Energy Dispersive Near Edge X-Ray Absorption Fine Structure in the Soft X-Ray Region:   A New Technique to Investigate Surface Reactions

Amemiya, Kenta; Kondoh, Hiroshi; Nambu, Akira; Iwasaki, M.; Nakai, Ikuyo; Yokoyama, Toshihiko; Ohta, Toshiaki

doi:10.1143/jjap.40.l718

Cited by 20 publications

(10 citation statements)

References 10 publications

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“…15,16 By combining energy-dispersed x-rays and a position sensitive electronenergy analyzer, a NEXAFS spectrum from submonolayer adsorbate can be obtained simultaneously in several tens seconds. We recently developed a new method, energydispersive near edge x-ray absorption fine structure ͑dispersive-NEXAFS͒ spectroscopy.…”

mentioning

confidence: 99%

Reaction-path switching induced by spatial-distribution change of reactants: CO oxidation on Pt(111)

Nakai

Kondoh

Amemiya

et al. 2004

The Journal of Chemical Physics

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We studied the mechanism of CO oxidation on O-covered Pt(111) surfaces during CO exposure by means of time-resolved near edge x-ray absorption fine structure spectroscopy. Two distinct reaction processes were found to occur sequentially; isolated O atoms and island-periphery O atoms contribute to each process. Combination of in situ monitoring of the reaction kinetics and Monte Carlo simulations revealed that CO coadsorption plays a role of inducing the dynamic change in spatial distribution of O atoms, which switches over the two reaction paths.

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mentioning

confidence: 99%

Reaction-path switching induced by spatial-distribution change of reactants: CO oxidation on Pt(111)

Nakai

Kondoh

Amemiya

et al. 2004

The Journal of Chemical Physics

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“…valence photoemission, electron energy loss spectroscopy, etc. ), as well as soft X-ray-based experiments (X-ray emission spectroscopy or time-resolved X-ray absorption spectroscopy [13]). With further development to add front end coatings sensitive to visible and IR radiation (probably requiring encapsulation due to the extreme surface sensitivity of the coatings), this detector could also find use in laser spectroscopy.…”

Section: Conclusion and Future Prospectsmentioning

confidence: 99%

An Ultra-High-Speed Detector for Synchrotron Radiation Research

Bussat¹

2004

AIP Conference Proceedings

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Current Evaluation of Performance: • Spatial Resolution: ~100 µm (∼2 channels), probably better • Data readout: 200 µs with buffer memory (in progress) • Linearity: linear up to 1.4 MHz/Channel → 1.1 GHz total • Size: small enough to fit existing spectrometers (Scienta, PHI,…) • Stability and Reliability: working at the ALS BL4 since 06/29/03 • Bakeable up to 100 degree C → UHV compatible Some future experiments: • Minutes → seconds photoelectron diffraction/holography for surfaces & nanostructures, time-resolved valence-band spectroscopy • Time-resolved surface reaction studies: steady-state or pump-probe • Time-resolved magnetization studies, incl. MCD • Other applications: time-resolved near-edge x-ray absorption fine structure • Laser spectroscopy with visible/IR photocathode on MCPs Motivation Many experiments at 3 rd (soon 4 th) generation synchrotron radiation sources only possible with GHz-rate linear detection of electrons or photons, leading to: Publications J.

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“…However, it takes usually more than several minutes to measure a spectrum from submonolayer adsorbates, which restricts the investigation of surface reaction. Recently, we have developed a dispersive-NEXAFS spectroscopy, which enables us to obtain a spectrum within approximately 10 s. Thus, the in situ observations of various surface reactions have been conducted to obtain the real-time coverage changes of reaction species. − …”

Section: Introductionmentioning

confidence: 99%

Mechanism of Ammonia Formation on Rh(111) Studied by Dispersive Near-Edge X-ray Absorption Fine Structure Spectroscopy

et al. 2010

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The reaction mechanism of ammonia formation on a Rh(111) surface was investigated by means of dispersive near-edge X-ray absorption fine structure (dispersive-NEXAFS) spectroscopy. Nitrogen-covered Rh(111) surfaces were exposed to gaseous hydrogen (1.0−5.0 × 10−7 Torr) at constant surface temperatures (330−390 K) to form ammonia which desorbs immediately from the surface. Continuous data acquisition of nitrogen K-edge NEXAFS spectra enables us to monitor coverage changes of surface species during the progress of the reaction. The obtained NEXAFS spectra were well reproduced by summation of the standard spectra for N and NH. We found that the NH species, which is considered as a stable intermediate, is not only hydrogenized to NH3, but also decomposed into N and H under H2-lacking conditions. The reaction-order analyses indicate that the NH decomposition occurs at periphery of 2-dimensional islands of NH while the NH3 formation takes place most likely over the entire NH islands. We propose a two-step reaction mechanism: (1) formation of NH islands and (2) hydrogenation of the NH species to NH3. The former process reaches equilibrium with decomposition after a short period.

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Energy Dispersive Near Edge X-Ray Absorption Fine Structure in the Soft X-Ray Region: A New Technique to Investigate Surface Reactions

Cited by 20 publications

References 10 publications

Reaction-path switching induced by spatial-distribution change of reactants: CO oxidation on Pt(111)

Reaction-path switching induced by spatial-distribution change of reactants: CO oxidation on Pt(111)

An Ultra-High-Speed Detector for Synchrotron Radiation Research

Mechanism of Ammonia Formation on Rh(111) Studied by Dispersive Near-Edge X-ray Absorption Fine Structure Spectroscopy

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