Photoelectron Mean Free Path on the EXAFS Analyses for Nanoparticles

Miyanaga, Takafumi; Nakamae, Manabu; Nago, Harutaka; Ohori, Yusuke; Fujikawa, Takashi

doi:10.1380/ejssnt.2012.565

Cited by 5 publications

(3 citation statements)

References 10 publications

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“…While for n S , the trend of the experimental results agrees well with that of the calculated results, and the experimental values of n B are slightly smaller than the calculated values. In general, the coordination number appears smaller than it is . This trend is true in our results, as shown in Figure a.…”

Section: Resultssupporting

confidence: 79%

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Microscopic Structure of Naked Au Nanoparticles Synthesized in Typical Ionic Liquids by Sputter Deposition

et al. 2014

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Au nanoparticles (AuNPs) of varied sizes were synthesized in typical ionic liquids using the sputter deposition technique. Because AuNPs are dispersed freely in each ionic liquid without bonding to particular stabilizing agents, they are sometimes called “naked AuNPs”. To characterize the structure of naked AuNPs, we obtained a size distribution curve from small-angle X-ray scattering (SAXS) experiments and extracted the value of the peak position as the size of the most abundant AuNPs in each ionic liquid. The size was controlled by the type of ionic liquid and preparation temperature. To elucidate the local structure of the AuNPs in relation to their particle size, we measured the X-ray absorption fine structures (XAFS) at the Au L3-edges. The analyses of the extended XAFS revealed that the Au–Au bond lengths for AuNPs ∼1 nm in size are 2.76 to 2.81 Å, in contrast with the 2.88 Å bond lengths for bulk Au. Comparing our SAXS and XAFS results with previously reported theoretical studies, we conclude that the surface Au atoms of the naked AuNPs in ionic liquids have shorter bond lengths than the inner atoms.

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Section: Resultssupporting

confidence: 79%

“…In general, the coordination number appears smaller than it is. 61 This trend is true in our results, as shown in Figure 3a. Moreover, the difference may be caused by the assumption of only two bonding length types, where the type of bonding between a surface atom and an inside atom is included in n B in the calculation.…”

Section: Saxs Analysismentioning

confidence: 99%

Microscopic Structure of Naked Au Nanoparticles Synthesized in Typical Ionic Liquids by Sputter Deposition

et al. 2014

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“…Plasmon produced by collective electron excitation influenced by electrical state of materials is studied in order to evaluate its mean free path and escape depth [1,2]. Core-level X-ray photoemission spectra (XPS) have clear plasmon loss bands in low energy side in addition to the main sharp band for simple metals and semiconductors.…”

Section: Introductionmentioning

confidence: 99%

Azimuthal Angular Dependence of Plasmon Loss in Core-Level Photoemission with Multiple Scattering Theory

Yamamura

Tamura

Kazama

et al. 2016

e-J. Surf. Sci. Nanotech.

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We have theoretically studied the azimuthal angular dependance of surface and bulk plasmon losses in Al 2s photoemission spectra. Here, full multiple scatterings of photoelectrons are taken into account before and after plasmon losses within the quantum Landau formula, which can describe overall features of the photoemission bands. By considering elastic scattering, the azimuthal angular dependence can be evaluated. Two types of peaks are observed; strong peaks attributed to forward focusing and weak peaks appeared as diffraction pattern. Forward focusing peaks are observed when atoms exists in the forward direction. The peak intensities from deeper layers are reduced by the defocusing effect. The origin of the weak peaks are discussed with the local geometric analysis. The differences of main, 1st bulk and surface plasmon loss are discussed.The peaks of diffraction pattern largely changed by increasing the photoelectron kinetic energy.

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