EXAFS Study of the Local Structure for Semimetal-Semiconductor Transition in Bismuth Clusters

Abstract

Extended X-ray absorption fine structure (EXAFS) measurements were carried out in order to investigate the phase transition of bismuth clusters from semi-metallic nanocrystal to semiconducting amorphousness depending on the size. XAFS functions were Fourier-transformed and analyzed by the curve fitting method. The peaks around 3.0Å and 3.6Å are attributed to the nearest neighbors within the the layer and between the interlayer, respectively. In the 0.5 nm thick films the covalent bond length within the layer slightly shortens and the peak originated from the interlayer disappears.

Atomic Distribution and Morphology of Colloidal Particles Precursors of Bismuthinite

“…These chains interacted with each other via a weak metallic Bi−Bi bond (Figure ). The shortest atomic bond length between bismuth atoms of two neighboring chains was 0.366 nm, which was similar to the interatomic distance between layers in metallic bismuth (0.36 nm) . This interaction between chains gave rise to double layers perpendicular to the a -axis and connected via metallic Bi−Bi bonds (Figure ).…”

Photoelectron Mean Free Path on the EXAFS Analyses for Nanoparticles

“…where 2 , ω and k are loss frequency and momentum, k c is plasmon cut-off momentum, ω p is plasmon frequency for the bulk, j l is the l−th order spherical Bessel function, and ε is the static dielectric constant. In the present calculations, the relaxation time τ is calculated by use of the relation m/(ρne 2 ) where ρ is the electrical resistivity, and n is the number density of electrons [8].…”

“…Nanoparticles have intensively been studied and their applications are now widely spread in various scientific and industrial fields [1]. X-ray Absorption Fine Structure (XAFS), X-ray Photoelectron Spectroscopy (XPS) and Electron Energy Loss Spectroscopy (EELS) are unique tools for investigating local structures and electronic states of nanoparticles [2][3][4]. In these spectroscopic methods, the inelastic mean free path (IMFP) plays an important role for data analyses.…”

“…There are several examples of EXAFS analyses applied to metal nanoparticle systems [2][3][4]; They discuss the particle size dependence of the coordination number. Ikemoto et al find that the breakdown of the transferability of bulk IMFP to nanosystems.…”