穆斯堡尔谱学中样品最佳厚度的确定

DETERMINATION OF THE OPTIMUM THICKNESEOF AN ABSORBER IN MOSSBAUER SPECTROSCOPY

提出一种理论计算结合实验测量来确定穆斯堡尔（Ｍｏｓｓｂａｕｅｒ）谱实验样品最佳厚度（ｄｏｐｔ）的办法。在穆斯堡尔谱测量中，信噪比（Ｑ）可用一个解析式来表示，其值随实验样品厚度的变化有一个极大值，它对应于样品的最佳厚度ｄｏｐｔ．研究表明，要确定一个样品的最佳厚度ｄｏｐｔ，除了清楚其化学成分外，若准确知道样品的无反冲分数ｆａ，则可以直接通过理论计算来求ｄｏｐｔ；否则，就要用本文介绍的办法来确定ｄｏｐｔ。

Here is presented a method for calculating the optimum thickness dopt of an absorber in combination with the Mossbauer measurements. It is convenient to define a sig- nal-to-noise ratio (S/N) ,as a function expression of the absorber thickness ,this ratio reach- es a maximum value at optimum thickness dopt, corresponding the maximum Mosslsauer ef- fect and smaller statistical error. In the case of lacking the knowledge of recoilless fraction fa for a giren material ,a series of Mossbauer spectra with different absorber thickness must be carried out , and a fit Of the experiment data to the S/N ratio yields dopt . Our investigation shows that the S/N ratio excellently describe the experiment results ,so if fa is known accu- rarely .one can calculate dopt by using the S/N ratio without measurement process.