A high sensitivity momentum dispersive multichannel electron momentum spectrometer for studies in experimental quantum chemistry

Todd, B.R.; Lermer, N.; Brion, C.E.

doi:10.1063/1.1145195

Cited by 21 publications

(4 citation statements)

References 18 publications

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“…However, a large finite cross section at low momentum has been clearly observed (Brunger et al 1994) in the Xe 4d measurement (figure 1). This phenomenon has been confirmed by a further measurement (also shown in figure 1) for Xe 4d (Zheng et al 1998) recently obtained at E = 1200 eV using a high-performance angledispersive multichannel (e, 2e) spectrometer (Todd et al 1994), under similar experimental conditions. The 'unexpected' significant 'turn up' of the cross section below p ∼ 1 au was reproduced by a distorted-wave Born approximation (DWBA) calculation (Brunger et al 1994) using a near Hartree-Fock limit basis set (Clementi and Roetti 1974).…”

Section: L224supporting

confidence: 78%

Distorted-wave effects at low momentum in binary (e, 2e) cross sections for d-orbital ionization

Brion

Zheng

Rolke

et al. 1998

J. Phys. B: At. Mol. Opt. Phys.

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Unexpected and previously unexplained behaviour showing appreciable intensity at low momenta in previously published binary (e, 2e) cross sections for ionization from nd atomic orbitals including Xe 4d, Zn 3d and Cd 4d is investigated. Similar effects have also been observed recently in binary (e, 2e) studies of metal hexacarbonyls for the least tightly bound molecular orbitals which are dominated by metal nd character. The finite cross sections at low momenta (i.e. non-nodal behaviour) are not predicted by plane-wave calculations for atomic targets, but can be accounted for using distorted-wave theory. These distortion effects at low momenta appear to be due to a high-effect and the even-parity nature of nd atomic orbitals.

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Section: L224supporting

confidence: 78%

Distorted-wave effects at low momentum in binary (e, 2e) cross sections for d-orbital ionization

Brion

Zheng

Rolke

et al. 1998

J. Phys. B: At. Mol. Opt. Phys.

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“…Thereafter, Weigold et al [10] have introduced one-dimensional position-sensitive detectors (PSDs) for parallel measurements over a range of energies. Brion et al [11] have reported a momentum dispersive spectrometer. These spectrometers are either energy or momentum dispersive and can be roughly classified as the second generation (EMS-2).…”

Section: Introductionmentioning

confidence: 99%

Improvements on the third generation of electron momentum spectrometer

et al. 2008

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The significant modifications to our recently constructed electron momentum spectrometer have been implemented. Compared with our previous report, the energy and the angle resolutions are significantly improved and reach ΔE = 0.45 eV, Δθ = ±0.53° and Δφ = ±0.84°, respectively. Moreover, the details of data reduction and the relation between azimuthal angle range and the sensitivity are discussed.

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“…These difficulties have been significantly reduced by improvements in instrumentation. Recently reported multichannel EMS spectrometers − have substantially improved the sensitivity over that of earlier single channel instruments…”

Section: Introductionmentioning

confidence: 99%

Glycine Valence Orbital Electron Densities: Comparison of Electron Momentum Spectroscopy Experiments with Hartree−Fock and Density Functional Theories

1996

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Experimental momentum profiles (orbital images) corresponding to the electron density distribution in the outer valence shell of gaseous glycine have been obtained by electron momentum spectroscopy measurements conducted over the binding energy range of 6−27 eV at an impact energy of 1200 eV + binding energy. The experimental data are compared with theoretical momentum profiles calculated using Hartree−Fock and Kohn−Sham density functional theories. The calculated momentum profiles correspond to a Boltzmann weighted sum of the five dominant conformers predicted to be present at the experimental temperature of 165 °C. The importance of basis set size and flexibility is investigated in the case of the Hartree−Fock results by performing calculations using a series of basis sets ranging from minimal (STO-3G) to the near-Hartree−Fock limit (aug-cc-pVTZ). The sensitivity of the density functional theory calculations to the type of exchange-correlation potential energy functional is investigated by comparing results using the local density approximation with those obtained with nonlocal functionals proposed by Becke, Perdew, and Lee, Yang, and Parr. It is found that the experimental results are generally best modeled by the density functional theory calculations, with only small differences noted among the results obtained using the different potential energy functionals. In the case of the Hartree−Fock calculations, increasing the basis set size beyond that of the 6-311++G** basis set has no discernible effect on the calculated momentum profiles, which in comparison to the experimental momentum profiles tend to underestimate the intensity at low values of electron momentum, particularly for the outermost valence orbitals of glycine. This suggests that a consideration of electron correlation effects is necessary for correct modeling of the chemically sensitive outer spatial regions of the electron density of the outer valence orbitals of glycine.

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A high sensitivity momentum dispersive multichannel electron momentum spectrometer for studies in experimental quantum chemistry

Cited by 21 publications

References 18 publications

Distorted-wave effects at low momentum in binary (e, 2e) cross sections for d-orbital ionization

Distorted-wave effects at low momentum in binary (e, 2e) cross sections for d-orbital ionization

Improvements on the third generation of electron momentum spectrometer

Glycine Valence Orbital Electron Densities: Comparison of Electron Momentum Spectroscopy Experiments with Hartree−Fock and Density Functional Theories

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