空气环境飘尘测定中的若干问题

空气环境超微飘尘颗粒，不能用一般光学方法测定，必须用X射线小角散射测定，在这种测定中，都认为测量角度越低就越准确，本文指出太低角区的散射光是由于颗粒间的干涉造成的，若不设法消除，会使测定结果偏大，甚至是错误的，同时由于不同粒度的颗粒会散射到不同的角区，所以又想用这个方法去测粒度的分布，这种做法会产生错误的结果，所以测定时应特别注意。

Several Problems in Measuring the Floating Dust in the Environmental Air

The particle size of ultramicroscopic floating dust in the environmental air cannot be measured by the general methods.It must be measured by small angle X ray scattering, for which it is generally thought the smaller the angle,the higher the accuracy.It is pointed out in this paper that the scattering light in very small angle results from the interference among the particles and that the interference, unless eliminated,will lead to the measuring results being larger or even erroneous.At the same time, as particles of different sizes will scatter in different angles,it is hoped to apply this method to measure the particle size distribution.This paper points out that this measuring method will lead to erroneous results and shall be paid due attention to when the measuring is taken.