链状硅酸盐矿物中^(57)Fe同质异能移和二级多普勒移

ISOMER SHIFTS AND SECOND-ORDER DOPPLER SHIFTS OF ^(57)Fe IN CHAIN SILICATES

以德拜特性温度为可调参量 ,用德拜理论近似分析了某些链状硅酸盐矿物在不同温度、压力下的 57Fe中心移 (δCS)数据。二级多普勒移 δSOD用德拜理论估计 ,并由 δCS的实验值与 δSOD的估计值之差获得同质异能移 δIS。结果表明 ,对中心移的主要贡献来自同质异能移 ,在室温下 ,二级多普勒移仅为中心移的 16 %。室温下 δSOD的压力系数比 δIS的小一个数量级以上 ,故压力改变时δCS的变化主要是δIS的变化引起的。反之 ,在常压下改变温度 ,δCS的变化主要由δSOD的变化决定 ,δIS随温度的变化比 δSOD要小得多。

Temperature and pressure dependent center shift ( δ CS ) data of 57 Fe in some chain silicates were analyzed to Debye approximation using the Debye characteristic temperature as an adjustable parameter. The second order Doppler shifts, δ SOD , were estimated in terms of the Debye theory and the isomer shifts, δ IS , were obtained as the differences between the experimentally determined δ CS and the estimated values of δ SOD . It has been found that the main contribution to δ CS comes from δ IS . At room temperature only about 16 percent of the observed center shift is of vibrational nature. The pressure coefficient of δ SOD is found to be more than one order of magnitude less than that of δ IS . Therefore, the pressure variation of δ CS is mainly due to the change in δ IS . At ambient pressure the temperature variation of δ CS , for the most part, comes from that of δ SOD .