Surface and Interface Characterization

Seah, M. P.; Chiffre, Leonardo De

doi:10.1007/978-3-540-30300-8_6

Cited by 7 publications

(5 citation statements)

References 138 publications

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“…We now see that there is a more effective way of describing the M 2 dependence. Elsewhere, 45 in analysing the effects for Ne and Xe primary ions, we have similar plots where, in each case, the values of the sputtering yield rise as a function of M 2 to a constant plateau value for M 2 > 100. Superimposed on this rise at low M 2 is a broad peak whose intensity and position depend on M 1 .…”

Section: Unique Constants For Each Target Atom In This Adaptation Of mentioning

confidence: 93%

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An accurate semi‐empirical equation for sputtering yields I: for argon ions

Seah¹,

Clifford²,

Green³

et al. 2005

Surface & Interface Analysis

117

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An analysis has been made of the historical data for argon ion sputtering yields of 28 mono-elemental solids in the energy range 250-10 000 eV to develop an improved semi-empirical formula based on Matsunami et al.'s and Yamamura and Tawara's formulations. The best result is found if an essential component involving the target density is included in Matsunami et al.'s approach. The scatter between the predictions and the experimental data is reduced to 9.0% by generating an analytical expression for the term Q that requires none of the target-specific numbers from special look-up tables of the type used by Matsunami et al. and Yamamura and Tawara. For elements other than the 34 elements for which Q values are tabulated, the new Q values range up to a factor of 5 from the default value that they recommend.The predictions are tested by a new method for determining sputtering yields using atomic force microscopy to measure very small crater volumes sputtered in ultrahigh vacuum. Here, 26 mono-elemental targets were studied using a 5 keV argon ion beam set at 45• to the surface normal. The effect of the angle of incidence is evaluated best using Yamamura et al.'s angular equations for this contribution. Results for Sb, Te and Bi indicate a significantly higher sputtering yield than expected. This is thought to arise from the high content of polyatomic groups associated with the low sublimation energies for such clusters in the pure elements of groups V-B and VI-B of the Periodic

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Section: Unique Constants For Each Target Atom In This Adaptation Of mentioning

confidence: 93%

“…As noted later, the Q values depend on M 1 and so, for general use for other incident ions, these Q eff values may then need to be studied further. 45 In Fig. 1 we add a curve for the expression used by Steinbruchel 9 for comparison.…”

Section: Fitting To Published Experimental Datamentioning

confidence: 99%

An accurate semi‐empirical equation for sputtering yields I: for argon ions

Seah¹,

Clifford²,

Green³

et al. 2005

Surface & Interface Analysis

117

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“…54 Note that the scattering intensities of each peak are related to incident laser intensity, molecular vibration frequencies, and the change in molecular polarizability and is not indicative of film thickness or amount while peak broadening arises from anharmonicities such as chemical (elemental) and physical (crystallinity) inhomogeneity. 56 There were no magnesium carbonate related samples in the RRUFF database which possessed a peak at 1075 cm −1 but carbonate peaks are known to occur in the range of wavenumbers with magnesite, MgCO 3 , possessing a peak at 1095 cm −1 . The peak observed at 982 cm −1 is indicative of an SO 4 2− containing species which most closely resembles the standard spectrum of epsomite (MgSO 4 · 7H 2 O).…”

Section: Potentiostatic Polarization Ofmentioning

confidence: 99%

The Role of Surface Films and Dissolution Products on the Negative Difference Effect for Magnesium: Comparison of Cl⁻versus Cl⁻Free Solutions

Cain

Gonzalez-Afanador

Birbilis

et al. 2017

J. Electrochem. Soc.

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The anodic dissolution and associated hydrogen evolution of high purity Mg (80 ppmw Fe) was studied as a function of potential in unbuffered 0.6 M NaCl (pH ≈ 8.5), 0.6 M NaCl saturated with Mg(OH) 2 (pH ≈ 10.25), 0.1 M MgCl 2 (pH ≈ 5.6), 0.1 M Na 2 SO 4 (pH ≈ 5.5), and a 0.1 M Tris(hydroxymethyl)aminomethane hydrochloride (TRIS, pH ≈ 7.25) buffer solution via simultaneous mass loss, hydrogen volume collection, potentiostatic and potentiodynamic polarization, and inductively coupled plasma-optical emission spectroscopy (ICP-OES). The negative difference effect (NDE) was substantial in the unbuffered Cl − containing environments where Mg(OH) 2 formed on the surface and weak in 0.1 M Na 2 SO 4 . In contrast, the 0.1 TRIS buffered solution exhibited a positive difference effect and the absence of thick corrosion films. Mg(OH) 2 films formed on samples in Cl − spalled off easily whilst the Mg(OH) 2 films formed in 0.1 M Na 2 SO 4 were more tenacious, which suggests that film stability plays significant role in the NDE. Research and development of magnesium (Mg) and its alloys has greatly increased in the last 15 years primarily due to the demand for lightweight vehicles in the automotive and aerospace industries, 1 in addition to the exploration of Mg as an anode material in primary and secondary batteries.2 However, the poor corrosion resistance and complex dissolution behavior of Mg has limited its wider use as an engineering material.3-5 One aspect associated with Mg dissolution which has not to date been mechanistically elucidated in full, is the phenomenon known as the negative difference effect (NDE).3 This effect is characterized by an increase in the rate of hydrogen evolution with increasing anodic overpotential relative to the open circuit -which provides a local cathodic reaction for a significant portion of the anodic reaction.6 This phenomenon confounds the understanding of Mg dissolution mechanisms, establishment of a Tafel law and other reaction kinetic parameters, as well as other issues including accurate analysis of corrosion rates from electrochemical impedance spectroscopy (EIS). [7][8][9] There are several theories purporting to explain the origins of the NDE among which include noble impurity element enrichment, 10,11 non-faradaic mass loss via metal spalling, 12,13 formation and dissolution of hydrides and partially protective films, [14][15][16][17] and univalent Mg based dissolution followed by further oxidation of Mg + →Mg 2+ in solution (leading to hydrogen evolution from the reduction of water away from the electrode in the electrolyte);18 however, no consensus has been reached on the physical origins of the NDE.The contemporary paradigm for the manifestation of the NDE centers on evidence for the enhanced cathodic activity of dissolving Mg anodes;19 whereby numerous works confined within a relatively recent timeframe have elucidated such a phenomenon. Evidence of enhanced cathodic activity has been reported by Williams and coworkers through use of the scanning vibrating electrode techniqu...

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“…For the purposes of energy calibration, a PES spectrum of the Au 4f electrons was recorded immediately after each C 1s and S 2p measurement on the same region of the sample surface. The Au 4f 7/2 photoelectron at 84.0 eV 42,43 was then used to convert from kinetic energy to binding energy scales. Furthermore, the C 1s and S 2p spectra from freshly prepared dodecane thiolate monolayers on Au were recorded periodically to serve as absolute calibration standards.…”

Section: Equationmentioning

confidence: 99%

Near-Edge X-ray Absorption Fine Structure Spectroscopy of Diamondoid Thiol Monolayers on Gold

et al. 2008

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Diamondoids, hydrocarbon molecules with cubic-diamond-cage structures, have unique properties with potential value for nanotechnology. The availability and ability to selectively functionalize this special class of nanodiamond materials opens new possibilities for surface-modification, for high-efficiency field emitters in molecular electronics, as seed crystals for diamond growth, or as robust mechanical coatings. The properties of self-assembled monolayers (SAMs) of diamondoids are thus of fundamental interest for a variety of emerging applications. This paper presents the effects of thiol substitution position and polymantane order on diamondoid SAMs on gold using nearedge X-ray absorption fine structure spectroscopy (NEXAFS) and X-ray photoelectron spectroscopy (XPS). A framework to determine both molecular tilt and twist through NEXAFS is presented and reveals highly ordered diamondoid SAMs, with the molecular orientation controlled by the thiol location. C 1s and S 2p binding energies are lower in adamantane thiol than alkane thiols on gold by 0.67 ± 0.05 eV and 0.16 ± 0.04 eV respectively. These binding energies vary with diamondoid monolayer structure and thiol substitution position, consistent with different amounts of steric strain and electronic interaction with the substrate. This work demonstrates control over the assembly, in particular the orientational and electronic structure, providing a flexible design of surface properties with this exciting new class of diamond clusters.3

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Surface and Interface Characterization

Cited by 7 publications

References 138 publications

An accurate semi‐empirical equation for sputtering yields I: for argon ions

An accurate semi‐empirical equation for sputtering yields I: for argon ions

The Role of Surface Films and Dissolution Products on the Negative Difference Effect for Magnesium: Comparison of Cl⁻versus Cl⁻Free Solutions

Near-Edge X-ray Absorption Fine Structure Spectroscopy of Diamondoid Thiol Monolayers on Gold

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Surface and Interface Characterization

Cited by 7 publications

References 138 publications

An accurate semi‐empirical equation for sputtering yields I: for argon ions

An accurate semi‐empirical equation for sputtering yields I: for argon ions

The Role of Surface Films and Dissolution Products on the Negative Difference Effect for Magnesium: Comparison of Cl−versus Cl−Free Solutions

Near-Edge X-ray Absorption Fine Structure Spectroscopy of Diamondoid Thiol Monolayers on Gold

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The Role of Surface Films and Dissolution Products on the Negative Difference Effect for Magnesium: Comparison of Cl⁻versus Cl⁻Free Solutions