C. F. Bohren, "How can a particle absorb more than the light incident
on it?", Am J Phys, 51 #4, pp323 Apr 1983
A particle can indeed absorb more than the light incident on it.
Metallic particles at ultraviolet frequencies are one class of such
particles, and insulating particles at infrared frequencies are another.
In the former, strong absorption is associated with excitation of
surfaces plasmons; in the latter it is associated with excitation of
surface phonons. In both instances, the target area a particle presents
to incident light can be much greater than its geometrical
cross-sectional area. This is strikingly evident from the field lines
of the Poynting vector in the vicinity of a small sphere illuminated by
a plane wave.
H. Paul and R. Fischer "Light Absorption by a dipole", SOV. PHYS. USP.,
26(10) Oct. 1983 pp 923-926
In semiclassical radiation theory, the electric dipole moment induced
on an atom by a strong incident field absorbs much more energy, per sec,
than is flowing through its geometrical cross section. This means that
the atom has the capability to "suck up" electromagnetic energy from a
spatial region that is by far larger than its own volume. An intuitive
understanding of this effect is provided by studying, in the framework
of classical electrodynamics, the energy flow in the total field made up
by superposition of the incident wave and the field that is generated by
the dipole also in the absorptive case.
Also suggested by A. Boswell, regarding small-antenna physics:
Chu, J.Appl.Phys. Dec. 1948
Hansen, Proc.IEEE Feb. 1981
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