Bremsstrahlung-induced Auger transitions and photoemission in elemental red phosphorus

Measurements of the Bremsstrahlung-inducedK-LL andK-LM Auger transitions in red phosphorus are reported and compared with semi-empirical data. The relative intensities of theK-LL lines are in excellent agreement with predictions based on the intermediate coupling scheme including configuration interaction. There is, however, a disagreement between the predicted and the experimental values of the kinetic energies. The origin of this discrepancy is due to inaccurate binding energy values used in earlier semiempirical estimations. Revised semi-empirical energy values based on reliable binding energies determined by internal and conventional x-ray photoemission are in excellent agreement with the experimental data. The energy of the x-rayK radiation is 2,013.8±0.4 eV, the Wagner's Auger parameter amounts to 1,987.2±0.1 eV in elemental red phosphorus, and to 1,983.9±0.5 eV in phosphorous oxide.     

Interatomic internal photoemission peaks in (Auger) electron spectra

Internal photoemission (IPE) features appearing in (Auger) electron spectra have two distinguishing properties: (1) they obey optical selection rules and (2) IPE intensities increase rapidly with incident excitation electron energy. IPE and Auger electrons from elemental materials have similar energies, giving complicated mixed spectra; however, core-level interatomic IPE peaks (from compounds) can appear by themselves, as shown here using SiO ₂. The IPE process has high photon utilization efficiency, and core interatomic IPE shows promise for certain specialized applications discussed in the text.     

The natural procedure for the auto-deconvolution of CVV-type Auger peaks

CVV-type Auger peaks may give information on the density of states of valence bands. For this, the measured Auger electron intensity curves have to be subjected to a mathematical procedure called auto-deconvolution. The generally accepted algorithm for this is the RAIZ Algorithm [7]. A theoretically equivalent but much simpler algorithm, the Natural Procedure, is proposed here. It is also shown that the Natural Procedure requires much less computational work than the RAIZ algorithm, even when compared with the improved version as presented here.     

Artificial peaks in energy dispersive X‐ray spectra: sum peaks,escape peaks,and diffraction peaks

Sum peaks, escape peaks, and diffraction peaks are considered artificial or spurious peaks in energy dispersive X‐ray spectrometry. Experimental examples are given, which showed that escape and diffraction peaks can add up to become sum peaks. These artificial peaks are not weak, and great care must be taken to differentiate them from peaks due to impurity or trace elements. The relationship between the intensity of a sum peak and the original peaks is illustrated using computer simulation as well as probability theory. Copyright © 2016 John Wiley & Sons, Ltd.     

Finding two-dimensional peaks

Two-dimensional generalization of the original peak finding algorithm suggested earlier is given. The ideology of the algorithm emerged from the well-known quantum mechanical tunneling property which enables small bodies to penetrate through narrow potential barriers. We merge this “quantum” ideology with the philosophy of Particle Swarm Optimization to get the global optimization algorithm which can be called Quantum Swarm Optimization. The functionality of the newborn algorithm is tested on some benchmark optimization problems. The text was submitted by the author in English.     

Influence of surface environment on Auger peaks : The Palladium M45N45N45 transition

The fine structure of the M₄₅N₄₅N₄₅ Palladium Auger transition was investigated. The energy of the peaks and the changes of their shapes due to surface modifications, either by alloying or by oxidation are studied. It is found that the fine structure is due to the overlapping of two “band-like” transitions of the type M₄VV and M₅VV.     

Auger spectrum of ammonia

The Auger spectrum of ammonia has been measured in the vapor phase, completing the isoelectronic series Ne, HF, H₂O, NH₃, and CH₄. Eleven transitions are possible, but three leading to triplet final states are expected to be very weak. Two others are expected on theoretical grounds to be unresolvable. The spectrum showed seven resolvable peaks, in keeping with these expectations. The peaks range in width from 2.2 to 7.4 eV, the narrowest being associated with vacancies in non-bonding lone-pairs and the broadest with vacancies in bonding orbitals. There is reasonably good agreement between the experimental results and recent theoretical calculations for both energy and intensity.     

Auger photoelectron coincidence spectroscopy

Auger photoelectron coincidence spectroscopy (APECS) is a technique that provides us with unique information and a chance to gain insight into the significance of processes in the Auger spectra of atoms in solids. Hence it is a great aid in our understanding of the Auger process in atoms where electron correlations are strong. Despite the first demonstration of the technique more than 20 years ago, there are still very few working experiments. The reasons why, and the ways forward are discussed.     

COSY with in-phase cross peaks

We have designed two pulse sequences that give rise to COSY-type spectra with in-phase multiplet structure. In these spectra, the cross peaks are absorptive and in-phase along both dimensions. Such 2D spectra are useful for quantitative measurements, such as measurement of the extent of H/D exchange in proteins and measurement of the concentrations of individual components in a series of mixtures. These spectra can also be used to emphasize cross peaks between weakly coupled protons.     

Peripheral resonances and exotic peaks

A simples-channel resonance model based on dominance of peripheral resonances is proposed. It explains the appearance of exotic peaks with slopes similar to those of forward scattering amplitudes. The interaction radiusR plays a significant role in determining the slope and dip structure.     

Beam-foil-excited Auger transitions in neon

Energy spectra of electrons ejected from collisions between a carbon foil and Ne projectiles with energies between 1.4 and 20 MeV have been measured. Continuous and discrete electron energy distributions are observed. Auger transitions of foil-excited Ne have been studied. Using relativistic Dirac-Fock multiconfiguration calculations, most of the measured Auger transitions have been identified.     

Auger spectra of lithium hydride

Auger electron emission spectra have been observed for lithium hydride in three conditions : (1) cleaved in vacuum, (2) prepared by the reaction of hydrogen gas with clean lithium metal, and (3) by annealing slightly oxidized lithium hydride single crystals in vacuum. The dominant Auger line (40 ± 1 eV) was found to be a KVV transition involving valence electrons from the anion and was indistinguishable from a similar transition for lithium oxide at room temperature. Lithium hydride surfaces lose hydrogen in vacuum causing the formation of a lithium metal phase at room temperature and a significant reduction in surface hydride stoichiometry at 600°C.     

Auger recombination of electron-hole drops

Phonon-assisted Auger recombination is calculated for indirect band gap semiconductors in the strongly degenerate case. It follows a reciprocal lifetime τ^?1=Cn² with C=7.19×10³¹ cm⁶ sec^?1 for Si and C=2.94× 10^?31 cm⁶ sec^?1 for Ge. These results are in good agreement with experimental values of the decay of electron-hole drops. Therefore one can conclude that phonon-assisted Auger recombination is the essential nonradiative recombination process in this case.     

Experimentally derived Auger transition probabilities in X-ray excited Auger electron spectroscopy (XAES)

The capability of Auger transition probabilities experimentally derived from X-ray excited Auger electron spectra in XPS were tested. The relative sensitivity factor (RSF) method has been employed in the quantification by AES (Electron excited Auger electron spectroscopy). However, the difference between experimentally derived RSF and theoretically calculated ones has been found in some reports. One of the great reason of the difference may be caused by the calculated values of the Auger transition yield which has been commonly employed without the consideration of the allotment of coupling scheme in the transition selected in the quantification, for instance, the allotment of each six coupling KL₁L₁, KL₁L₂, KL₁L₃, KL₂L₂, KL₂L₃, and KL₃L₃ in KLL transition. The employment of derived Auger transition probabilities reduce the difference between theoretically calculated RSF and experimentally derived one.     

Alloy-assisted Auger recombination in InGaN

It has been numerically investigated the effect of alloying on the Auger recombination rate in wurtzite type n-InGaN. In order to explicitly take into account the effect of alloy disorder, the calculations have been performed with a 256-atom supercell that includes In and Ga atoms randomly distributed over the supercell sites to obtain a given composition. A full band structure (no band scissors-shifting) and high-dense inhomogeneous k-point grid were used to improve the accuracy of the calculations. We show that the large number of allowed interband Auger transitions originated by the breaking of the translational periodicity plays a crucial role in the wide band gap InGaN alloys. The alloy-assisted Auger coefficients for these alloys are in the 1.0?×?10^?32–4.7?×?10^?31 cm⁶/s range     

Continuous X-ray-induced Auger electron spectroscopy

Bremsstrahlung emission from a tungsten anode has been used, for the first time, to obtain X-ray-induced Auger electron spectra (CXAES) in a conventional X-ray photoelectron spectrometer. Auger KLL signal and background intensities obtained from a silicon—aluminium sample have been compared with those obtained un der the same experimental conditions but using a standard aluminium anode. For such an aluminium anode, the respective contributions of the bremsstrahlung and the characteristic radiation to the C_KVV intensity have also been established.     

Rule of corresponding Auger spectra

The normalized core-valence-valence Auger spectra A(?) of the simple metals Be, Mg, and A$\text{l}$, when plotted as a function of ?/2λ, where λ is the free-electron Fermi energy, are all nearly the same. Li, with λ=4.1±0.1 eV, also has the same spectrum. This suggests that the Auger spectra of simple metals depend primarily on the electron gas density and are almost independent of details of the band structure.