定量的穆斯堡尔谱学中比值C=C_a/C_b的实验测定

EXPERTMENTAL DETERMINATION OF RELATIVE INTENSITY COEFFICIENT IN ^(57)Fe M(?)SSBAUER SPECTROSCOPY

按定量穆斯堡尔谱学公式:S_a/S_b=(C_a/C_b)(N_a/N_b),若两类铁原子的浓度N_a和M_b是已知的,并通过实验测得强度S_a和S_b,即可求得它们的相对强度系数((C_a/C_b)。但实际上这种测量有很多困难。本文介绍在特殊条件下的若干测量结果。选用铁白云石,橄榄石、钙铁榴石和铁铝榴石四种矿物;它们的含铁量已知,且各自只含有一种价态的铁原子,各自的谱图中只出现一组四极矩双线。制备了混合吸收体,它们各自由上述四种矿物之中的两种组成,每种矿物对吸收体含铁量的贡献N_a和N_b是已知的,并让N_a/N_b 1。若将C_a相对于铁白云石、钙铁榴石和铁铝榴石分别改写为C_(akr),C_(add)和C_(akm),将C_b相对于橄榄石改写为C_(olv),所求得的结果是:C_(add)/C_(olv)=0.964(±0.025),C_(alm)/C_(olv)=0.874(±0.020),C_(akt)/C_(olv)=0.828(±0.015),对这些结果与矿物结构之间的关系进行了讨论。

The quantitative use of Mssbauer spectroscopy is based on the formula S_a/S_b= (C_aC_b/)·(N_a/N_b). Theoretically, if the concentrations of two types of iron atom, N_a and N_b, are known, the relative intensity coefficient (C_a/C_b) will be able to be obtained through experimental determination of the Mssbauer intensities S_a and S_b. In fact, it would often involve difficulties. In the present paper three (C_a/C_b)coefficients are obtained under the following special conditions:1. Four pure minerals, ankerite, olivine, andradite and almandite, were collected, each of which contains the only valence state of iron and gives the only quadrupole doublet in the Mssbauer spectrum.2. The iron concentrations of the minerals were precisely determined by wet chemical analysis.3. Mixture absorbers were prepared, each of which consists of two of the four above-mentioned, minerals, and the contributions N_a and N_b of the two minerals to each absorber with respect to its iron concentration (N_a+N_b) were known with N_a/N_b1.