蓝宝石的光学吸收谱研究

对蓝宝石光学吸收谱10个吸收带的特征作了详细讨论,结果表明,在所有不同颜色的蓝宝石样品中和在每个样品的不同偏振方向上,由光谱拟合求得的各带的峰位和带宽都基本不变,差别仅表现在带的强度上。通过聚类分析,这些带被分为5类,分别被命名为a,b,c,d和e,对它们的指派结果是:a带(a_1,a_2和a_3)为Fe~(3+)的自旋禁戒d-d跃迁;b带(b_1和b_2)和c带分别为Fe~(2+)/Ti~3+)交换耦合对和Fe~(2+)/Fe~(3+)交换耦合对跃迁;d带(d_1和d_2)为Ti~(3+)的自旋允许d-d跃迁;e带(e_1和e_2)则为Fe~(2+)的自旋禁戒d-d跃迁。

OPTICAL ABSORPTION SPECTRA OF SAPPHIRE

The optical absorption spectrum of sapphire consists of ten bands. Their characteristics are discussed. As a result, the peak position and width (both in cm~(-1)) of a band obtained by spectrum fitting is almost the same in all samples with different colors or in different polaried directions in a sample. The difference only appears in the band intensity. By cluster analysis, all the ten bands are grouped under five heads named respectly a,b,c,d and e. As a conclusion of this paper, the assignment of bands is discussed. Band-a (including three single band: a_1, a_2, and a_3) is assigned to the spin-forbiden d-d transition of Fe~(3+); band-b (b_1 and b_2) and band-c to the exchanged coupled Fe~(2+)-Ti~(3+) and Fe~(2+)-Fe~(3+) pairs respectly ;band-d (d_1 and d_2) to the spin-allowed d-d transition of Ti~(3+), and band-e (e_1 and e_2) to the spin-forbiden d-d transition of Fe~(2+).