波罗的海、多米尼加共和国、墨西哥和缅甸琥珀的荧光光谱特征

Fluorescence Spectral Characteristic of Ambers from Baltic Sea, Dominican Republic, Mexico and Myanmar

  • 摘要: 数十百万年前的松柏科、豆科和南洋杉科植物分泌出液体树脂,其经过漫长复杂的物理化学变化和地质埋藏,逐渐成熟为物理化学性质稳定、品种多样的有机宝石——琥珀。在常规宝石学性质中,不同产地的琥珀具有特征的发光行为:在长波紫外(365 nm)灯下,波罗的海琥珀呈现黄白色荧光,多米尼加共和国和墨西哥琥珀呈现蓝色-蓝绿色荧光,缅甸琥珀的荧光常呈蓝紫色调;在短波(254 nm)紫外灯下,以上产地琥珀的荧光较长波紫外灯下的弱。为全面地探究波罗的海、多米尼加共和国、墨西哥和缅甸琥珀的荧光特征,对比分析不同产地琥珀荧光特征的差异,笔者采用JASCO FP8500荧光光谱仪采集各产地琥珀样品在220~500 nm激发波长范围内的荧光发射峰(范围为240~750 nm)。荧光激发与发射光谱结果显示,波罗的海琥珀样品的最强荧光峰位于435 nm附近,对应的最佳激发波长为350 nm;多米尼加琥珀的荧光峰成组出现,以445、474、508 nm为中心,该组荧光峰在440 nm处激发最强,415 nm次之;墨西哥琥珀样品的最强荧光峰在420~465 nm蓝紫区内变化,对应的最佳激发波长在370 nm附近;缅甸琥珀样品的最强荧光峰位于426 nm附近,其对应的最佳激发波长为375 nm。此外,缅甸琥珀样品在紫外光区还出现了一组以334,347 nm为中心的弱发射峰,其最佳激发波长为295 nm。

     

    Abstract: Amber was formed millions years ago, through various complicated physical-chemical reactions and subsequent geological process, before they deposited in current depositions. There are many well-known amber mines distributed in Baltic Sea coast region, Dominican Republic, Mexico and Myanmar. Observed under long-wave ultraviolet light (365 nm), amber from these origins present different fluorescent characteristics. In order to gain more fluorescence information and to analyze the detailed fluorescent features among samples from these four regions, we used JASCO FP8500 spectrofluorometer at room temperature, to gain their excitation spectra in 220-500 nm range and emission spectra in 240-750 nm range.The results show that Baltic amber has the strongest emission peak in blue region with the center near 435 nm, which is best excited by 350 nm light. Dominican amber emits three typical narrow peaks at 445 nm, 474 nm and 508 nm. These two samples are optimally excited by 440 nm light, following by 415 nm. The strongest fluorescence center of Mexican amber varies in 420-465 nm under 370 nm excitation. The emission centers of Myanmar appear in visible and ultraviolet region. In visible region, Myanmar has a strong 426 nm emission band, best excited by 375 nm. In ultraviolet region, Myanmar shows two weaker emission peaks near 334 nm and 347 nm optimally excited by 295 nm light.

     

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