the surface and volume modes of a dielectric sphere.

Thus a substantial part of the sphere modes (about one half) belong to the interior surface modes. It is important that respective frequencies are the [*first*]{} roots of the characteristic equations.

In order to escape the confusion, it is worth noting here that the surface modes in the problem in question obey the same boundary conditions at the sphere surface and when $r\to \infty$ as the volume modes do. Hence, these surface modes cannot be classified as the evanescent surface waves propagating along the interface between two media (propagating waves along dielectric waveguides [@Jackson], surface plasmon waves on the interface between metal bulk and adjacent vacuum [@Raether; @BPN] and so on). When describing the evanescent waves one imposes the requirement of their exponential decaying away from interface between two media. In this respect the evanescent surface wave differ from the modes in the bulk.

Implication of QNM of a dielectric sphere for estimation of the health hazard of portable telephones
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Here we shall argue that the features of the quasi-normal modes of a dielectric sphere (namely, existence of surface and volume modes) should be taken into account, in particular, when 