在溴化钾粉末中掺入大量α-炭化硅压片的异常红外透射光谱研究

Study of Unusual Infrared Transmittance Spectrum of the KBr Pellet with a Large Amount of α-SiC Powders

在光谱学实践中 ,通常由于带测样品颗粒在本征吸收峰附近产生可观的附加散射消光 ,致使表观吸收峰偏离实际位置 ,从而得到不准确的光谱 ,这就是我们常要采取措施尽量避免的克里斯坦森 (Christiansen)效应。措施之一就是在制作压片 (例如溴化钾 )时 ,待测样品含量要少 (少于 2 % )。在一次实验中 ,当在KBr粉末中掺入大量 (而非正常要求的少许 )的α SiC微粉后 ,得到了一个在 10 5 2 33cm-1处有一个尖峰的中红外透射谱。我们发现 ,这个新现象非常有趣 ,它与克里斯坦森效应表面上相反 ,但都可用Lorentz色散模型给予精确地解释 ,于是称它为反克里斯坦森效应 ,在该效应出现的频率处两种材料的折射率相等 ,且吸收系数都非常小。这个新现象也非常有意义 。

In the spectroscopic experiments,additionally large extinction caused by the scattering in the vicinity of inherent absorption peaks of the measured sample granules can lead to a deviation of measured absorption peak from the corresponding inherent one,then an incorrect spectrum appears.This is just the Christiansen effect that we must take cares to avoid as much as possible.One of the measures we take is to use a small amount of sample material (less than 2%) when we make the pellets,for example KBr is the matrix.In an experiment,when a large (not small as usual) amount of α-SiC powder is dispersed into KBr powder, the resulted pellet has an infrared transmission spectrum with a sharp peak at the position of 1 052.33 cm -1.We find that this new phenomenon is very interesting, and looks contrary to the usual Christiansen effect, but can be explained with Lorentz dispersion model accurately together, so we call it reverse-Christiansen effect.Exactly at this frequency,the refractive indices of these two materials are equal,and absorption coefficients are very small. Also, it is very useful for making a new type of band-pass filter or determining the refractive indices of some materials correctly, etc.