New calculation of surface wave contributions associated with mie backscattering.

Diffracted field contributions to backscattering of an electromagnetic plane wave by a spherical particle are calculated. The diffracted fields give rise to surface waves in the shadow region and can be evaluated by finding surface wave poles and computing their residues. In order to compute the residues the valid range of the Schobe and Debye asymptotic expansion formulas for the Hankel function is examined. With these asymptotic formulas numerical values of the surface wave complex poles are tabulated. Curves for backscattering cross section due to the first six surface waves are presented as a function of the size parameter kappaa between 5 and 60 for absorbing spheres of refractive index m = 1.61-i0.0025 as well as nonabsorbing spheres with m = 1.60.