Br K-Edge X-ray Absorption Near Edge Structure Analyses of Bromine Residue Carbon Compounds Using Full Multiple-Scattering Theory

Abstract

A recent experimental result shows that Br K-edge X-ray absorption near edge structure (XANES) spectra for bromine residue compounds are sensitive to the heat treatment of host carbon compounds. In the present study we attempt to extract useful information on the geometric and electronic structures of these systems by applying a full multiple-scattering approach to XANES analyses. The residue compounds can be classified into three groups on the basis of XANES spectral features. Present detailed analyses provide us some useful information: Group 1, bromine residue compounds are prepared from host carbon compounds heat-treated at 2000–2800°C, where Br2 molecules exist in the interlayer space of graphite. The interlayer distance expands to about 7.8 Å around the Br2 molecules. For heat treatment at 1900°C, the observed spectra are well explained by the superposition of the spectrum for Group 1 and that for Group 2, with a ratio of 3:4. For Group 2 heat-treated at 1500–1750°C, the host carbon compounds includes Br- ions, but no information on the Br-–C correlation has been obtained. For Group 3 heat-treated at 1000°C, the host carbon compounds mainly includes HBr molecules parallel to small aromatic carbon molecules.

A solvent-free solid catalyst for the selective and color-indicating ambient-air removal of sulfur mustard

“…Further evidence to support the catalytic nature of this material in neat agent/simulant was obtained using bromine X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) spectroscopies. The bromine K-edge XANES shows that throughout the course of the reaction, the initial Br 3 − (characterized by a 1s-4p pre-edge peak at 13,473 eV) [44][45][46] is consumed upon exposure to CEES and then reforms upon reaction completion (Fig. 3) similar to what was observed for the studies done in acetonitrile.…”

Structure and Bonding of Trace Ni Catalyst in Carbon Nanotube Studied by Ni K-Edge XANES

“…XANES spectra provide longer range information (typically ≈5Å) than EXAFS spectra, and stereochemical information. [5,6] EXAFS analyses are rather easy compared with XANES analyses. The XANES, however, has an important advantage over the EXAFS: Even weak electron scatterers carbon still provides useful information in the XANES analyses.…”

“…The XANES, however, has an important advantage over the EXAFS: Even weak electron scatterers carbon still provides useful information in the XANES analyses. [6] Main purpose of this paper is to obtain some useful information on the local structure and bonding of trace Ni species in carbon nanotube by full multiple scattering XANES analyses [7][8][9][10][11] and ab initio molecular orbital theory. The molecular orbital theory gives us some useful information about the electronic structure and the optimized structure of a Ni atom trapped at a crack-like defect site of the graphene sheet.…”

Direct Spectroscopic Observation of the Hole Polaron in Lead Halide Perovskites

“…From the GS XA spectra in Figure 2a (red) and Figure 2b (blue), we can see that there is an intense edge transition peak at 13.4731 keV, which originates from the allowed dipole electronic transition from the Br 1s orbital to the p continuum (called X-ray absorption white line). 40,41 The scattering oscillation peak (13.4864 keV) above the edge is attributed to the scattering of the photoelectron by neighboring atoms of the probed Br atoms, directly reflecting the local geometric lattice structure around the Br sites. 40,41 Because the XTA spectra were obtained as the difference of XA spectra with and without laser excitation, they can directly deliver the transient electronic and structural change information after photoexcitation.…”

“…40,41 The scattering oscillation peak (13.4864 keV) above the edge is attributed to the scattering of the photoelectron by neighboring atoms of the probed Br atoms, directly reflecting the local geometric lattice structure around the Br sites. 40,41 Because the XTA spectra were obtained as the difference of XA spectra with and without laser excitation, they can directly deliver the transient electronic and structural change information after photoexcitation. In both panels a and b of Figure 2 (turquoise), a sharp positive differential absorption peak (a) is apparent in the XTA spectra centered around 13.4673 keV, arising from a new X-ray absorption transition from the Br inner 1s orbital to the 4p orbital in VB, where the hole is photocreated by elevating the electron to the CB (Figure 1a,b).…”