Photoionization cross-sections: a guide to electronic structure

Green, Jennifer C.; Decleva, Piero

doi:10.1016/j.ccr.2004.02.012

Cited by 59 publications

(45 citation statements)

References 69 publications

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“…This is consistent with the suggestion of Green and Decleva 37 that, in general, the l→ l + 1 transition is the dominant contribution. The profile shown in Figure 1 for the methyl radical displays the general behaviour of the cross section with photon energy for molecular orbitals with predominant 2p character.…”

Section: B Photoionization Cross Sections and Asymmetry Parameterssupporting

confidence: 93%

Excitation energies, photoionization cross sections, and asymmetry parameters of the methyl and silyl radicals

Velasco

Lavín

Dolgounitcheva

et al. 2014

The Journal of Chemical Physics

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Vertical excitation energies of the methyl and silyl radicals were inferred from ab initio electron propagator calculations on the electron affinities of CH 3 + and SiH 3 + . Photoionization cross sections and angular distribution of photoelectrons for the outermost orbitals of both CH 3 and SiH 3 radicals have been obtained with the Molecular Quantum Defect Orbital method. The individual ionization cross sections corresponding to the Rydberg channels to which the excitation of the ground state's outermost electron gives rise are reported. Despite the relevance of methyl radical in atmospheric chemistry and combustion processes, only data for the photon energy range of 10-11 eV seem to be available. Good agreement has been found with experiment for photoionization cross section of this radical. To our knowledge, predictions of the above mentioned photoionization parameters on silyl radical are made here for the first time, and we are not aware of any reported experimental measurements. An analysis of our results reveals the presence of a Cooper minimum in the photoionization of the silyl radical. The adequacy of the two theoretical procedures employed in the present work is discussed.

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Section: B Photoionization Cross Sections and Asymmetry Parameterssupporting

confidence: 93%

Excitation energies, photoionization cross sections, and asymmetry parameters of the methyl and silyl radicals

Velasco

Lavín

Dolgounitcheva

et al. 2014

The Journal of Chemical Physics

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“…7(a), after scaling by photoionization cross-section, 53 the peak positions, valence band width, and relative peak intensities of the calculated DOS (solid black line) are in good agreement with the XPS valence band. Siteand orbital-projected DOS for {U(Co 2þ ), U(Co 3þ )} ¼ {4, 0} are shown in Fig.…”

Section: Resultsmentioning

confidence: 61%

Epitaxy of polar semiconductor Co3O4 (110): Growth, structure, and characterization

Kormondy

Posadas

Slepko

et al. 2014

Journal of Applied Physics

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Articles you may be interested inMagnetic and structural properties of BiFeO3 thin films grown epitaxially on SrTiO3/Si substrates J. Appl. Phys. 113, 17D919 (2013) The (110) plane of Co 3 O 4 spinel exhibits significantly higher rates of carbon monoxide conversion due to the presence of active Co 3þ species at the surface. However, experimental studies of Co 3 O 4 (110) surfaces and interfaces have been limited by the difficulties in growing high-quality films. We report thin (10-250 Å ) Co 3 O 4 films grown by molecular beam epitaxy in the polar (110) direction on MgAl 2 O 4 substrates. Reflection high-energy electron diffraction, atomic force microscopy, x-ray diffraction, and transmission electron microscopy measurements attest to the high quality of the as-grown films. Furthermore, we investigate the electronic structure of this material by core level and valence band x-ray photoelectron spectroscopy, and first-principles density functional theory calculations. Ellipsometry reveals a direct band gap of 0.75 eV and other interband transitions at higher energies. A valence band offset of 3.2 eV is measured for the Co 3 O 4 /MgAl 2 O 4 heterostructure. Magnetic measurements show the signature of antiferromagnetic ordering at 49 K. FTIR ellipsometry finds three infrared-active phonons between 300 and 700 cm À1

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“…While the cross sections for s-and p-electrons in atoms or small molecules are typically maximal directly at the ionization threshold, 32 there exists a centrifugal barrier for d and f electrons that causes the maximum ionization cross section to be at higher energies. 33,34 These so called shape resonances can also occur in smaller molecules if the continuum wavefunction of the outgoing electron has components with a high l value, e.g., for the Σ states in CO. 35,36 The highest lying resonance in CO can be found at photon energies of 32 eV for the B 2 Σ + state.…”

Section: A Photon Energy Dependence Of the Electron Spectramentioning

confidence: 99%

Ionization and photofragmentation of Ru3(CO)12 and Os3(CO)12

Schalk

Josefsson

Richter

et al. 2015

The Journal of Chemical Physics

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In this paper, we use a combination of photoelectron spectroscopy, mass spectrometry, and density functional theory calculations to get a detailed understanding of valence single and double ionization and the subsequent dissociation processes. This is exemplified on benchmark systems, trimetallo-dodecacarbonyls M 3 (CO) 12 with M = Ru, Os, where the energy remaining in the molecule after photoionization can be retrieved by measuring the degree of fragmentation of the molecular ion. The intensity of different mass peaks can thus be directly related to ionization cross sections obtained by photoelectron spectroscopy. We find that the M-CO dissociation energy rises as the number of CO ligands decreases due to dissociation. Moreover, ionization of the CO ligands has a higher cross section than that of the metal center for both single and double ionization. After advanced fragmentation, a CO bond can break and the carbon atom remains bonded to the metal core. In addition, we found that the valence ionization cross sections of M 3 (CO) 12 are maximal at about 40 eV photon energy thus showing a more pronounced shape resonance than Ru and Os-complexes with a single metal atom center. Finally, an np → nd giant resonance absorption causes a significant increase of the ionization cross section above 50 eV for Ru 3 (CO) 12 . C 2015 AIP Publishing LLC. [http://dx

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Photoionization cross-sections: a guide to electronic structure

Cited by 59 publications

References 69 publications

Excitation energies, photoionization cross sections, and asymmetry parameters of the methyl and silyl radicals

Excitation energies, photoionization cross sections, and asymmetry parameters of the methyl and silyl radicals

Epitaxy of polar semiconductor Co3O4 (110): Growth, structure, and characterization

Ionization and photofragmentation of Ru3(CO)12 and Os3(CO)12

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