宝石级蓝方石的荧光光谱

The Fluorescence Spectra of Gem-Quality Hauyne

蓝色蓝方石,属于方钠石族矿物,是稀有的宝石品种,主要产自德国埃菲尔地区,具有特征的橙黄色荧光,文献中未见对其荧光光谱的记录。对20余颗该地区产出的蓝色蓝方石进行了宝石学基本性质的测量与观察,观察发现这批蓝方石具有不同程度的蓝色体色,橙黄色荧光仅在长波紫外光(365 nm)下可见,在短波紫外光(254 nm)下惰性。依靠荧光光谱仪对样品的光致发光现象进行定量描述可以得到一系列发射光谱。实验表明,发橙黄色荧光的样品中存在以566和425 nm为中心的荧光峰。其中565 nm的荧光可以被300~500 nm范围的入射光所激发,最佳激发波长397 nm,它决定了样品的荧光颜色;而350 nm荧光可以被260~325 nm范围内的紫外光所激发,最佳激发波长310 nm。397 nm激发下的高分辨率荧光发射光谱表明, 565 nm荧光峰上伴有大量阶梯状峰肩,中心分别是581, 600, 621, 642和666 nm,相邻两峰间能量差值约为0.07 eV。观察到荧光的强度与样品的蓝色深浅呈负相关,即蓝色越浅的样品橙色荧光越强,因此推测566 nm处荧光峰及后续肩峰与致色团S-2有关。

Blue hauyne from the Eiffel District,Germany,which belongs to sodalite group mineralogically,is among the rarest gem species.Some crystals represent characteristic orange fluorescence,but few details in its fluorescence spectra were found in the literature.In this paper,more than 20 gem-quality hauyne samples from this region were collected and tested.This batch of hauyne shows body color differing from pale grayish blue to dark blue.Orange fluorescence is only visible under long-wave ultraviolet light(365 nm),while inert under short-wave ultraviolet light(254 nm).Fluorescence spectrometer was applied to describe the photoluminescence phenomenon of samples.A series of fluorescence spectra were collected,including 3D ones.Results showed that the emission band of samples with orange fluorescence centered at 566 and 425 nm.The 566 band,which determines the fluorescence color of the sample,can be excited by light of wavelength range of 300~500 nm,and the optimal excitation wavelength is 397 nm.Furthermore,the 350 nm band can be excited by the 260~325 nm range ultraviolet light,with a best excitation wavelength of 310 nm.High-resolution emission spectrum under 397 nm showed that 566 nm band is accompanied by a large number of stepped fluorescence peak shoulder,which centers at 581,600,621,642,666 nm respectively.The energy differential of adjacent shoulders is about 0.07 eV.It was observed that the intensity of orange fluorescence was negatively correlated with the depth of blue of the samples,that is,the lighter the blue was,the stronger the orange fluorescence of the sample was.Therefore,it was speculated that the fluorescence peak at 566 nm and its subsequent acromion were related to chromophore S-2.