skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Time-Resolved X-ray Absorption Spectroscopy Methods

Abstract

No abstract prepared.

Authors:
; ; ;  [1]
  1. (Utrecht)
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
Sponsoring Org.:
USDOE
OSTI Identifier:
1008375
Resource Type:
Book
Resource Relation:
Related Information: In-situ Spectroscopy of Catalysis
Country of Publication:
United States
Language:
ENGLISH
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; ABSORPTION SPECTROSCOPY; X-RAY SPECTROSCOPY; TIME RESOLUTION

Citation Formats

Ressler, T., van Bokhoven, J.A., Knop-Gericke, G., and de Groot, F.M.F.. Time-Resolved X-ray Absorption Spectroscopy Methods. United States: N. p., 2007. Web.
Ressler, T., van Bokhoven, J.A., Knop-Gericke, G., & de Groot, F.M.F.. Time-Resolved X-ray Absorption Spectroscopy Methods. United States.
Ressler, T., van Bokhoven, J.A., Knop-Gericke, G., and de Groot, F.M.F.. Mon . "Time-Resolved X-ray Absorption Spectroscopy Methods". United States. doi:.
@article{osti_1008375,
title = {Time-Resolved X-ray Absorption Spectroscopy Methods},
author = {Ressler, T. and van Bokhoven, J.A. and Knop-Gericke, G. and de Groot, F.M.F.},
abstractNote = {No abstract prepared.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Mon Feb 12 00:00:00 EST 2007},
month = {Mon Feb 12 00:00:00 EST 2007}
}

Book:
Other availability
Please see Document Availability for additional information on obtaining the full-text document. Library patrons may search WorldCat to identify libraries that hold this book.

Save / Share:
  • The time-resolved luminescence spectra and decay kinetics of BaF{sub 2}, BGO, and CeF{sub 3}, were measured with the dissector technique using X-ray synchrotron radiation (SR) of different spectral composition from wiggler mounted at VEPP-3 storage ring (Novosibirsk). Two effects of X-ray excitation energy on the luminescence parameters were observed: modifications of the emission spectrum and acceleration of decay kinetics. Under the excitation by soil X-ray SR the 220 nm emission band for BaF{sub 2} is broadened, whereas shorter wavelength part of CeF{sub 3} and BGO emission spectra increases. For luminescence decay of excitons and chemiluminescence the degree of the deviationmore » from the single exponential law depends on the photon energies and increases under soft X-ray excitation as well. These effects are supposed to be due to the interaction of electronic excitations created after the relaxation of deep core holes. Fast intrinsic luminescence was observed for CdI{sub 2} and CsPbCl{sub 3} under X-ray SR excitation. 500 nm band of CdI{sub 2} has characteristic time {tau} = 4.6 ns, whereas 420 nm band of CsPbCl{sub 3} shows very fast decay with {tau} = 0.2 ns.« less
  • Desulfation by hydrogen of pre-sulfated Pt(2wt%) BaO(20wt%)/Al2O3 with various sulfur loading (S/Ba = 0.12, 0.31 and 0.62) were investigated by combining H2 temperature programmed reaction (TPRX), x-ray photoelectron spectroscopy (XPS), in-situ sulfur K-edge x-ray absorption near-edge spectroscopy (XANES), and synchrotron time-resolved x-ray diffraction (TR-XRD) techniques. We find that the amount of H2S desorbed during the desulfation in the H2 TPRX experiments is not proportional to the amount of initial sulfur loading. The results of both in-situ sulfur K-edge XANES and TR-XRD show that at low sulfur loadings, sulfates were transformed to a BaS phase and remained in the catalyst, rathermore » than being removed as H2S. On the other hand, when the deposited sulfur level exceeded a certain threshold (at least S/Ba = 0.31) sulfates were reduced to form H2S, and the relative amount of the residual sulfide species in the catalyst was much less than at low sulfur loading. Unlike samples with high sulfur loading (e.g., S/Ba = 0.62), H2O did not promote the desulfation for the sample with S/Ba of 0.12, implying that the formed BaS species originating from the reduction of sulfates at low sulfur loading are more stable to hydrolysis. The results of this combined spectroscopy investigation provide clear evidence to show that sulfates at low sulfur loadings are less likely to be removed as H2S and have a greater tendency to be transformed to BaS on the material, leading to the conclusion that desulfation behavior of Pt BaO/Al2O3 lean NOx trap catalysts is markedly dependent on the sulfation levels.« less
  • Desulfation by hydrogen of presulfated Pt (2 wt %)-BaO(20 wt %)/Al{sub 2}O{sub 3} with various sulfur loading (S/Ba = 0.12, 0.31, and 0.62) were investigated by combining H{sub 2} temperature programmed reaction (TPRX), X-ray photoelectron spectroscopy (XPS), in situ sulfur K-edge X-ray absorption near-edge spectroscopy (XANES), and synchrotron time-resolved X-ray diffraction (TR-XRD) techniques. We find that the amount of H{sub 2}S desorbed during the desulfation in the H{sub 2} TPRX experiments is not proportional to the amount of initial sulfur loading. The results of both in situ sulfur K-edge XANES and TR-XRD show that at low sulfur loadings, sulfates weremore » transformed to a BaS phase and remained in the catalyst rather than being removed as H{sub 2}S. On the other hand, when the deposited sulfur level exceeded a certain threshold (at least S/Ba = 0.31) sulfates were reduced to form H{sub 2}S, and the relative amount of the residual sulfide species in the catalyst was much less than at low sulfur loading. Unlike samples with high sulfur loading (e.g., S/Ba = 0.62), H{sub 2}O did not promote the desulfation for the sample with S/Ba of 0.12, implying that the formed BaS species originating from the reduction of sulfates at low sulfur loading are more stable to hydrolysis. The results of this combined spectroscopy investigation provide clear evidence to show that sulfates at low sulfur loadings are less likely to be removed as H{sub 2}S and have a greater tendency to be transformed to BaS on the material, leading to the conclusion that desulfation behavior of Pt-BaO/Al{sub 2}O{sub 3} lean NO{sub x} trap catalysts is markedly dependent on the sulfation levels.« less
  • The electronic structure of thin film wurtzite GaN has been studied using a combination of angle resolved photoemission, soft x-ray absorption and soft x-ray emission spectroscopies. The authors have measured the bulk valence and conduction band partial density of states by recording Ga L and N K- x-ray emission and absorption spectra. They compare the x-ray spectra to a recent ab initio calculation and find good overall agreement. The x-ray emission spectra reveal that the top of the valence band is dominated by N 2p states, while the x-ray absorption spectra show the bottom of the conduction band as amore » mixture of Ga 4s and N 2p states, again in good agreement with theory. However, due to strong dipole selection rules the authors can also identify weak hybridization between Ga 4s- and N 2p-states in the valence band. Furthermore, a component to the N K-emission appears at approximately 19.5 eV below the valence band maximum and can be identified as due to hybridization between N 2p and Ga 3d states. They report preliminary results of a study of the full dispersion of the bulk valence band states along high symmetry directions of the bulk Brillouin zone as measured using angle resolved photoemission. Finally, they tentatively identify a non-dispersive state at the top of the valence band in parts of the Brillouin zone as a surface state.« less