Far-Infrared Absorption in Ultrafine Al Particles
1976; American Physical Society; Volume: 37; Issue: 10 Linguagem: Inglês
10.1103/physrevlett.37.625
ISSN1092-0145
AutoresC. G. Granqvist, R. A. Buhrman, J. Wyns, A. J. Sievers,
Tópico(s)Gold and Silver Nanoparticles Synthesis and Applications
ResumoThe first far-infrared measurements on metallic particles with diameters 10 nm are reported. The absorptivity is well approximated by ${\ensuremath{\alpha}}_{\mathrm{exp}}\ensuremath{\approx}{C}_{\mathrm{exp}}{\stackrel{\ifmmode \tilde{}\else \~{}\fi{}}{\ensuremath{\nu}}}^{2}$, where $3\stackrel{\ifmmode \tilde{}\else \~{}\fi{}}{\ensuremath{\nu}}150$ ${\mathrm{cm}}^{\ensuremath{-}1}$. The results are compared with the Gor'kov-Eliashberg (GE) theory of particles with quantized electronic levels as well as with the classical Drude theory. When a size distribution is included, ${\ensuremath{\alpha}}_{\mathrm{GE}}={C}_{\mathrm{GE}}{\stackrel{\ifmmode \tilde{}\else \~{}\fi{}}{\ensuremath{\nu}}}^{2}$ irrespective of level statistics. However, ${C}_{\mathrm{exp}}\ensuremath{\gg}{C}_{\mathrm{GE}}$ and the observed dependence on the diameter is directly contrary to predictions of the GE theory. Neither can the data be reconciled with the classical theory.
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