Correlation between Mössbauer isomer shifts and XPS binding energies

A series of low-spin pentacyanoferrates (‖) of the type Na₃[Fe-(CN)₅L] (L = phosphine or phosphite) have been characterized by⁵⁷Fe Mössbauer spectroscopy and X-ray photoelectron spectroscopy. The Fe?P bond in Na₃[Fe(CN)₅L] is discussed in terms of a correlation between the isomer shift and the binding energy. It has been demonstrated that the isomer shift increases with the decreasing Fe2p_3/2 binding energy. The Mössbauer isomer shift reflects the total electron density at the nuclear site, while the chemical shift in the binding energy is concerned with the electron density on the atom of interest. The increasing Fe-to-P back donation leads to an increase of the s-electron density at the iron nucleus, i.e. a decrease of the isomer shift. The increasing tendency in the Fe2p_3/7 binding energy is interpreted by the increasing Fe-to-P back donation.     

Reference energies for inner shell electron energy-loss spectroscopy

The energies of a number of selected inner shell atomic and molecular electronic transitions in the energy range 100–1000eV have been carefully remeasured for energy scale calibration in electron energy loss Spectroscopy. The measurements have been made using an inner shell electron energy loss spectrometer in conjunction with a digital voltmeter of high accuracy.     

On the calculation of inner shell ionization energies and E.S.C.A. shifts

In the calculation of inner-shell ionization potentials, the Koopmans theorem is unsatisfactory owing to a large ‘relaxation’ of the valence electron distribution, following the creation of an inner-shell ‘hole’. The effects of this relaxation are studied, using a group-function formulation to analyse the energy into core and valence contributions. Applications to the lithium atom and the methane molecule indicate that relaxation effects can be large. The importance of these results in the interpretation of E.S.C.A. data is discussed.     

A comment on shell corrections to nuclear binding energies

An elementary method to correct the semi-classical evaluation of nuclear masses for shell effects in presented and compared with other approaches.     

Second order binding energies and spectra with an interaction matrix deduced from phase shifts

The matrix elements deduced from phase shifts in an earlier paper are modified to incorporate the effects of a hard core and then used in second order perturbation theory to calculate binding energies and spectra for some light nuclei near closed shells.     

Total cross sections for charge transfer reactions of protons with atomic and molecular targets at high projectile energies: The role of inner orbitals

The single capture total cross section (TCS) for scattering of high energy protons from some noble gases and small molecules is calculated by using the full plane wave first Born approximation (PWFBA). It is shown that even deep subshells have a noticeable contribution to the resulting TCS. We also find that the exchange mechanism which can also be incorporated in the PWFBA gives rise to a small effect on TCS for all the investigated targets.     

Radiative charge transfer and radiative association of protons colliding with Na at low energies

Using the fully quantum-mechanical approach, the radiative charge transfer for H⁺ + Na(3s) collisions has been investigated. The charge transfer emission spectra are analyzed at resonant and non-resonant collision energies. The radiative association cross sections, obtained by subtracting the radiative charge transfer part from total radiative decay cross sections calculated by the optical potential method, are presented in the energy range 10⁻⁶-1 eV.     

Correlation between impurity binding energies and heat of formation of alloys

We survey recent hyperfine-interaction measurements of the binding energies E_B between two different impurities in dilute ternary alloys of iron, copper, silver and gold. The binding energies are related to the heat of formation of the corresponding alloys. A significant correlation between these two quantities is found.     

Relationship between charge transfer energies of Yb and Sm and crystal environmental factor

Relationship between charge transfer energies E_CT of Yb³⁺ and Sm³⁺ and environmental factors h_e in various crystals was investigated using a dielectric chemical bond method. Both results show that they have an exponential relation E_CT=A+B exp(−kh_e), but the exponential factors are different, which indicates that the interaction between the rare earth ions and environment is connected with the kind of rare earth ion. This result provides a method of determining charge transfer energies of Yb³⁺ and Sm³⁺ from a crystal structure.     

Correlation effects in pion double charge exchange in the f72 shell

Analog and non-analog transitions have been measured in the reactions ⁴⁸Ca(π⁺, π⁻)⁴⁸Ti and ⁴⁸Ti(π⁺, π⁻)⁴⁸ Cr at pion energies of 130, 180, 235, and 292 MeV, and θ=5°. The ratios of cross sections for the different transitions are discussed in terms of different models of DCX which offer contrasting explanations.     

Interpretation of charge transfer bands in Fe doped SrTiO3 crystals

The electronic structures of SrTiO₃ crystals doped with Fe³⁺, Fe⁴⁺ and Fe⁵⁺ ions have been investigated using the Xα cluster approach. The ground-state eigenvalues show the lower Fe acceptor level, of t_2g↓ symmetry, localized inside the SrTiO₃ band gap, respectively at 2.8 eV $\text{(}\text{Fe}{}^{\mathrm{3+}}\text{, S =}\text{5}\text{2}\text{), 1.6}\text{eV}\text{(}\text{Fe}{}^{\mathrm{4+}}\text{, S = 1)}\text{or}\text{1.1}\text{eV}\text{(}\text{Fe}{}^{\mathrm{4+}}\text{, S = 0)}\text{and}\text{1.1}\text{eV}\text{(}\text{Fe}{}^{\mathrm{5+}}\text{, S =}\text{3}\text{2}\text{)}$ above the valence band edge. Other acceptor levels, with eg↓ and eg↑ symmetries, appear inside the gap when the Fe nominal ionicity increases.The theoretical Xα excitation energies of O 2p-Fe 3d transitions confirms the experimental interpretations of acceptor charge transfer bands for the optical absorption spectra of SrTiO₃:Fe⁴⁺ and SrTiO₃:Fe⁵⁺ crystals.The large optical excitation energies compared with the thermal transitions are partly due to the O 2p band width.     

Accurate core binding energies of ions from Dirac-Fock calculations combined with experimental atomic binding energies

Core binding energies are reported for the singly-charged alkali ions obtained by removing the outer s electron and for the singly-charged halide ions obtained by adding a P_{$\text{3}\text{2}$} electron. The levels studied are Li 1s, Na 1s, K 2p, Rb 3p, Cs 3d, F 1s, Cl 2p, Br 3p and I 3d. The binding energies were obtained by combining DiracF?ock ΔSCF binding-energy shifts between the ions and the corresponding isoelectronic rare gases with experimental rare-gas binding energies, and also by combining the calculated atomīon shifts with experimental atomic binding energies where available. It is shown that the former approach corrects accurately for the correlation energy, which is not included in single-configuration calculations.     

Mechanisms responsible for chemical shifts of core-level binding energies and their relationship to chemical bonding

A comprehensive review of different mechanisms which contribute to the chemical shifts of core-level binding energies, BEs, is made. A principle focus is on showing how the mechanisms can be used to relate the BE shifts to features of the chemical bonding and chemical interactions in the studied system. Several initial state mechanisms are identified; while some are well known, the importance of others has been only recognized fairly recently. A theoretical framework is presented which places the analysis and interpretation of these BE shifts on a firm foundation. A rigorous definition and distinction of initial and final state effects is presented. This definition is applied to show that initial state effects are often the dominant factors for the chemical BE shifts. It is also shown that, in many cases, theoretical approaches involving the use of constrained variations can permit a clear and definitive separation of the contributions of the different mechanisms. Several representative applications to the analysis and interpretation of core-level BE shifts are described which show how the theoretical methods of analysis can be used to identify the mechanisms important for the BE shifts. Often more than one mechanism makes an important contribution to the shifts and it is common that the contributions will be canceling. When all of the relevant mechanisms are taken into account in the analysis of the BE shifts, these shifts do provide valuable information about the chemical bonding and electronic structure of the materials being studied. The mechanisms presented and the theoretical frameworks described provide a unified view of BE chemical shifts.     

A note on the projectile charge dependence of inner shell ionisation of atoms by heavy charged particles

The formula for the binding of the electron to the impinging projectile in inner shell ionization of atoms by heavy charged particles in the static approximation, are generalized to arbitrary electron wavefunctions. The effect is calculated for K-shell electrons using relativistic wavefunctions. A qualitative difference in the impact parameter dependency of the effect between light and heavy target are found.     

Electronic structure of a complex with charge transfer and carrier energy bands in thin films of semiconductors containing carbazole

The electronic structures of hole and electron carrier energy bands and complexes with charge transfer (CCT) in films of semiconductors containing carbazole and sensitized with TNP were determined by the methods of photoelectron and electron spectroscopy as well as by studying the wavelength dependence of the quantum yield of photogeneration at temperatures of 295 and 80 K. The hole carrier bands are determined by the top three filled electronic levels of the carbazole nuclei, while the electron carrier bands are determined by the bottom free electron level of TNP. The first three excited states of CCT are determined, respectively, by electronic transitions from the first three top filled electron levels of the carbazole nuclei to the bottom free electronic level of TNP. Photogeneration of current carriers is observed with excitation of CCT in the region of the second and third electronic transitions.Translated from Izvestiya Vysshykh Uchebnykh Zavedenii, Fizika, No. 7, pp. 47–51, July, 1989.     

Isotopic dependence of the nuclear charge radii and binding energies in the relativistic Hartree-Fock formalism

Relativistic nonlinear models based on the Hartree and Hartree-Fock approximations, including the σ, ω, π, and ρ mesons, are worked out to explore the behavior of the nuclear charge radii and the binding energies of several isotopic chains. We find a correlation between the magnitude of the anomalous kink effect (KE) in the Pb isotopic family and the compressibility modulus (K) of nuclear matter. The KE appears to be sensitive, in particular, to the mechanisms which control the K value. The influence of the symmetry energy on the Ca isotopic chain is also studied. The behavior of the charge radii of single-particle states for some special cases and its repercussion on the nuclear charge radius is analyzed. The effect of pairing correlations on the models improves considerably the quality of the results in both binding energy and KE.     

Correlation between charge transfer and stick-slip friction at a metal-insulator interface

Techniques have been developed that facilitate the measurement and imaging of the charge exchanged between metal-insulator surfaces in relative motion. In the regime where the forces of friction lead to stick-slip motion, we find that the charge transfer accompanying the slip events is proportional to the force jumps and is bunched at the stick locations. The constant of proportionality is measured in electron volts per angstrom and has a small variance over a large range of slip sizes, suggesting that in these experiments macroscopic friction originates from and scales to the intrinsic electronic interactions that form between metal and insulator surfaces.