MAGNETIC DIPOLE ABSORPTION OF RADIATION IN SMALL CONDUCTING PARTICLES

We give a theoretical treatment of magnetic dipole absorption of elect romagnetic radiation in small conducting particles, at photon energies which are large compared to the single-particle level spacing, and sm all compared to the plasma frequency. We discuss both diffusive and ba llistic electron dynamics for particles of arbitrary shape. The conduc tivity becomes non-local when the frequency is smaller than the freque ncy omega(c) characterizing the transit of electrons from one side of the particle to the other, but in the diffusive case omega(c) plays no role in determining the absorption coefficient. In the ballistic case , the absorption coefficient is proportional to omega(2) for omega << omega(c), but is a decreasing function of w for omega >> omega(c).