluorescence contours from three parts in Indonesian fossil resins.The results show the emission wavelengths covering the 330~380 nm ultraviolet area(excited by 235 nm),the 388 nm(excited by 330 nm),and the 446,474 and 508 nm in the blue-green area(all excited by 440,415 and 395 nm).It suggested at least two fluorophores contributing to the visible-range fluorescence.The relative concentration of these two fluorophores varies from PartⅠto PartⅢ.Additionally,Indonesian fossil resin(copal)radiated a bright greenish-yellow phosphorescence when irradiated with a 365 nm ultraviolet light.PartⅡ&Ⅲhave a strong phosphorescence covering 460~650 nm with an emission center at 537 nm,while PartⅠis close to 430 nm.The lifetime of 537 nm emission lasts more than 100 ms,while that of 430 nm emission is about 50 ms.These luminescence differences indicate that PartⅡ&Ⅲunderwent more aromatization than PartⅠin the fossilization process.