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Coulomb repulsion between the bonding electron pair in the H-O covalent bond (denoted by "-") and the nonbonding electron pair of O (":") and the specific-heat disparity between the O:H and the H-O segments of the entire hydrogen bond (O:H-O) are shown to determine the O:H-O bond angle-length-stiffness relaxation dynamics and the density anomalies of water and ice. The bonding part with relatively lower specific-heat is more easily activated by cooling, which serves as the "master" and contracts, while forcing the "slave" with higher specific-heat to elongate (via Coulomb repulsion) by different amounts. In the liquid and solid phases, the O:H van der Waals bond serves as the master and becomes significantly shorter and stiffer while the H-O bond becomes slightly longer and softer (phonon frequency is a measure of bond stiffness), resulting in an O:H-O cooling contraction and the seemingly "regular" process of cooling densification. In the water-ice transition phase, the master and the slave swap roles, thus resulting in an O:H-O elongation and volume expansion during freezing. In ice, the O--O distance is longer than it is in water, resulting in a lower density, so that ice floats.

Goldschmidt-Pauling contraction of the H-O polar-covalent bond elongates and polarizes the other noncovalent part of the hydrogen bond (O:H-O), that is, the O:H van der Waals bond, significantly, through the Coulomb repulsion between the electron pairs of adjacent oxygen (O-O). This process enlarges and stiffens those H2O molecules having fewer than four neighbors such as molecular clusters, hydration shells, and the surface skins of water and ice. The shortening of the H-O bond raises the local density of bonding electrons, which in turn polarizes the lone pairs of electrons on oxygen. The stiffening of the shortened H-O bond increases the magnitude of the O1s binding energy shift, causes the blue shift of the H-O phonon frequencies, and elevates the melting point of molecular clusters and ultrathin films of water, which gives rise to their elastic, hydrophobic, highly-polarized, ice-like, and low-density behavior at room temperature.

Raman phonon relaxation dynamics in carbon allotropes including graphene, carbon nanotube, C60, carbon nanobud, graphite, and diamond has been formulated in terms of the bond order–length–strength (BOLS) correlation. The length and energy responses of the representative bond to the change of coordination environment, pressure, and temperature determine intrinsically the Raman shifts. Reproduction of the measured results in quantitative information of the bond length, bond energy, mode cohesive energy, binding energy density, Debye temperature, and the compressibility of the C–C bond in each phase without needing involvement of the phonon scattering resonant processes or the mode Gruneisen constants. 2013 Elsevier B.V. All rights reserved.

Maximum normal stress criterion can be used to determine the cracking angle in the uniform and non-uniform zone. According to this theory, the propagating process of the crack in non-uniform composite material is simulated based on the finite element method. The results show that the crack advances wave-like and basically along the direction perpendicular to the maximum normal stress, which is of great guiding significance for the fracture resistance of such kind of structure.

It is assumed that the physical parameters of functionally graded coating material accords with the variation of degree n polynomial, and based on this material model, the behavior of crack fracture on the interface of functionally graded coating is studied. The results show that when the functionally graded coating structure bears a tension load, stress intensity factors of mode I and mode II exist at the same time generally, and the intensity factor of mode I occupies a leading position all along. Besides, when the elastic modulus ratio of the base to the functionally graded coating top is 5 and the elastic modulus of functionally graded coating varies linearly, the stress intensity factor of interface crack is the smallest, and with the increasing of elastic modulus ratio, the optimal non-uniform parameter tends to be larger than 1.

Two-dimensional crystals stacked by van der Waals coupling, such as twisted graphene and coupled graphene-BN layers with unusual phenomena have been a focus of research recently. As a typical representative, with the modulation of structural symmetry, stacking orders and spin-orbit coupling, transitional metal dichalcogenides have shown a lot of fascinating properties. Here we reveal the effect of stacking orders with spin-orbit coupling on the electronic properties of few-layer 3R-type MoS2 by first principles methods. We analyze the splitting of states at the top of valence band and the bottom of conduction band, following the change of stacking order. We find that regardless of stacking orders and layers’ number, the spin-up and spin-down channels are evidently separated and can be as a basis for the valley dependent spin polarization. With a model Hamiltonian about the layer’s coupling, the band splitting can be effectively analyzed by the coupling parameters. It is found that the stacking sequences, such as abc and abca, have the stronger nearest-neighbor coupling which imply the popular of periodic abc stacking sequence in natural growth of MoS2.

Based on DFT and Berry curvature calculations, we predict that quantum anomalous hall effect (QAHE) can be realized in two dimensional anti-ferromagnetic (AFM) NiRuCl6 with zero net magnetic moment. By tuning spin-orbits coupling (SOC), we find that the topological properties of NiRuCl6 come from its energy band reversal. The results indicate that NiRuCl6 behaves as AFM Chern insulator and its spin-polarized electronic structure and strong spin-orbits coupling (SOC) are the origin of QAHE. Considering the compatibility between AFM and insulator, AFM Chern insulator is more suitable to realize high temperature QAHE because generally Neel temperature of AFM systems is more easily improved than Curie temperature of ferromagnetic (FM) systems. Due to the different magnetic coupling mechanism between FM and AFM Chern insulator, AFM Chern insulator provides a new way to archive high temperature QAHE in experiments., 6 pages, 6 figures

Sixty basic rules govern the O:H–O bond relaxation and electron polarization and their consequences on detectable properties of water and ice such as the phonon frequencies, O 1s binding energy shift, crystal geometry, H–O phonon lifetime, mass density, elasticity, hydrophobicity, fluidity, lubricity, supersolidity, quasisolidity, viscosity, skin stress, skin solubility, molecular dynamics, degree of fluctuation, thermal stability and their interdependence.

Phonon spectrometrics and contact-angle measurements revealed the essentiality of anti-HB (hydrogen bond), super-HB, and electrified-HB representing molecular interactions in the Lewis acid, base, and adduct (salt) solutions, respectively. Hydronium creation (H3O tetrahedron with one lone pair) in acid solution results in the H↔H anti-HB that breaks the O:H–O bond network, diluting blood flow for instance; hydroxide (OH tetrahedron with three lone pairs) leads to the O:↔:O super-HB that serves as a point compressor to the hydration network, releasing heat by softening the H–O bond at hydrating. Salt ions create each an electric field that aligns, clusters, polarizes, and stretches water molecular dipoles in a supersolid hydration-shell manner. The electrification-induced phonon relaxation disperses the quasisolid phase boundary outwardly and hence lowers the freezing temperature and raises the melting point. O:H–O bond electrification also raise the viscosity, skin stress, H–O phonon lifetime, but depresses the order of fluctuation and the coefficient of molecular rotation and self-diffusion in the hydration shells. The extent of electrification is molecular site, solute concentration and type dependent, following the Hofmeister series.

Lagrangian solution of oscillator dynamics transforms the observed H–O bond and O:H nonbond lengths and their characteristic phonon frequencies (d x, ω x) into their respective force constants and cohesive energies (k x, E x), which results in mapping of the potential paths for the O:H–O bond cooperative relaxation under stimulus. Results show that molecular undercoordination not only reduces its size (d H) with enhanced H–O energy from the bulk value of 3.97 to 5.10 eV for a H2O monomer but also enlarges their separation (d L) with O:H energy reduction from 95 to 35 meV for a dimer. The H–O energy gain raises the melting point of water skin from the bulk value 273 to 310 K, and the O:H energy loss lowers the freezing temperature of a 1.4 nm sized droplet from the bulk value 258 to 202 K. However, compression does the opposite to molecular undercoordination on bond relaxation but the same on polarization.

A solute forms a hydration shell by clustering water molecular dipoles surrounding it, which elongates the O:H–O bond in the shell and stiffens its H–O phonon and softens the O:H–O nonbond phonon by different extents. Polarization dominance of salt solutions raises the H–O phonon lifetime, molecular structural order, skin stress, solution viscosity, and thermal stability. Quantum fragmentsation of acid solutions weakens molecular structural order, skin stress, and the reflectivity of Raman photon and the transmittance of IR photons. The difference in electronegativity, electronic structure, and ionic size between H+ and other alkali metals could be origin.

As an often overlooked degree of freedom, molecular undercoordination shortens the H–O polar-covalent bond and stiffens its phonon but lengthens and softens the O:H nonbond more significantly through the Coulomb repulsion between the electron pairs of adjacent oxygen. This process shrinks those H2O molecules having fewer-than-four neighbors such as molecular clusters, hydration shells, and the surface skin of water and ice. The shortening of the H–O bond raises the local density of bonding electrons, which in turn polarizes the lone pairs of electrons on oxygen forming anchored dipoles pointing outwardly. The stiffening of the shortened H–O bond increases the magnitude of the O 1s binding energy shift, causes the blueshift of the H–O phonon frequencies, and elevates the melting point of molecular clusters and ultrathin films of water, which gives rise to their elastic, hydrophobic, ice-like, frictionless, and low-density behavior irrespective of temperature.

Phonon spectrometric mapping of the O:H–O bond relaxation dynamics across the phase diagram along the following paths confirmed the reality of the O:H–O cooperativity mechanism: (i) liquid water at 300 K and ice at 80 K as a function of pressure, (ii) liquid water cooling from 350 to 80 K under the ambient pressure, (iii) mechanical freezing of the ambient water under compression up to 4.0 GPa, and, (iv) liquid water heating from 253 to 753 K under 30 MPa pressure. Observations classify the TC(P) phase boundaries of water and ice into four types according to their slopes. O:H compression dictates the positively-sloped such as Vapor/Liquid boundaries; the H–O elongation dictates the negatively-sloped such as VII/VIII boundaries, while O:H–O frozen dictates the XI/Ic constant TC boundary and the symmetrical relaxation governs the X/(VII, VIII) constant PC boundaries.

A combination of the electrification-induced quasisolidity and the undercoordination-induced skin supersolidity laid foundations for the water floating bridge, electrofreezing and electromelting of liquid water. Both electrification and molecular undercoordination disperse the quasisolid phase boundaries, which not only depresses the freezing temperature and molecular dynamics but also raises the melting point, H–O phonon lifetime, skin stress, and viscosity. The extent of quasisolidity is charge quantity and sign dependent. Aqueous solutions weaken the field of capacitors or charged particles, so aqueous solutions destabilize the floating bridge and wet faster soil particles.

Superlubricity means non-sticky and frictionless when two bodies are set contacting motion. Although this occurrence has been extensively investigated since 1859 when Faraday firstly proposed a quasiliquid skin on ice, the mechanism behind the superlubricity remains debating. This chapter features a consistent understanding of the superlubricity pertaining to the slipperiness of ice, self-lubrication of dry solids, and aqueous lubricancy from the perspective of skin bond-electron-phonon adaptive relaxation. The presence of nonbonding electron polarization, atomic or molecular undercoordination, and solute ionic electrification of the hydrogen bond as an addition, ensures the superlubricity. Nonbond vibration creates soft phonons of high magnitude and low frequency with extraordinary adaptivity and recoverability of deformation. Molecular undercoordination shortens the covalent bond with local charge densification, which in turn polarizes the nonbonding electrons making them localized dipoles. The locally pinned dipoles provide force opposing contact, mimicking maglev and hovercraft.

Consistency in experimental observations, numerical calculations, and theoretical predictions revealed that skins of 25 °C water and −(15-20) °C ice share the same attribute of supersolidity characterized by the identical H–O vibration frequency of 3450 cm−1. Molecular undercoordination and inter-electron-pair repulsion shortens the H–O bond and lengthen the O:H nonbond, leading to a dual process of nonbonding electron polarization. This relaxation-polarization process enhances the dipole moment, elasticity, viscosity, thermal stability of these skins with 25 % density loss, which is responsible for the hydrophobicity and toughness of water skin and the superfluidity in a microchannel.

As the basic structure element, hydrogen bond (O:H–O) is universal to all phases of water and ice irrespective geometric configuration or fluctuation order. The O:H–O bond integrates the asymmetric, coupled, short-range intermolecular and intramolecular interactions, whose segmental length and energy respond to stimulations sensitively in a “mater-slave” manner. If one segment shortens and turns to be stiffer, the other will expand and become softer. The O:H nonbond always relaxes more than the H–O bond in length. Such a manner of segmental cooperative relaxation and the associated polarization and bond angle relaxation discriminates ice and water from other substance in responding to stimuli of chemical, electrical, mechanical, thermal, and undercoordination effect, which reconcile almost all detectable properties of water and ice.

Solute ionic electrification of the O:H–O bond modulates significantly the critical pressures, temperatures, and gelation times for transiting aqueous solution into solid by dispersing the boundaries of the quasisolid phase. High-pressure in situ Raman spectrometrics revealed that transiting NaX solutions into ice VI and then into ice VII phase requires higher excessive pressures at 298 K temperature. The ΔPC varies in the order of Hofmeister series: X = I > Br > Cl > F ~ 0. Meanwhile, salting st​iffens the ωH and elongates the dOO throughout the course of compressure when transiting phase VII to phase X at even higher pressure. Recovering the electrification-shortened H–O bond needs excessive energy for the same sequence of phase transitions. Concentration dependence of the NaI solution indicates a different mechanism from that of solution type but it is similar to heating on the Liquid-VI-VII phase transition dynamics.

This paper introduces several applications of machine vision technology. With paneled CCD as the image sensor, the two-dimensional pictures of sample under study are inputted to a computer via the image grabbing card. After the preprocessing to the original image, image segmentation and feature extraction are carried on the target image, and the parameter value is figured out. The method is suitable for the parameter detection of the size, surface defect and color information, and have vast of application foreground.

In this paper, aiming at three material parameter functions of functionally graded coating (FGC) which have different continuities, the influence of functionally gradient coating material continuity on the fracture behaviors of the crack on the interface between the base material and coating is studied. The results show that when the functionally graded coating structure is under a tension load, if the ratio of maximum elastic modulus of the FGC to the elastic modulus of the base is less than 10, the functionally graded layer which has C02 continuity can help to improve the fracture resistance of the interface crack, and if the ratio increases continuously, the functionally graded layer which has C13 continuity can help to improve the fracture resistance of the interface crack, which is of great guiding significance for practical engineering design.

We demonstrate the stimulated Raman scattering (SRS) of a binary solution of toluene and m-xylene at different volume concentrations in liquid-core optical fiber (LCOF). The results show that SRS of three vibration modes of 1002 cm−1,2920 cm−1 and 3058 cm−1 bands are simultaneously generated at some volume concentrations. The 2920 cm−1 band and the 3058 cm−1 band are generated at one time, the SRS thresholds of the first-order Stokes of the 2920 cm−1 and 3058 cm−1 bands are lower compared with the second-order Stokes threshold of the 1002 cm−1 band and the main peak of the 2920 cm−1 and 3058 cm−1 bands changes from the 2920 cm−1 band to the 3058 cm−1 band as the volume concentrations are changed. We assume that these phenomena are attributed to the intermolecular Fermi resonance. Raman scattering cross section (RSCS) theory is used to explain this assumption.

Compared with link constant hangers, main-compensating constant hangers are structural symmetric, having high theoretical constant force. Swing cams are important component of the device, therefore the design of cam curve is the key of constant hangers. Based on the analysis of working principle of constant hangers, a mechanical model of constant hanger is established, and the differential equation of cam curve is derived by means of coordinate transformation .Meanwhile, spring parameters are determined. Curve equation is resolved and the cam curves are plotted. Then, the influence of spring parameters on cam curves is discussed. Finally, force values acting on the cam and the central rod are calculated according to cam curve. The simulations in this paper can be used to instruct the actual engineering design.

In this paper, J-integral of inhomogeneous welded joint is calculated by use of the combination of finite element method and virtual crack extension method, and the impact of strength matching on J-integral is studied as well. The analysis results show that the strength matching factor affects J-integral value greatly, that is, low matching of inhomogeneous welded joint of same steel can help to improve the ductility of the welded joint and the influence of the matching performance of dissimilar steel welded joint is more complex.

ZnO sheets have been synthesized via microwave-assisted reaction of ZnO precursor in aqueous solution using a CEM microwave system. Their morphologies, crystal structures and photocatalytic performances in the reduction of Cr(VI) were characterized using scanning electron microscopy, transmission electron microscopy, X-ray diffraction spectroscopy and UV-vis absorption spectrophotometer, respectively. Results show that ZnO sheets synthesized in 5 min time scale exhibits a optimal photocatalytic performance in the reduction of Cr(VI) with removal efficiency of 81% under UV irradiation due to the maximal intensity of light absorption and the minimal probability of electron-hole pair recombination. Published version

We systematically examined the effect of atomic undercoordination on the performance of bonds and electrons of Rb and Cs atomic clusters and their solid skins using a combination of photoelectron spectrometric analysis and density functional theory calculations. Results show that atomic coordination number reduction shortens the bonds by up to 30% for the Rb13 and Cs13 clusters, which densifies the local electrons and entraps their binding energies. Consistency between predictions and observations revealed that the Rb 4p level shifts from 13.654 eV for an isolated atom to a bulk value of 14.940 eV and the Cs 5p level shifts from 10.284 to 11.830 eV upon bulk formation. Such core–electron densification and entrapment polarize the valence charge from the inner to the outermost layer of skins, which perturbs the local Hamiltonian and hence dictates the unusual behavior of the Rb and Cs solid skins and nanocrystals.

By using nonequilibrium Green’s functions in combination with the density functional theory, we investigate the electronic transport properties of edge hydrogenated zigzag-edged graphene nanoribbon heterojunctions. Results show that a perfect spin-filtering effect with 100% spin polarization and a rectifying behavior with a ratio larger than 105 can be realized by dihydrogenation, which can also be modulated by changing the widths of the two component ribbons.

From the perspectives of the energy band theory, the bond order-length-strength correlation, the local-bond-averaging approach, and the core–shell configuration for nanostructures, we have reconcil...

Correlation between the elastic and the vibronic behavior of TiO 2 and their responses to the variation of crystal size, applied pressure, and measuring temperature has been investigated based on the bond order–length-strength correlation mechanism. Theoretical reproduction of the measurements clarified that: (i) the elastic modulus (B) and the Raman shifts (Δω) are strongly correlated and we can know either one of the B or the Δω from the other; (ii) the under-coordination induced cohesive energy loss and the energy density gain in the surface up to skin depth determines the size effect; (iii) bond expansion and bond weakening due to thermal vibration originates the thermally softened elastic modulus and the Raman shifts; and (iv) bond compression and bond strengthening results in the mechanically stiffened elastic modulus and the Raman shifts. With the developed premise, one can predict the changing trends of the concerned properties with derivatives of quantitative information of the atomic cohesive energy, binding energy density, Debye temperature, and nonlinear compressibility of the specimen.

Using a combination of the bond order–length–strength correlation theory, the spin-polarized tight binding method, the first-principles calculations, and the atomistic photoelectron distillation experiments, we investigated the mechanisms of edge-selective generation and hydrogenated modulation of Dirac-Fermi polarons (DFPs) surrounding the atomic vacancies at a graphite surface and at the edges of graphene nanoribbons (GNR). We found that: (i) the DFPs with a high-spin density at a zigzag-GNR edge and at an atomic vacancy result from the isolation and polarization of the dangling σ-bond electrons of √3d (d is the C–C bond length) distance along the edge by the locally and densely entrapped bonding electrons; (ii) along an armchair-GNR edge and a reconstructed-zigzag-GNR edge, however, the formation of quasi-triple-bond between the nearest edge atoms of d distance prevents the DFPs from generation; and (iii) hydrogenation reduces the spin density substantially and turns the asymmetric dumb-bell-like density into the spherical-like pz density. A further C 1s photoelectron spectroscopic purification has confirmed that the generation of the DFPs is associated with two extra peaks of energy states located at the bottom and the top edge of the C 1s band.

War-broken parts can be repaired quickly without electricity and gas in the wild by use of the thermit welding technology, so it is of great significance to study on welded quality of thermit welding parts for its military application. As the crack resistance of welded parts is an important target to estimate the welded performance, crack resistance test and microstructure analysis have been conducted on test specimens made of Q235 welded parts. Results showed that as the crack ratio was less than 20% in the Y-groove crack test, the crack propagation would not occur in the practical welding structure and that the crack resistance of welded joints could meet the welded demand.

Pump-power tunable white upconversion (UC) emission under the excitation of a 980 nm laser diode from lanthanide-doped hexagonal NaYF4 nanorods synthesized by a hydrothermal method is reported. The calculated color coordinates reveal that the UC white color output from both the Yb3+–Ho3+–Tm3+ and Yb3+–Er3+–Tm3+ triply-doped systems can be fine-tuned for a wide range of pump-power densities, but each has its own superiority. The former has a broader response scope to pump-power densities for white emission and the simulated white color output can be tuned more precisely, whereas the latter has a much broader range of white color output under the same pump-power densities. These desirable properties make these Ln3+ doped hexagonal NaYF4 nanostructures promising in applications such as miniaturized solid-state light sources, multicolor three-dimensional display devices, optical processing sensors and multicolor labels for bioprobe and bioimaging.

Understanding the energetic behavior of bonds and electrons localized in the surface of skin depth or within the atomic-scaled zones surrounding under- and heterocoordinated atoms such as vacancy defects and adsorbate impurities has long been pursuit of the community since the invention of scanning tunneling microscopy/spectroscopy. Such atomic scale, zone selective information is particularly important for one to control the process such as catalytic reaction, corrosion protection, growth nucleation, and quantum friction. Here we demonstrate that a simple technique of the photoelectron residual spectroscopy (PRS) can readily reveal such information from the Re(0001) and the Re(1231) surfaces with and without oxygen chemisorption, for instance. Under the guidelines of the BOLS-incorporated tight-binding theory, we have decomposed the photoelectron spectra with derivatives of the Re 4f5/2 binding energy of 40.015 ± 0.004 eV for an isolated Re atom and its bulk shift of 2.629 eV and the effective coordinat...

BeW is an important medium for radiation protection in the International Thermonuclear Experimental Reactor (ITER) devices. However, the mechanism for the radiation-protection ability of BeW remains unclear. An extension of the BOLS correlation mechanism [12] into the X-ray photoelectron spectroscopy (XPS) has enabled us to examine the energy and charge distribution of the specimen and clarify that the Be 1s and W 4f 7/2 energy levels undergo an elevation by 0.136 and 0.184 times those of the respective bulk constituents standing alone up-on BeW compound formation associated with polarization of the valence density of states. It is suggested that the interface potential barrier creation due to bond order distortion and bond nature alteration perturbs essentially the Hamiltonian and hence leads to the binding energy shifts. The established interface potential barrier and the polarized charge may screen the nuclear irradiation in the thermonuclear fusion devices. Findings may provide guideline for searching materials for such purpose.

In this paper, three types of titanium dioxide structures (anatase, heated amorphous and amorphous) from peroxo titanium complex were deposited on glass and wafer substrates by spraying technique. Influences of crystal structure, morphology and sodium ion on UV induced hydrophilicity were studied. X-ray diffraction revealed that crystalline anatase coatings are extremely hydrophilic (

The effect of crystal size, pressure, temperature, and their coupling on the bandgap (EG) of ZnO crystals have been investigated based on the Hamiltonian perturbation, using the extended BOLS corre...

Shrinking the size of a solid down to nanometer scale is indeed fascinating, which makes all the otherwise constant physical quantities to be tunable such as the Young’s modulus, dielectric constant, melting point, etc. The variation of size also generates novel properties that can hardly be seen in the bulk such as the conductor-insulator and nonmagnetic-magnetic transition of noble metals at the nanoscale. Although the physics of materials at the nanoscale has been extensively investigated, the laws governing the energetic and dynamic behavior of electrons at such a scale and their consequences on the tunable physical properties of nanostructures have not been well understood [C. Q. Sun, Prog Solid State Chem 35, 1-159 (2007); Prog Mater Sci 54, 179-307 (2009)]. The objective of the contribution is to update the recent progress in dealing with the coordination-resolved energetic and dynamic behavior of bonds in the low-dimensional systems with consideration of the joint effect of temperature and pressure. It is shown that the broken-bond-induced local strain and the associated charge and energy quantum trapping at the defect sites perturbs the atomic cohesive energy, electroaffinity, the Hamiltonian and the associated properties of entities ranging from point defects, surfaces, nanocavities and nanostructures. Application of the theories to observations has led to consistent understanding of the behavior of nanometer-sized materials and the interdependence of these entities as well as the means of determining the bond energy through the temperature-dependent measurements.

An in situ X-ray photoelectron emission investigation revealed that the size trend of the 2p 3/2 binding-energy shift (BES) of Ni nanoclusters grown on SiO 2 substrate follows the prediction of the bond order–length–strength (BOLS) correlation theory [30] . Theoretical reproduction of the measurements turns out that the 2p 3/2 binding energy of an isolated Ni atom is 850.51 eV and its intrinsic bulk shift is 2.70 eV. Findings confirmed that the skin-depth local strain and potential well quantum trapping induced by the shorter and stronger bonds between under-coordinated surface atoms provide perturbation to the Hamiltonian and hence dominate the size dependent BES.

It is impossible to directly measure the photoelectron spectrum of an atom using conventional XPS due to its low detection sensitivity. In this work, an indirect method has been developed to determine the binding energy (BE) of an atom. In this method, the BE of the atom can be obtained by extrapolation of the experimental BE curves with atomic deposition coverage to zero coverage. With this method, the Ni 2p3/2 BE's of atomic Ni on TiO2(001) and (110) surfaces are deduced to be 853.69 and 853.55 eV, respectively. Compared with atomic Ni in gas phase, relaxation shifts of 7.34 and 7.48 eV are obtained on TiO2(001) and (110) surfaces, respectively. These values are very close to the relaxation shift of 7.3 eV due to d electron screening, indicating d-like screening effects from the TiO2 substrates after Ni 2p photoionization. This method is also used to determinate the Ni 2p3/2 BE's of atomic Ni on TiO2(001) with different surface stoichiometries. The difference of Ni 2p3/2 BE is due to different interfacial charge transfer. Copyright © 2010 John Wiley & Sons, Ltd.