Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Possible Origin of the Anomalous Far-infrared Absorption by Small Metal
  Particles   We have carried out the far-infrared transmission measurements on the ligand
stabilized Au55 particles dispersed in CsI. We have found that there exists the
crossover energy Ec ~ 160 cm -1 (~ 19 meV) beyond which the absorption
coefficient recovers the classical electric dipole-like absorption and, hence,
the absorption for frequencies higher than Ec is insensitive to the particle
size. We propose that the physical origin of the enigmatic anomalous far-IR
absorption by small metal particles lies in the absorption arising from the
transitions the electrons between the discrete energy levels below Ec on which
the particle size independent, classical electric dipole absorption develops
for frequencies higher than Ec.

12
The categories of this paper are: nucl-th
9
The categories of this paper are: nlin
6
The categories of this paper are: astro-ph
29
The categories of this paper are: funct-an
22
The categories of this paper are: chao-dyn
32
The categories of this paper are: atom-ph
37
The categories of this paper are: supr-con
0
The categories of this paper are: hep-ph
33
The categories of this paper are: plasm-ph
8
The categories of this paper are: hep-ex
2
The categories of this paper are: math
36
The categories of this paper are: cmp-lg
31
The categories of this paper are: ao-sci
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The categories of this paper are: adap-org
14
The categories of this paper are: math-ph
30
The categories of this paper are: q-alg