Estimation of backscattering factor for low atomic number elements and their alloys

The single elastic scattering theory of Everhart was adapted to determine the angular and energy distribution of electrons backscattered from low atomic number solid materials (Z < 40–45). This distribution and the classical ionization cross-section expression of Gryziński were used in the calculations of the backscattering factor, r, in quantitative AES analysis. The values of r were found to be in reasonable agreement with the results of the Monte Carlo calculations and the existing experimental data. Everhart's theory was extended for the case of mixtures, and that made possible the determination of the backscattering factor for binary alloys. It was found that neglecting the concentration dependence of r in quantitative AES analysis apparently enriches the surface with the component having the lower atomic number. The experimental data on surface composition of binary alloys measured by AES are discussed in view of the presented theory.     

High resolutionLMM Auger spectra of low energy from solid surfaces

LMM Auger spectra of Cl, K, Ca, Cr, Mn, Fe, Co, Ni, Cu, and Zn have been investigated with an electrostatic cylindrical spectrometer with energy resolution of about 0.05% in the energy range of 100 eV–1 keV. The Auger electrons have been excited by 5 keV electron bombardment at a grazing incidence angle and the peak of elastically scattered primary electrons have been used for calibration. The line assignments have been discussed.     

Hyperfine magnetic anomaly in the atomic spectra of rare-earth elements

Hyperfine-splitting constants in the optical spectra of rare-earth elements, Nd, Eu, Gd, and Lu, were measured using the laser-induced resonance fluorescence in a low-divergence atomic beam. Values of the hyperfine magnetic anomaly for different atomic levels were determined by comparing the ratios of the magnetic dipole constants of neighboring isotopes with odd numbers of protons or neutrons. The relation of these values to the special features of the atomic and nuclear structure of the investigated elements is discussed.     

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.     

The Auger spectra of uranium

TheL, M, andK-Auger andL-Coster-Kronig spectra of uranium were measured and are compared to other experimental and theoretical work. The meanL-shell fluorescence yield of uranium was measured as \(\bar \omega _L \) =0.53±0.06.      

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.     

Disorder broadening of alloy Auger spectra

Auger spectroscopy promises the means to separate initial and final state contributions to the disorder broadening of core XPS spectra in disordered alloys. Auger disorder broadening, deduced from recent ab initio results, is predicted to be greater than XPS disorder broadening for Cu₅₀Pd₅₀ and Ag₅₀Pd₅₀ alloys. Simulations are used to assess whether this effect is observable experimentally despite the greater lifetime broadening of Auger spectra. A number of cases where narrow core–core–core Auger transitions should allow clear experimental identification of this effect are identified. The prospects for determining environment-resolved Auger spectra using APECS have been investigated.     

Solid-state and atomic features in the valence-band Auger spectra of copper,silver, and gold

High-resolution measurements of the L₃VV, M₄₅VV, and N₆₇VV Auger spectra are reported for copper, silver, and gold, respectively. Qualitative trends in the spectra and experimentally determined values of U_eff/2W (U_eff is the effective energy required to excite two holes on the same atom; W is the d-electron bandwidth) are shown to be consistent with recent predictions by Sawatzky and Cini concerning the relative importance of atomiclike and bandlike features in Auger spectra.     

TheL- andK- Auger spectra of tellurium

TheL- andK- Auger spectra of tellurium (Z=52) were studied from the electron capture decay of¹²⁵I. The measured relativeL- Auger transition intensities are not in agreement with the theoretical intensities of Asaad for silver (Z=47). The measured relativeKLL intensities are in agreement with those ofGraham et al. Relative intensities are given for theKL Y spectrum. TheKL Y/KLL ratio was measured to be 0.44 ± 0.02 in good agreement with the theoretical value given byWapstra.K/L andL subshell conversion ratios are given for the 35 keV nuclear transition in¹²⁵Te.     

Solid state broadening in Auger spectra

Some Auger spectra in the gas phase show extremely sharp lines and a great deal of fine structure while the Auger spectra of solids, even at high resolution, lack this detailed fine structure and generally have much broader peaks. In an effort to understand the broadening processes which occur on condensation of a gas or vapour to the solid phase, several solids for which high resolution gas phase data exists have been studied. The result of measurements of the M₄₅N₄₅N₄₅ Auger spectrum of cadmium are reported and comparison is made with the vapour phase data. Although the solid data contains considerable quasi-atomic fine structure the lines are broader than the vapour phase and by matching computer broadened vapour phase data to the experimental data an estimate of the individual line widths may be made. The relative intensities of the lines in the simulation agree closely with the solid data if loss processes are considered. Measurements have also been made on the same Cd transition in CdS and in this material the Auger lines are much broader than in Cd metal and the fine structure has almost disappeared. Results are also reported of measurements of the Auger spectra of solid rare gases made with the aid of a UHV cryostat capable of operating at temperatures down to 10 K. The gases studied were Xe, Ar and Kr and again comparison with computer broadened gas data enable the broadening of individual Auger lines to be estimated. Measurements of the line breadths have been made at various temperatures and the results of these experiments will be discussed in terms of lifetime and lattice vibrational broadening.     

Auger electron spectra of gaseous halogen compounds

Auger CW and Coster-Kronig spectra in gas phase of boron trifluoride, boron trichloride, boron tribromide and hydrogen bromide have been obtained by 2 keV electron impact. The fluorine spectrum can be understood as quasi-atomic by the Thomas—Weightman Δ U/W criterion, while in the spectra of the heavier halides some of the final states are delocalized. The boron spectrum from boron trifluoride is definitely band-like, but it also shows two prominent quasi-atomic structures induced by fluorine. A simplified model allows the nature of these “partner resonances” to be understood and their intensities calculated; a semi-quantitative agreement with experiment is obtained without adjustable parameters. We provide evidence that these resonances are a general feature of the CW spectra of ionic molecules and identify them in the boron spectrum, from boron tribromide, as well as in the literature data.     

Determinations of low atomic number elements in real uranium oxide samples using vacuum chamber total reflection x‐ray fluorescence

Conditions for the total reflection x‐ray fluorescence (TXRF) analysis of real uranium samples for low atomic number elements using vacuum chamber TXRF spectrometer were optimized. It was observed that for analysis of low atomic number elements, almost complete removal of uranium matrix is required. Two certified reference materials of uranium containing trace elements in different concentrations were dissolved in minimum amount of high purity nitric acid. The uranium matrix from these solutions was separated by solvent extraction using tri‐n‐butyl phosphate as extracting reagent. Low atomic number elements in TXRF spectrum of the aqueous phase could be seen only after six tri‐n‐butyl phosphate equilibrations in extraction. The TXRF determinations of the certified low atomic number elements Mg and Al were made in these aqueous solutions after addition of Sc as an internal standard. The TXRF determined values for Mg were in good agreement with the certified values, whereas TXRF determined Al values differed from the certified values appreciably, probably due to the interference of Al Kα peak with escape peak of U Mα and the neighboring Si Kα peak. Copyright © 2013 John Wiley & Sons, Ltd.     

Auger and emission spectra of carbon nanotubes

The Auger and x-ray emission spectra of carbon nanotubes are calculated by the FP-LMTO method. The computed spectra for nanotubes are compared to the analogous spectra for a graphite monolayer, which is used as a test object, and to the experimental curves for graphite. It is concluded that the Auger-characteristic emission can be used to identify carbon nanotubes. Fiz. Tverd. Tela (St. Petersburg) 41, 1511–1514 (August 1999)     

Resonant Auger spectra of open shell rubidium atom

Resonant Auger electron spectra of atomic rubidium have been measured using selected photon energies to excite the 3d electrons to 5p Rydberg orbitals. The structures of the spectra were investigated by comparing the observed intensity distributions with the results of multiconfiguration Dirac-Fock calculations. The theoretical profiles were calculated taking into account the population of the initial states.     

Radiative Auger emission in Ne K X-ray spectra

Radiative Auger emission intensity in K X-rays from neon was measured following electron bombardment by 1 to 2 keV electrons. The measured relative intensities of this process are in good agreement with calculations of Dyall using correlated final-state wavefunctions.     

Excitation lines and multiple ionization in Auger spectra

Satellite lines of a new type and excessively large continuous distributions of energy degraded electrons are observed in theKLL Auger spectra of potassium, chlorine, and sulfur. The lines are tentatively interpreted as due to a process that is characteristic of the atom more than of the entire solid and the excessive number of electrons in the continuous distributions is interpreted as due to multiple ionization.     

Energy parameter and the free-atom behavior of Auger spectra

The L₃M₄₅M₄₅ spectra of V and Cr do not exhibit free atom behavior, in sharp contrast to those of Cu and Zn. An energy difference parameter, Δ ?, derived entirely from observable energies, has been introduced to correlate with the extent of electron localization and free-atom behavior in Auger transitions.