Shell Electron Excitation Research Articles

General oscillation strength of core–shell electron excitation by fast electrons based on Dirac solutions

General oscillation strength of core–shell electron excitation by fast electrons based on Dirac solutions

DFT calculation of core– and valence–shell electron excitation and ionization energies of 2,1,3-benzothiadiazole C6H4SN2, 1,3,2,4-benzodithiadiazine C6H4S2N2, and 1,3,5,2,4-benzotrithiadiazepine C6H4S3N2

The vertical core– and valence–shell electron excitation and ionization energies of the three title molecules, 1–3, were calculated by density functional theory (DFT) using adequate functional for each type of processes and atoms under study. The inner shells treated were C1s, N1s, S1s, S2s, S2p. Molecular geometry was optimized by DFT B3LYP/6-311+(d,p). The basis set of triple zeta plus polarization (TZP) Slater-type orbitals was employed for DFT calculations. The ΔSCF method was used to calculate ionization energies. The average absolute deviation (AAD) from experiment of 26 valence-electron ionization energies calculated by DFT for the three molecules 1–3 was 0.14eV; while that of 24 calculated core-electron binding energies (CEBEs) from experiment was 0.4eV. Selected core excitation energies were calculated by the multiplet approximation for the three molecules. The AAD of twelve calculated core excitation energies by the multiplet approximation that exclude S2s cases was 0.56eV. Time-dependent DFT (TDDFT) was employed to calculate the excitation energies and corresponding oscillator strengths of core- and valence-electrons of the molecules. Some selected occupied core orbitals were used to calculate the core-excitation energies with the TDDFT (Sterner–Frozoni–Simone scheme). The core excitation energies thus calculated were in an average error of ca. 28eV compared to observed values. They were shifted to the value calculated by the multiplet approximation. Convoluted spectra based upon the shifted energies and accompanying oscillator strengths reproduce low-energy region of observed spectra reasonably well, whereas they deviate from experiment in high-energy region. Reasonable agreement between theory and experiment was obtained for the valence electron excitations of the molecules.

Revised and extended analysis of doubly ionized tin: Sn III

A spectral analysis of doubly ionized tin (Sn III) has been carried out with the help of spectra photographed on a 3 m normal incidence vacuum spectrograph of the Antigonish laboratory (Canada) using a triggered spark light source. The ground configuration of Sn III is 4d105s2. The outer and inner shell electron excitation involves configurations of the type 4d105snℓ and 4d95s2 (4f + 5p), respectively. Further excitation leads to 4d105p2 as well as 4d105p (5d + 6s) configurations. The levels of low excitations reported earlier are confirmed in this paper except for 5s7s 1S0. Six new configurations, 5p5d, 5p6s, 5snp (n = 7, 8) and 5snf (n = 5, 6), are added. In addition to that, the missing 1S0 level in 5p2 and 5sns (n = 8, 9) configurations have also been found. The analysis is supported by Hartree–Fock and least-squares fitted parametric calculations with configuration interactions. On the basis of the identifications of 264 lines, 85 levels have been established in this spectrum out of which 43 are new. The ionization energy was determined to be 246 047.3 ± 25.0 cm−1 (30.505 98 ± 0.003 10 eV).

Site specific photochemical reaction of PMMA and related polymers by inner shell electron excitation

The photoion desorption by inner shell electron excitation from solid films of poly(methyl methacrylate), poly(methyl acrylate) and poly(methacrylic acid) was studied. The assignment of the features observed in the absorption spectrum of PMMA was elucidated by a systematic comparison of the H + yield spectra of the three polymers. Detailed information about the specific excitations that promote the desorption of CH 3 + ions was obtained both in the carbon and oxygen K-edge regions. It was observed that most of the PMMA CH 3 + ions are desorbed by the fragmentation at the side chain.

Photon energy dependence of synchrotron radiation induced growth suppression and initiation in Al chemical vapor deposition

The influence of synchrotron radiation (SR) irradiation on Al chemical vapor deposition has been studied as a function of SR photon energy. A clear difference between inner shell electron excitation and valence electron excitation is observed. Suppression of Al growth on the Si surface is found to be induced effectively by the excitation of the inner shell electrons, while initiation of the growth on the SiO 2 surface is caused by the excitation of the valence electrons.

EXELFS Studies of Carbon Fibers

The present developments of electron energy analysis in the microscopes by E.E.L.S. allow an accurate recording of the spectra and of their different complex structures associated with the inner shell electron excitation by the incident electrons (1). Among these structures, the Extended Energy Loss Fine Structures (EXELFS) are of particular interest. They are equivalent to the well known EXAFS oscillations in X-ray absorption spectroscopy. Due to the EELS characteristic, the Fourier analysis of EXELFS oscillations appears as a promising technique for the characterization of composite materials, the major constituents of which are low Z elements. Using EXELFS, we have developed a microstructural study of carbon fibers. This analysis concerns the carbon K edge, which appears in the spectra at 285 eV. The purpose of the paper is to compare the local short range order, determined by this way in the case of Courtauld HTS and P100 ex-polyacrylonitrile carbon fibers, which are high tensile strength (HTS) and high modulus (HM) fibers respectively.

Monte Carlo direct simulation of low energy electron scattering in solids

The scattering of 0.1–3keV electrons in a copper target has been simulated by a Monte Carlo direct method. A partial wave method of combining the Hartree approximation with the Hartree-Fock approximation for calculation of phase shift has been used for calculating elastic scattering cross-section in the keV-energy region. The Gryzniski, Streitwolf and Quinn excitation functions are adopted to describe the shell electron excitation, conduction electron excitation and plasma excitation respectively. A method which can save memory capacity and simplify the calculation procedure is suggested to calculate average binding energy. The calculated results on the backscattering coefficient and secondary electron yield are compared with the experimental results of Shimizu.

Electron spectroscopic studies on FeNi alloys using ionization loss spectroscopy (ILS), Auger electron spectroscopy (AES) and elastic peak electron spectroscopy (EPES)

FeNi alloys have been studied by electron spectroscopy varying the sampling depth of analysis with the primary energy of ILS and comparing it to AES. An on-line computer operated CMA analyzer was used at 2 and 3 keV primary energy. AES and ILS were based on LMM transitions and 2 p 3 2 shell electron excitation respectively of both Fe and Ni. Inelastic loss peaks were evaluated taking into account single elastic scattering. A simple formula is deduced containing Reimer's elastic cross sections. The electron IMFP needed for AES and ILS was determined by EPES. New IMFP values for FeNi alloys are presented. Quantitative analysis by ILS and AES provided reasonable agreement.

The correlation between electron transmission and inner shell electron excitation spectra

Shape resonances are prominent features observed in both electron transmission spectroscopy (ETS) and inner shell electron energy loss spectroscopy (ISEELS) or x-ray absorption spectroscopy (XAS). For the inner shell excitation process the resonant state is stabilized by the positive core created. In comparing analogous features in ET and ISEEL spectra, a measure of this stabilization is given by the sum of the attachment energy from ETS and term value from ISEELS. Employing ETS and ISEELS data from the literature as well as new spectra, it is shown that within an homologous series (such as halobenzenes, vinyl halides, or methyl halides) this stabilization is nearly constant with a value in the 6 to 8 eV range. Furthermore, the intensities of shape resonances in ETS are shown to be related to intensities in ISEELS.

Scattering-angle dependence of signal/background ratio of inner shell electron excitation in EEELS

Scattering-angle dependence of signal/background ratio of inner shell electron excitation in EEELS

Electron excitation and capture inF8+plus Ne collisions

$K$ x-ray spectra from the nearly symmetric collision system ${\mathrm{F}}^{8+}$ plus Ne were obtained over the bombarding energy range from 10 to 40 MeV with sufficient spectral resolution to observe separately the $K$ x-ray transitions from states formed by $K$-shell electron excitation and electron capture to excited states of fluorine. The cross sections for the two processes were obtained by normalization to total $K$ x-ray production cross sections. The $K$ x-ray production cross section for electron capture to excited states falls off by a factor of 40 over the energy range of 10 to 40 MeV, and the $K$-shell electron excitation cross section increases by a factor of 4 over the energy range 20 to 40 MeV. The $K$-shell excitation cross section has an energy dependence quite different from that observed for the asymmetric systems.

X-ray production by electron excitation, ionization, and capture forFq+(q=1−9) ions in collisions with a He gas target

$K$ x-ray transitions resulting from collisions between F projectiles, with charge states ranging from ${1}^{+}$ to ${9}^{+}$, and He atoms have been observed. Production mechanisms leading to projectile $K$ x rays include $K$-shell electron excitation, single $K$-shell multiple $L$-shell vacancy production, and electron capture. The measured F $K$ x-ray production cross sections range from ${10}^{\ensuremath{-}22}$ ${\mathrm{cm}}^{2}$ for low charge states to ${10}^{\ensuremath{-}17}$ ${\mathrm{cm}}^{2}$ for incident bare ions. Using calculated average fluorescence yields, the $K$-shell electron excitation, single $K$-shell, single $K$-shell + single $L$-shell, single $K$-shell + double $L$-shell ionization, and electron-capture cross sections have been determined. The measured ionization cross sections are found to decrease with the increase in projectile charge state, whereas single-$K$-shell electron-excitation cross sections increase with the increase in projectile charge state.

Electron Interaction Cross Sections in Al and Al2O3; Calculations of Mean Free Paths, Stopping Powers, and Electron Slowing-Down Spectra

The prospects for obtaining better theoretical calculations of experimentally interesting electron interaction effects, over a wide range of electron energies, are now considerably improved through the development of models for valence electron excitation in simple insulators and through the availability of theoretical atomic generalized oscillator strengths for inner shell electron excitation in several low-Z atomic systems. We describe briefly the way in which this information may be used to calculate mean free paths, stopping powers, and electron slowing-down spectra in Al metal and the insulator Al2O3.

Optically Observed Inner Shell Electron Excitation in Neutral Kr And Xe

Received 23 December 1963DOI:https://doi.org/10.1103/PhysRevLett.12.106©1964 American Physical Society