Nondestructive in‐depth composition profile of oxy‐hydroxide nanolayers on iron surfaces from ARXPS measurement

Olla, Maurizio; Navarra, G.; Elsener, Bernhard; Rossi, Antonella

doi:10.1002/sia.2362

Cited by 51 publications

(53 citation statements)

References 42 publications

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“…Secondary ion mass spectroscopy (SIMS) and depth profiling by Auger electron spectroscopy and XPS could provide an accurate estimate of the overlayer thickness, but these methods are destructive. Alternately, the overlayer thickness can be determined non-destructively by XPS 53,54,[59][60][61][62][63][64][65] . Since most NEXAFS endstations at modern synchrotron facilities include XPS spectrometers, the calculation of the overlayer thickness can be performed by acquiring XPS spectra in the same experimental chamber, thus avoiding any risk of changing the composition and thickness of the contamination layer upon transferring the sample to a dedicated XPS chamber.…”

Section: Resultsmentioning

confidence: 99%

“…For electron yield NEXAFS spectroscopy of low-Z elements, the information depth (the specimen thickness measured normal to the surface from which a specified percentage of typically 95% of the detected signal originates) is usually less than 5 nm 1 . Unfortunately, the assumption of chemical and structural homogeneity does not hold in the vast majority of solid surfaces due to the presence of complex surface-bound species and layers, e.g., natural oxide and contamination layers 53,54 . This can lead to significant errors when analyzing elements that are simultaneously present in multiple layers.…”

Section: Introductionmentioning

confidence: 99%

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Accounting for Nanometer-Thick Adventitious Carbon Contamination in X-ray Absorption Spectra of Carbon-Based Materials

et al. 2014

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Near-edge X-ray absorption fine structure (NEXAFS) spectroscopy is a powerful technique for characterizing the composition and bonding state of nanoscale materials and the top few nanometers of bulk and thin film specimens. When coupled with imaging methods like photoemission electron microscopy, it enables chemical imaging of materials with nanometerscale lateral spatial resolution. However, analysis of NEXAFS spectra is often performed under the assumption of structural and compositional homogeneity within the nanometer-scale depth probed by this technique. This assumption can introduce large errors when analyzing the vast majority of solid surfaces due to the presence of complex surface and near-surface structures such as oxides and contamination layers. An analytical methodology is presented for removing the contribution of these nanoscale overlayers from NEXAFS spectra of two-layered systems to provide a corrected photo-absorption spectrum of the substrate. This method relies on the subtraction of the NEXAFS spectrum of the overlayer adsorbed on a reference surface from the spectrum of the two-layer system under investigation, where the thickness of the overlayer is independently determined by X-ray photoelectron spectroscopy (XPS). This approach is applied to NEXAFS data acquired for one of the most challenging cases: air-exposed hard carbon-based materials with adventitious carbon contamination from ambient exposure. The contribution of the adventitious carbon was removed from the as-acquired spectra of ultrananocrystalline diamond (UNCD) and hydrogenated amorphous carbon (a-C:H) to determine the intrinsic photoabsorption NEXAFS spectra of these materials. The method alters the calculated fraction of sp 2 -hybridized carbon from 5 to 20%, and reveals that the adventitious contamination can be

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Accounting for Nanometer-Thick Adventitious Carbon Contamination in X-ray Absorption Spectra of Carbon-Based Materials

et al. 2014

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“…The oxygen 1s signal was composed of three peaks: the first at 530.3 ± 0.1 eV being assigned to oxygen in iron and zinc oxides [7,57,58], the main peak at 531.7 ± 0.1 eV to non-bridging oxygen (NBO) in polyphosphates and to oxygen bound to carbon [7,59,60] and the high-binding-energy peak at 533.4 eV to bridging oxygen (BO) in polyphosphates [60,61].…”

Section: Xps Resultsmentioning

confidence: 99%

Pressure Dependence of ZnDTP Tribochemical Film Formation: A Combinatorial Approach

2007

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Combinatorial testing has been performed on zinc dialkyldithiophosphate (ZnDTP)-containing lubricants, to investigate the effects of contact pressure on the formation of tribochemical films. Contact pressures ranging from 25 to 500 MPa were applied in ball-on-disc tribotests with oscillating load. Both the ball and the disc were investigated by means of small-area and imaging X-ray photoelectron spectroscopy (XPS). The thickness and the composition of the reaction layer were estimated from the XPS data. The thickness of the reaction layer in the tribologically stressed areas of the ball and of the disc increased with both temperature and contact pressure. The reaction layer mainly consisted of short-chain poly(thio)phosphates, shorter chains being observed at higher contact pressures. At high pressures, the presence of a thick, high-toughness short-chain poly(thio)phosphate layer can explain the lower friction and dimensional wear coefficients observed. On the ball, similar anti-wear film formation mechanisms were observed as on the disc, zinc sulphide being deposited in the post-contact region.

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“…(BE = 710.5 eV, FWHM = 2.4 eV) and Fe 2? (BE = 709.0 eV, FWHM = 2.4 eV) with a Gaussian:Lorenzian ratio of 45:55 [50]. UV/Vis spectra were recorded at room temperature with a Perkin Elmer Lambda 20.…”

Section: Instruments and Characterizationmentioning

confidence: 99%

Simultaneous formation of ferrite nanocrystals and deposition of thin films via a microwave-assisted nonaqueous sol–gel process

Bilecka

Kubli

Amstad

et al. 2010

J Sol-Gel Sci Technol

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Combination of the surfactant-free nonaqueous sol-gel approach with the microwave technique makes it possible to synthesize Fe 3 O 4 , CoFe 2 O 4 , MnFe 2 O 4 , and NiFe 2 O 4 nanoparticles of about 5-6 nm and with high crystallinity and good morphological uniformity. The synthesis involves the reaction of metal acetates or acetylacetonates as precursors with benzyl alcohol at 170°C under microwave irradiation of 12 min. Immersion of glass substrates in the reaction solution results in the deposition of homogeneous metal ferrite films whose thickness can be adjusted through the precursor concentration. If preformed nickel nanoparticles are used as a type of curved substrate, the ferrite nanoparticles coat the seeds and form core-shell structures. These results extend the microwave-assisted nonaqueous sol-gel approach beyond the simple synthesis of nanoparticles to the preparation of thin films on flat or curved substrates.

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Nondestructive in‐depth composition profile of oxy‐hydroxide nanolayers on iron surfaces from ARXPS measurement

Cited by 51 publications

References 42 publications

Accounting for Nanometer-Thick Adventitious Carbon Contamination in X-ray Absorption Spectra of Carbon-Based Materials

Accounting for Nanometer-Thick Adventitious Carbon Contamination in X-ray Absorption Spectra of Carbon-Based Materials

Pressure Dependence of ZnDTP Tribochemical Film Formation: A Combinatorial Approach

Simultaneous formation of ferrite nanocrystals and deposition of thin films via a microwave-assisted nonaqueous sol–gel process

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