用双晶衍射仪作小角散射测量

MEASUREMENT OF SMALL ANGLE X-RAY SCATTERING WITH DOUBLE CRYSTAL DIFFRACTOMETER

双晶衍射仪的分辨本领高,测量范围小,最适合作小角散射测量。可是长期以来都认为它的背底较重,能掩盖小角散射的讯号而未能普遍应用。本文指出这种背底主要来自两个方面:一是第二晶体的荧光;一是晶体摆动曲线的尾部效应。前者可以用波高分析器来扣除。本文提出一种对尾部效应的扣除方法。经实测验证,这个方法是满意的。

Double crystal diffractometer applied to measure SAXS is very satisfactory, since it has high resolving power and relatively small measure area. But for a long time it has not been used widely, because it has comparatively strong background which may cover the signal of SAXS. We point out that this background results from two kinds of its sources, one is the fluorescence come from the second crystal; the other is the effect of tail part of the rocking curye of crystal used. The contribution of the first source can be subtracted by a pulse height analyser. We present here a method that can subtract the effect of the tail part of rocking curve. Experiment domonstrates that this method is satisfactory.