Optical absorption of continuous films and particles of Fe and Cr: localization of conduction electrons

Tanimoto

1999

Phys. Rev. B

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E. Anno ; M. Tanimoto, Physical Review B, 60(7), 5009-5015, 1999. "Copyright 1999 by the American Physical Society."http://prola.aps.org/abstract/PRB/v60/i7/p5009_1 publisherOptical absorption of continuous-network-structure (CNS) Ag and Ir films has been measured in the photonenergy range of 0.5-6.5 eV. As absorption due to conduction electrons, optical plasma-resonance absorption (OPRA), reported for Ag island films consisting of Ag particles, and weak Drude-type absorption (DTA) were found for the CNS Ag films, and only the weak DTA appeared in the CNS Ir films. The finding of the OPRA indicates that particlelike regions, where plasma oscillations of conduction electrons occur as in Ag particles, are present in the CNS Ag films. When the particlelike regions are formed, the region, where DTA occurs, is reduced. This reduction results in the weakening of the DTA. Thus the weak DTA supports the presence of the particlelike regions. If particlelike regions are present in the CNS Ir films also, conduction-electron localization as in Ir particles should occur in the particlelike regions. In this case, only the DTA, weak as in the CNS Ag films, must appear. This agrees with the above appearance. Thus conduction-electron-localized regions are present in the CNS Ir films

Section: B Conduction-electron-localized Regions In Cns Ir Filmsmentioning

confidence: 99%

Optical absorption of continuous-network-structure Ag and Ir films: Presence of particlelike and conduction-electron-localized regions

Tanimoto

1999

Phys. Rev. B

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“…The reason may be that the OPRA is present in the energy range higher than that in this study, or that the OPRA does not occur because of the conductionelectron localization due to the strong d character as in Fe and Cr. 9 Figures 3͑a͒, 3͑b͒, and 3͑c͒ show the transmittance spectrum and its derivative of the island film with particle diameters of about 180, 120, and 70 Å, respectively. In Fig.…”

Section: A Spectra Of Continuous Thin Ru Films and Ru Island Films Wmentioning

confidence: 99%

Interband absorption of Ru studied by optical absorption of continuous thin films and small particles

Yamaguchi

1997

Phys. Rev. B

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E. Anno ; T. Yamaguchi, Physical Review B, 55(7), 4783-4786, 1997. "Copyright 1997 by the American Physical Society."http://prola.aps.org/abstract/PRB/v55/i7/p4783_1 publisherFor continuous thin Ru films and Ru island films consisting of Ru particles smaller than about 320A in diameter, optical absorption has been measured in the photon energy range of 0.5-6.5 eV. Absorption, found below about 1 eV and at about 2, 3, 3.6, and 4.5-5 eV for the continuous thin films, shifted to higher energies and became weaker with decreasing particle size. This change is accompanied by lattice contraction and is similar to the lattice-contraction-induced change in interband absorption of hcp Co. Thus, the absorption is interband absorption as for hcp Co, and is due to transitions from d states into empty states above the Fermi level. The absorption at about 2, 3, and 3.6 eV shifted almost equally (0.2-0.3 eV) and disappeared at almost the same time below about 70A in diameter, indicating that d states are close to each other. The absorption at about 4.5?5 eV was still well defined at about 25A in diameter. Cu, Ni, and Pd particles have also shown such well-defined interband absorption. Thus, as for Cu, Ni, and Pd, d states are presumably in flat or parallel bands

Optical absorption of transition-metal island films: Correlation interaction between conduction electrons of transition metals

Journal of Applied Physics

Tanimoto

2000

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Optical plasma-resonance absorption of Pt island films consisting of Pt particles larger than about 25 Å in diameter has been measured in the photon energy range of 0.5-6.5 eV. As in Rh and Pd island films reported previously, the broadening of the optical plasma-resonance absorption reflects a correlation interaction between conduction electrons. Comparison of the broadening for the Pt island films with that for the Rh island films shows that the correlation interaction is strong when the conduction-electron density n is low. In an electron-gas model, the correlation interaction between electrons becomes stronger with lowering electron density, because the magnitude ratio of the Coulomb to kinetic energy increases as the electron density lowers. Thus, the strong correlation-interaction at low n proves that the correlation interaction in transition metals becomes stronger with magnitude ratio. The magnitude ratio in transition metals is pointed out to increase with lowering n and/or with strengthening d character of conduction electrons. Based on the correlation interaction, reflected by the broadening for the Pt, Rh, and Pd island films, and on the strong correlation interaction, found previously for Ir, the order of magnitude ratio is IrϾPtϾPdϾRh.