以两种典型的气溶胶粒子组成的单分散和多分散外混合气溶胶粒子系统的光散射的各效率因子、各散射截面和散射相函数分析了以等效折射率描述由具有不同折射率的各种粒子组成的混合气溶胶粒子系统的适用性。结果表明，对单分散系统，在不同的混合比下对于许多尺度参数吸收效率因子和散射相函数的等效性很差；对多分散系统，在不同的混合比下等效性较稳但各散射光学量的余差很大。因而对多分散系外混合气溶胶粒子系统如使用等效折射率，则由光散射技术测定的谱分布与实际谱分布有很大的出入。故以光散射技术研究气溶胶时，应同时采用其他手段获取粒子系统的混合信息。

The validity of the equivalent refractive index for describing the external mixture of atmospheric aerosol particles was analyzed by scattering efficiencies, cross sections, and phase functions of monodispersions and polydispersions of the external mixture of two typical aerosol particles with their complex refractive indices of very high and very low imaginary parts. Results show that for monodispersions, the equivalence for the absorption efficiency and phase functions is poor; for polydispersions, the equivalence is stable but with quite large residuals. The retrieved size distribution will have a large bias if the equivalent refractive index is employed in light scattering techniques. It was recommended to use light scattering techniques simultaneously with other techniques to monitor the mixture property of aerosol particles.