Ab initio calculations of X-ray emission from C60

Guo, Jinghua; Luo, Yi; Vahtras, Olav; Skytt, P.; Wassdahl, N.; Ågren, Hans; Nordgren, Joseph

doi:10.1016/0009-2614(94)00798-5

Cited by 14 publications

(6 citation statements)

References 35 publications

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“…According to ab initio Hartree-Fock frozen-orbital model calculations, the first emission band E 1 corresponds to the highestoccupied molecular orbital of C 60 with the 4h u symmetry, while the second band E 2 represents a combination of the nearly degenerate 4g g and 7h g orbitals of C 60 . 17 Bands E 3 and E 4 contain more complicated molecular-orbital combinations, in which are included three h g , three g u , one h u , one g g , one a g , and one t 1u states. Band E 5 contains the 2h u , 3t 1u and 2g g orbitals of C 60 .…”

Section: Resultsmentioning

confidence: 99%

“…For the spectrum of pure C 60 , the first absorption band (A 1 ) with a peak at 284.5 eV has been assigned to the lowest-unoccupied molecular orbital ͑LUMO͒ of C 60 , which has the t 1u symmetry. 17,18 This peak is due to the * resonance of C 60 . The second band (A 2 ) at 286.5 eV exhibits a double-peak structure and has been assigned to the second-lowest-unoccupied orbital, with the t 1g symmetry, and the third-and fourth-unoccupied orbitals, with t 2u and h g symmetries.…”

Section: Methodsmentioning

confidence: 97%

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Formation of titanium fulleride studied by x-ray spectroscopies

Norin

Guo

et al. 1999

Phys. Rev. B

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The chemical interaction between titanium and C 60 in coevaporated titanium-fulleride films has been investigated by x-ray photoelectron spectroscopy, ͑XPS͒, x-ray absorption spectroscopy ͑XAS͒, and x-ray emission spectroscopy. Two titanium-fulleride films with different Ti concentrations ͑xϭ2.1 and 3.6͒ and a pure C 60 film were chosen in this study. C 1s XPS analyses show a binding-energy shift and a line-broadening effect. C 1s XAS study of Ti 2.1 C 60 shows a small change of the * absorption resonance, with respect to its intensity and energy position, and a variation of the spectral shape in the * absorption region in comparison with pure C 60 . The C K␣ x-ray emission spectra of the films show the same total emission bandwidth as pure C 60 . For resonant and nonresonant excitations, an x-ray spectral profile similar to pure C 60 is observed from the Ti 2.1 C 60 film, while the Ti 3.6 C 60 film results in a spectral profile with some contribution from titanium carbide. All the experimental results indicate that a titanium-fulleride compound has been formed in the coevaporation process of C 60 and titanium. ͓S0163-1829͑99͒03119-7͔

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 97%

Formation of titanium fulleride studied by x-ray spectroscopies

Norin

Guo

et al. 1999

Phys. Rev. B

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“…It has been observed that the Koopmans energy is a reasonably good approximation for the ionization potential ͑IP͒ of the outermost valence orbitals, but that it can significantly overestimate the inner-valence orbital values, so that the total width of the valence UPS spectrum can be exaggerated. [13][14][15] A widely accepted way of dealing with this departure in polymer systems, 13,15 is based on a rescaling of the valence-band energy dividing by a factor of 1.3. Comparing with the experimental values, this rescaling works well for ethylene, butadiene, and hexatriene.…”

Section: Energy Rescalingmentioning

confidence: 99%

Partial channel photoionization cross sections of polyenes

Carravetta¹,

Yang

Ågren

1997

Phys. Rev. B

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We present calculations of partial channel photoionization cross sections and photoelectron spectra of polyenes in the ultraviolet wavelength region. The dependences on molecular size, up to C 16 H 18 , on photon energy, including He I and He II spectra, and on the particular ionization channel have been investigated using the independent-channel static exchange method. The channel dependence of the He I cross sections, which is quite strong for ethylene, diminishes, as the molecular length is increased, and becomes weak in the He II region. The energy dependence, which is strong in the He I region for all molecules and/or channels, is also insignificant for He II excitation, with the cross sections of all channels being close to each other. The cross sections are remarkably constant for the different levels at any given photon energy. Spectral analyses for the first three smallest molecules-ethylene, butadiene, and hexatriene-show that the independent-channel approach is able to reproduce experimental data quite well.

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“…The analysis of the RIXS process requires in general a one-step formalism, which leads to a Kramers-Heisenberg-type dispersion formula for the cross section. The general theory for a RIXS spectrum of randomly oriented molecular and polymeric systems have been presented in previous works [15,9,19,20,21] and is also applied for this study. For the general description of calculations of non-resonant inelastic X-ray scattering and X-ray absorption spectra (NEXAFS), we also refer to earlier studies [15,9,10,12,13], and to Ref.…”

Section: Calculationsmentioning

confidence: 99%

The electronic structure of poly(pyridine-2,5-diyl) investigated by soft X-ray absorption and emission spectroscopies

et al. 1998

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The electronic structure of poly(pyridine-2,5-diyl) investigated by soft X-ray absorption and emission spectroscopies, 1998, Chemical Physics, (237), 3, 295-304 AbstractThe electronic structure of the poly-pyridine conjugated polymer has been investigated by resonant and nonresonant inelastic X-ray scattering and X-ray absorption spectroscopies using synchrotron radiation. The measurements were made for both the carbon and nitrogen contents of the polymer. The analysis of the spectra has been carried out in comparison with molecular orbital calculations taking the repeat-unit cell as a model molecule of the polymer chain. The simulations indicate no significant differences in the absorption and in the non-resonant X-ray scattering spectra for the different isomeric geometries, while some isomeric dependence of the resonant spectra is predicted. The resonant emission spectra show depletion of the π electron bands in line with symmetry selection and momentum conservation rules. The effect is most vizual for the carbon spectra; the nitrogen spectra are dominated by lone pair n orbital emission of σ symmetry and are less frequency dependent.

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Ab initio calculations of X-ray emission from C60

Cited by 14 publications

References 35 publications

Formation of titanium fulleride studied by x-ray spectroscopies

Formation of titanium fulleride studied by x-ray spectroscopies

Partial channel photoionization cross sections of polyenes

The electronic structure of poly(pyridine-2,5-diyl) investigated by soft X-ray absorption and emission spectroscopies

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