SCCC MO calculations on the ions WX2-4, MoX2-4 and VX3-4 (X = O,S,Se)

Kebabcioglu, R.; Müller, Achim

doi:10.1016/0009-2614(71)80575-4

Cited by 90 publications

(16 citation statements)

References 23 publications

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“…Figure 7 reveals that the origin of the structures 1 to 4 below 10 eV is different from that of the structures 5 to 8 above 10 eV. Molecular orbital calculations for MoO 4 2-and WO 4 2-ions by Kebabcioglu et al [21] showed that several transitions from the O 2p orbitals to the Mo 4d (W 5d) orbitals take place in the region between 5 eV and 13 eV. Zhang et al [14] studied theoretically the electronic states of CaMoO 4 and CaWO 4 , and concluded that the upper part of the valence band is mainly built up of the O 2p state of π-character and the bottom part of the conduction band is composed of the Mo 4d (W 5d) state.…”

Section: Discussionmentioning

confidence: 94%

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Comparative study of optical spectra and electronic structures of CaMoO₄ and CaWO₄ crystals

Fujita

Itoh

Takagi

et al. 2006

Physica Status Solidi (b)

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Polarized reflectivity spectra of CaMoO 4 and CaWO 4 single crystals have been measured up to 30 eV by using synchrotron radiation as a light source. The optical constants for a-and c-axes are derived from the reflectivity spectra by a Kramers -Kronig analysis. A clear correspondence is found in the main structures of the optical spectra between molybdate and tungstate. It is revealed that the lowest bands peaking at 5.0 eV in CaMoO 4 and at 6.0 eV in CaWO 4 consisit of some fine structures with distinct dichroism. They are attributed to the joint density-of-states; in other words, no structures indicative of exciton transition are found at the fundamental absorption edge. From the comparison of the spectral profiles in CaMoO 4 and CaWO 4 , the structures below 10 eV are ascribed to the transitions from the O 2p valence band to the conduction band mainly made of Mo 4d (W 5d) states, while those above 10 eV are assigned to the transitions to the Ca conduction band. The polarization dependence of the structures below 10 eV is explained well in terms of the intramolecular transition in an oxyanion complex in the scheelite crystal. The energy band structure of CaWO 4 is discussed taking into account of the previous results such as the thermostimulated luminescence and the two-photon excitation.

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Section: Discussionmentioning

confidence: 94%

“…3 and 6. molecule of T d symmetry, the highest occupied orbital is of t 1 symmetry, and the lowest and the next higher unoccupied orbitals are of e and t 2 symmetry, respectively [21]. In the scheelite crystal, the molecule is slightly compressed along the c-axis, and the symmetry is lowered to D 2d .…”

Section: Discussionmentioning

confidence: 99%

Comparative study of optical spectra and electronic structures of CaMoO₄ and CaWO₄ crystals

Fujita

Itoh

Takagi

et al. 2006

Physica Status Solidi (b)

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“…I n T, symmet,ry, the highest occupied complex state [9] is formed by oxygen 2pn orbitals and separat.ed from the first excited 2e state, which possesses transit.ion metal d-and oxygen 2p-character [ 161, by an energy of about, 5 to 6 eV even in t.he case of solid state.…”

Section: Discussionmentioning

confidence: 99%

Paramagnetic Resonance and Thermoluminescence of the PbWO₄/PbMoO₄ Mixed Crystal System

Hofstaetter

Oeder

Scharmann

et al. 1978

Physica Status Solidi (b)

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I n honour of Prof. F. ST~~CKMAKN'S 60th birthday After X-ray excitation of PbWO,/PbMoO, mixed single crystals at liquid nitrogen temperature two types of MoOB--electron centres are observed by means of EPH. For low molybdenum concentration axial S,-symmetry centres are present, whereas in the case of crystals with high molybdenum content the centres undergo a small non-axial symmetry distortion. The thermal decay of the MoOi--centres, which contributes to the thermoluminescence emission of the crystals, is discussed with respect to its concentration dependence. Nach Rontgenanregung von PbWO.,/PbMoO,-Mischkristallen bei der Temperatur des fliissigen Stickstoffes werden mit Hilfe der ESR zwei Arten von Moo;--Elektronenzentren nachgewiesen. Bei niedrigcr Molybdankonzentration liegen axiale Zentren mit S,-Symmetrie $or, wahrend im Fall hoher Molybdandotierung die Zentren einer nicht-axialen Symmetriesthmg nnterliegen. Der thermische Zerfall der MoOi--Zentren, der zur Thermolurnineszenz der Kristalle beitragt, wird beziiglich seiner Konzentrationsabhangigkeit diskutiert.

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“…In a free MoO 4 2− molecule of T d symmetry, the highest occupied orbital made of the O 2p state is of t 1 symmetry, while the lowest and next higher unoccupied orbitals made of the Mo 4d state are of e and t 2 symmetries, respectively. 27 In the scheelite crystal, the molecule is slightly compressed along the c axis and the symmetry is lowered to D 2d . Because of the surrounding ions, the site symmetry of the oxyanion molecule is further lowered to S 4 .…”

Section: Discussionmentioning

confidence: 99%

Optical anisotropy and electronic structures ofCdMoO4andCdW
Fujita
¹
,
Itoh
²
,
Katagiri
³

et al. 2008
Phys. Rev. B

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The polarized reflectivity spectra of CdMoO 4 single crystals with a scheelite structure and of CdWO 4 with a wolframite structure are measured in the 3 -30 eV range by using synchrotron radiation. The spectra of optical constants for the crystallographic axes are derived by a Kramers-Kronig analysis. X-ray photoelectron spectroscopy ͑XPS͒ and the calculation of the electronic structure by using a discrete variational X␣ method are performed for CdMoO 4 . The calculation shows that the Cd 4d state is localized at the bottom region of the O 2p valence band, and the Cd 5s state has a significant contribution to the bottom of the conduction band, composed of the Mo 4d state. The XPS spectrum of CdMoO 4 resembles that of CdWO 4 . Unlike the XPS spectrum, the optical spectra of CdMoO 4 resemble those of scheelite CaMoO 4 rather than CdWO 4 . An excitonic transition is observed as a weak shoulderlike structure in CdWO 4 , while it is not appreciable in CdMoO 4 . These experimental results are discussed in comparison with the theoretical calculation of electronic structures. The remarkable anisotropy of the optical spectra in CdMoO 4 is explained by taking into account the presence of the Cd 5s state at the bottom of the conduction band. The dichroism of CdWO 4 is discussed in terms of the chain structure of WO 6 6− octahedra in wolframite crystals. The present study indicates that the Cd metal states play a crucial role in the optical properties near the fundamental absorption edge in both CdMoO 4 and CdWO 4 .

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SCCC MO calculations on the ions WX2-4, MoX2-4 and VX3-4 (X = O,S,Se)

Cited by 90 publications

References 23 publications

Comparative study of optical spectra and electronic structures of CaMoO₄ and CaWO₄ crystals

Comparative study of optical spectra and electronic structures of CaMoO₄ and CaWO₄ crystals

Paramagnetic Resonance and Thermoluminescence of the PbWO₄/PbMoO₄ Mixed Crystal System

Optical anisotropy and electronic structures ofCdMoO4andCdW
Fujita
¹
,
Itoh
²
,
Katagiri
³

et al. 2008
Phys. Rev. B

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SCCC MO calculations on the ions WX2-4, MoX2-4 and VX3-4 (X = O,S,Se)

Cited by 90 publications

References 23 publications

Comparative study of optical spectra and electronic structures of CaMoO4 and CaWO4 crystals

Comparative study of optical spectra and electronic structures of CaMoO4 and CaWO4 crystals

Paramagnetic Resonance and Thermoluminescence of the PbWO4/PbMoO4 Mixed Crystal System

Optical anisotropy and electronic structures ofCdMoO4andCdWFujita1, Itoh2, Katagiri3 et al. 2008Phys. Rev. B

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Comparative study of optical spectra and electronic structures of CaMoO₄ and CaWO₄ crystals

Comparative study of optical spectra and electronic structures of CaMoO₄ and CaWO₄ crystals

Paramagnetic Resonance and Thermoluminescence of the PbWO₄/PbMoO₄ Mixed Crystal System

Optical anisotropy and electronic structures ofCdMoO4andCdW
Fujita
¹
,
Itoh
²
,
Katagiri
³

et al. 2008
Phys. Rev. B