The Wagner plot and the Auger parameter as tools to separate initial- and final-state contributions in X-ray photoemission spectroscopy

Moretti, Giuliano

doi:10.1016/j.susc.2013.09.009

Cited by 57 publications

(37 citation statements)

References 147 publications

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“…Cu ? state was identified according to the binding energy of the Cu 2p 3/2 peak and modified Auger parameter [24,25]. Relative intensities of peaks determined form high resolution Cu 2p spectra are used to calculate the concentration of oxidation states of copper at surface.…”

Section: Resultsmentioning

confidence: 99%

Synthesis and characterization of chitosan–copper nanocomposites and their fungicidal activity against two sclerotia-forming plant pathogenic fungi

et al. 2017

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In this report, the metal-vapor synthesis (MVS) was used for the preparation of copper nanoparticles which was then used for the preparation of chitosan-copper nanocomposite. The antifungal activity of Cu@Chit NCs against two sclerotium-forming plant pathogenic fungi Sclerotium rolfsii (S. rolfsii) and Rhizoctonia solani (R. solani) AG-4 was evaluated in vitro and their effects on hyphal morphology, and sclerotia formation were observed for the first time. The NCs were prepared through impregnation of chitosan with colloid solution of copper nanoparticles in organic solvent (acetone or toluene). Transmission electron microscopy shows that the particles have predominantly spherical form, polydisperse character, the mean diameter about 2-3 nm and a rather uniform distribution in the chitosan matrice. Analysis of the small angle scattering curves suggests that the copper particles in the NCs with the size of B2 nm are mostly located in the chitosan pores with the same size. The effect of Cu@Chit NCs on fungal growth reveals some significant inhibitory activity against two tested fungi. The highest level of inhibition against S. rolfsii and R. solani AG-4 was observed using the high concentrations of Cu@Chit NC prepared using acetone as a solvent. A loss of the cytoplasm content, cytoplasmic coagulation, irregular shape of mycelia, or destruction in the hyphae was confirmed. The experiments demonstrate that the Cu@Chit NC synthesized via MVS using acetone was more effective than that of toluene in inhibiting fungal hyphae growth against R. solani AG-4 and S. rolfsii. The results show that the Cu@Chit NCs are fungicidal against both the tested fungus at high concentrations and the fungicidal or fungistatic activity is dependent on the tested fungus species.

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Section: Resultsmentioning

confidence: 99%

Synthesis and characterization of chitosan–copper nanocomposites and their fungicidal activity against two sclerotia-forming plant pathogenic fungi

et al. 2017

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“…Therefore, the upshift of Ag 3d BE in Ag/Si 3 N 4 -O-673 is not caused by the change of oxidation state, but more likely due to size effect 34,35 . It has been validated that the screening of core holes in ultra-small metal nanoclusters becomes limited which results in an upshift of corelevel BEs [36][37][38][39] . Hence, the upshift of Ag 3d BE is ascribed to the decreasing size of Ag aggregates from micrometer to subnanometer.…”

Section: Ex Situ Characterization Of Oxidation-induced Dispersion Ofmentioning

confidence: 99%

“…Regarding the oxidation state of silver, it is unable to distinguish oxide or metallic state using XPS core-levels 12,33 . Alternatively, Auger Parameters (AP, α) (see the description of Auger parameter in the Supplementary Discussion) defined as the sums of Auger kinetic energy (KE) and photoelectron BE are often used to identify the chemical state of elements including Cu, Ag, Zn, etc 37,40,41 . Auger spectra of Ag MNN are shown in supplementary Fig.…”

Section: Ex Situ Characterization Of Oxidation-induced Dispersion Ofmentioning

confidence: 99%

In situ identification of the metallic state of Ag nanoclusters in oxidative dispersion

Zhu

et al. 2021

Nat Commun

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Oxidative dispersion has been widely used in regeneration of sintered metal catalysts and fabrication of single atom catalysts, which is attributed to an oxidation-induced dispersion mechanism. However, the interplay of gas-metal-support interaction in the dispersion processes, especially the gas-metal interaction has not been well illustrated. Here, we show dynamic dispersion of silver nanostructures on silicon nitride surface under reducing/oxidizing conditions and during carbon monoxide oxidation reaction. Utilizing environmental scanning (transmission) electron microscopy and near-ambient pressure photoelectron spectroscopy/photoemission electron microscopy, we unravel a new adsorption-induced dispersion mechanism in such a typical oxidative dispersion process. The strong gas-metal interaction achieved by chemisorption of oxygen on nearly-metallic silver nanoclusters is the internal driving force for dispersion. In situ observations show that the dispersed nearly-metallic silver nanoclusters are oxidized upon cooling in oxygen atmosphere, which could mislead to the understanding of oxidation-induced dispersion. We further understand the oxidative dispersion mechanism from the view of dynamic equilibrium taking temperature and gas pressure into account, which should be applied to many other metals such as gold, copper, palladium, etc. and other reaction conditions.

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“…Greater confidence can be found in using the x-ray induced Auger lines to aid chemical state identification as described by Wagner 88 and utilizing Auger parameters and chemical state plots (commonly called Wagner plots) 89,90 . The usefulness of such analysis in chemical state identification is widely reported and exemplified by the work of Moretti and co-workers [91][92][93][94] .…”

Section: B Chemical State Identification and Auger Linesmentioning

confidence: 99%

Practical guide for x-ray photoelectron spectroscopy: Applications to the study of catalysts

Davies

Morgan

2020

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

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X-ray photoelectron spectroscopy (XPS) has become a standard tool for the study of catalytic materials over the last two decades and with the increasing popularity of turnkey XPS systems, the analysis of these types of materials is open to an even wider audience. However, increased accessibility leads to an increase in the number of new or inexperienced practitioners, leading to erroneous data collection and interpretation. Over many years of working on a wide range of catalytic materials, we have developed procedures for the planning and execution of XPS analysis and subsequent data analysis, and this guide has been produced to help users of all levels of expertise to question their approach towards analysis and get the most out of the technique and avoiding some common pitfalls.

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The Wagner plot and the Auger parameter as tools to separate initial- and final-state contributions in X-ray photoemission spectroscopy

Cited by 57 publications

References 147 publications

Synthesis and characterization of chitosan–copper nanocomposites and their fungicidal activity against two sclerotia-forming plant pathogenic fungi

Synthesis and characterization of chitosan–copper nanocomposites and their fungicidal activity against two sclerotia-forming plant pathogenic fungi

In situ identification of the metallic state of Ag nanoclusters in oxidative dispersion

Practical guide for x-ray photoelectron spectroscopy: Applications to the study of catalysts

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