缅甸琥珀的特殊光学效应

Special Optical Effect of Amber from Myanmar

  • 摘要: 缅甸琥珀是各产地琥珀中形成年代最古老、经历地质作用时间最长、形成过程最复杂的琥珀,其种类繁多,有许多特殊的光学效应现象,如“机油光”现象、“留光”现象等。这些特殊光学效应尚未有科学系统的研究。本文以荧光光谱和磷光时间光谱为测试手段,探讨了缅甸琥珀光学效应的机制,得到了一系列新结论:(1)缅甸琥珀的荧光光谱具有良好的统一性,都具有432 nm和470 nm处的发光中心,并使得缅甸琥珀在长波紫外光下呈现紫蓝色;(2)具有“机油光”现象的红茶珀和绿茶珀都具有625~650 nm双峰发光中心,茶珀表面带红色调的“机油光”是由该发光中心的红色荧光所致。同时,红茶珀在长紫外光下呈现出的品红色荧光,也是由红茶珀同时具有蓝色荧光和红色荧光叠加形成的;(3)表面具有“绿膜”效应的“变色龙”琥珀,具有437 nm和470 nm处的紫蓝色、蓝色的强发光中心,“变色龙”表面呈现出暗绿色的“膜”是发光中心与较深的棕褐色体色叠加产生;(4)缅甸琥珀中“留光”现象的本质是磷光,其中发射波长为432 nm的磷光寿命在0.32~0.48 s范围内;发射波长470 nm的磷光寿命在0.31~0.42 s之间;发射波长650 nm的磷光寿命在0.21~0.25 s范围内;(5)不同发光中心琥珀的发光行为不同,可能为同一物质在不同波长激发下呈现的不同发光行为,也可能是琥珀中两种或两种以上的荧光物质对发光行为的贡献率随波长变化而变化。

     

    Abstract: Amber from Myanmar is the oldest amber of all origins, which has experienced the longest geological process and the most complex formation process. There are many kinds of special optical effects of amber from Myanmar, such as "oil gloss" phenomenon and "retaining light" phenomenon. Those special optical effects have not yet been studied scientifically and systematically so far. In this paper, fluorescence spectrophotometer and transient phosphorescence time-resolved spectroscopy were used to measure amber from Myanmar with special optical effects. The following conclusions are obtained: (1) The fluorescence spectra of amber from Myanmar have good uniformity, and have 432 nm and 470 nm fluorescence centers, which caused bluish violet fluorescence when exposed to ultraviolet; (2) Both black-tea amber and green-tea amber with the phenomenon of "oil gloss" have 625-650 nm bimodal luminescence centers, and the pink fluorescence on its surface is caused by the red fluorescence of the luminescence centers. At the same time, the pinkish red fluorescence of black-tea amber under long-ultraviolet light is also formed by the superposition of blue fluorescence and red fluorescence of black-tea amber powders; (3) The "chameleon" amber with "green film" effect on its surface has strong blue and purple luminescence centers at 437 nm and 470 nm, and the surface of "chameleon" shows dark green. This "green film" is the superposition of the luminous center and the deeper brown body colour; (4) The essence of the "retaining light" phenomenon in amber from Myanmar is phosphorescence, in which the lifetime of phosphorescence at 432 nm is between 0.32 s and 0.48 s; the lifetime of phosphorescence at 470 nm is between 0.31 s and 0.42 s; the lifetime of phosphorescence at 650 nm is between 0.21 s and 0.25 s; (5) The luminescence behavior of amber with different luminescence centers is different, which may be caused by different wavelength excitation, or the contribution rate of two or more fluorescent substances to the luminescent behavior of amber varying with the wavelength excitation.

     

/

返回文章
返回