天然钻石与合成钻石的特异性光谱初步研究

Preliminary Study on the Unique Spectroscopic Characteristics of Natural and Synthetic Diamonds

通过紫外-可见-近红外（UV-Vis-NIR）吸收光谱、傅里叶变换红外（FTIR）光谱及钻石观测仪（DiamondViewTM）对天然钻石、经辐照或热处理的天然钻石、高温高压（HTHP）合成钻石及化学气相沉积（CVD）合成钻石进行了较系统的谱图及微区生长结构的对比研究。结果表明：天然钻石、经辐照或高温退火处理后的天然钻石、高温高压（HTHP）合成钻石的UV-Vis-NIR吸收谱图在200~1 100nm区间谱图的反射率变化明显。相比之下,CVD合成钻石的反射率的变化相对较小。基于钻石样品的红外光谱分析,在其图谱中的800~1 600cm^-1区间,合成钻石样品、特别是CVD合成钻石在上述区间无明显的特征吸收峰位。此外,DiamondViewTM检测表明：一般而言,经HTHP处理后的CVD合成钻石出现平行的位错线,并呈现淡蓝色荧光。部分天然钻石可见典型的八面体生长线或称为树的年轮状图像,且因样品经辐照与高温高压处理后其荧光图像的颜色发生改变。高温高压合成钻石呈现出块状几何生长图像。限于钻石样品类别的多样性及合成钻石工艺的复杂且不断更新特征,天然钻石与合成钻石的UV-Vis-NIR或FTIR光谱特征存在一定的相似性,因此不具有典型天然钻石图谱特征的样品需进一步辅以DiamondViewTM、光致发光光谱等其他检测仪器予以综合分析。

A systematic comparative study on the natural diamond ,the natural diamond treated by heat or irradiation and syn‐thetic diamond prepared by chemical vapor deposition （CVD） or High temperature and high pressure （HTHP） were carried out by UV‐Vis‐NIR absorption and FTIR spectra .The results showed that ：natural diamond ,treated natural samples such as irradi‐ated or annealed ones under high temperature and the HT HP synthetic diamond ,the reflection coefficient is obviously variation between 200 nm and 1100 nm in UV‐Vis‐NIR spectra of above samples .In contrast ,the reflection coefficient of CVD synthetic diamond is relatively smaller than the former .Infrared spectra showed that synthetic diamonds ,especially for CVD synthetic dia‐monds have no obvious absorption peak between 800 and 1 600 cm^-1 .In additional ,the results of DiamondView^TM detection are different for different kinds of diamonds .Generally speaking ,some CVD synthetic diamonds treated by HTHP appears some parallel dislocation lines ,and show light‐blue fluorescence .HPHT synthetic diamonds exhibit strong blocky geometrical shapes whereas some natural diamonds exhibit more tree‐ring type fluorescence patterns ,the color of diamonds’ fluorescence image may change after treated by HT HP or irradiation .In a word ,in view of the diversity and innovation of the synthesis technologies for diamond ,the natural and synthetic diamonds have some similar spectra characteristic in term of UV‐Vis‐NIR and FTIR spectra , some special natural diamonds without typical spectra characteristic of natural ones need to be further supplemented with Dia‐mondView^TM ,photoluminescence spectra and other instruments .