Study of Mie extinction efficiency

This Paper analyzes the mathematical character of the extinction efficiency (normalized extinction cross section) and studies the numerical computation of it. The paper discusses the relations of the extinction efficiency and the size parameter x and the relations of the peak value of the ripple structure of the extinction efficiency and the amplitude of Mie scattering an(x, m), bn(x, m). The paper also discusses the relations of the approximate periodicity of the ripple structure and relative refractive indices m. The result shows that relation curve of the extinction efficiency and the size parameter x has ripple structure, which become faint as x is large; when the relative indices m is real and m<=2, the ripple structure has single periodicity, and positions of the peak values of the ripple structure are corresponding to the positions of peak values of Re[an(x, m)]and Re[bn(x, m)]. When m is complex and Im(m)<0.01, the ripple structure also has the same periodicity, however, the oscillation amplitude of the ripple structure becomes weaker. The larger Im(m) is, the weaker the oscillation amplitude of the ripple structure is.