Semi-empirical calculation of the optical spectra of silica clusters in spark-processed silicon

Polihronov, Jeliazko G.; Hedström, Magnus; Hummel, Rolf E.; Cheng, Hai‐Ping

doi:10.1016/s0022-2313(01)00414-8

Cited by 11 publications

(5 citation statements)

References 22 publications

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“…However, luminescence seemed to be associated with at least more than two luminescence theories, such as nano-size effect and defect-related luminescence. Recent studies of theoretical calculation suggest that Si ring clusters are contributed to the optical properties of this material [26]. However, further work is necessary to identify the origin of luminescence.…”

Section: Resultsmentioning

confidence: 96%

Luminescence properties of spark-processed SiC

Chang

Sakai

2004

Materials Letters

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Section: Resultsmentioning

confidence: 96%

Luminescence properties of spark-processed SiC

Chang

Sakai

2004

Materials Letters

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“…Protonation of a U(V) ··· U(VI) complex at the HF/SDD and B3LYP/SDD levels broke the CC complex with no electron transfer between the two U centers, which would require a change in the multiplicity of the system. For the U(V) ··· U(V) complex, the spin multiplicity of the system is preserved throughout and, hence, the disproportionation reaction via this U(V) ··· U(V) CC mechanism is spin allowed and so favorable.…”

Section: Discussionmentioning

confidence: 99%

A Theoretical Study of the Inner-Sphere Disproportionation Reaction Mechanism of the Pentavalent Actinyl Ions

2007

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The inner-sphere mechanisms of the disproportionation reactions of U(V), Np(V), and Pu(V) ions have been studied using a quantum mechanical approach. The U(V) disproportionation proceeds via the formation of a dimer (a cation-cation complex) followed by two successive protonations at the axial oxygens of the donor uranyl ion. Bond lengths and spin multiplicities indicate that electron transfer occurs after the first protonation. A solvent water molecule then breaks the complex into solvated U(OH)2(2+) and UO2(2+) ions. Pu(V) behaves similarly, but Np(V) appears not to follow this path. The observations from quantum modeling are consistent with existing experimental data on actinyl(V) disproportionation reactions.

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“…This gives the best fit of the experimental lowest dipole-allowed absorption energy (6.5 eV) 14 for a spherical Si 5 H 12 cluster. Similar β values, −9.0 and −9.5 eV, were employed respectively in refs and , where the absorption spectra of molecules containing silicon atoms were calculated by the configuration interaction (CI) method. The accuracy of the INDO/S parametrization is achieved by matching it with the experimental absorption data of various small molecules.…”

Section: Methodsmentioning

confidence: 99%

Dimensionality Dependence of Optical Properties and Quantum Confinement Effects of Hydrogenated Silicon Nanostructures

Zhang

2006

J. Phys. Chem. B

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The excited state properties of linear, planar, and spherical hydrogenated silicon nanostructures are studied systematically with use of a time-dependent Hartree-Fock (TDHF) approach with a semiempirical Hamiltonian. The calculated optical gaps decrease significantly from linear, planar, to spherical silicon structures, showing that the optical gap is dimensionality dependent and hence it can be varied by solely managing the shape of the nanostructures. Remarkably, the calculated exciton sizes of the lowest dipole-allowed excited states for both silicon chains and planes are approximately 26 A, revealing that the quantum confinement effect should be significantly enhanced when the sizes of silicon nanostructures are smaller than this value but not dependent on the dimensionality. A similar trend is also observed for hydrogenated silicon spherical clusters.

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Semi-empirical calculation of the optical spectra of silica clusters in spark-processed silicon

Cited by 11 publications

References 22 publications

Luminescence properties of spark-processed SiC

Luminescence properties of spark-processed SiC

A Theoretical Study of the Inner-Sphere Disproportionation Reaction Mechanism of the Pentavalent Actinyl Ions

Dimensionality Dependence of Optical Properties and Quantum Confinement Effects of Hydrogenated Silicon Nanostructures

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