Topic
Valence (chemistry)
About: Valence (chemistry) is a research topic. Over the lifetime, 24937 publications have been published within this topic receiving 645252 citations. The topic is also known as: valency.
Papers published on a yearly basis
Papers
More filters
TL;DR: Using the well established binding energies of one and two valence neutrons in the two-center α+α system (forming the states in 9Be and 10Be*) the structure of these nuclear dimers and their rotational bands including those with more than 2 nucleons are discussed using published transfer reaction data for Be and Boron isotopes as mentioned in this paper.
Abstract: Using the well established binding energies of one and two valence neutrons in the two-center α+α system (forming the states in 9Be and 10Be*) the structure of these nuclear dimers and their rotational bands including those with more than 2 nucleons are discussed using published transfer reaction data for Be and Boron isotopes. Based on the 0
2
+
state in 12C which is supposed to be an 3α particle chain at an excitation energy of 7.65 MeV and using the binding energy of these valence neutrons in 9Be and 10Be*, chain states in the system 12C* + x neutrons are constructed. The energy position of the lowest chain states are estimated and ways for their population in reactions on 9Be and using radioactive beams are proposed. It is expected that these states are metastable and could have appreciable branches for γ-decay. Further extrapolations to longer chain states (polymers) in neutron rich light isotopes are made.
137 citations
TL;DR: In this paper, the semi-empirical tight-binding method was used to construct accurate valence bands for bulk Si and Ge using Hamiltonian parameters through second neighbors, and the density of surface bands and resonances associated with atomic layers near the surface was calculated.
Abstract: The semiempirical tight-binding method is used to construct accurate valence bands for bulk Si and Ge using Hamiltonian parameters through second neighbors. One additional parameter is used to describe surface relaxation (back-bond contraction). The density of surface bands and resonances associated with atomic layers near the surface is calculated. Surprisingly, the resonances are found to contribute to the surface density of states almost as effectively as proper surface states. Comparison with ion-neutralization, electron-energy loss, and ultraviolet photoemission data is made.
137 citations
TL;DR: The electronic structure of rare-earth nitrides has been studied systematically using the ab initio self-interaction corrected local-spin density approximation as discussed by the authors, which allows both a localized description of the rare earth f electrons and an itinerant description of valence electrons.
Abstract: The electronic structure of the rare-earth nitrides is studied systematically using the ab initio self-interaction corrected local-spin-density approximation. This approach allows both a localized description of the rare-earth f electrons and an itinerant description of the valence electrons. Localizing different numbers of f electrons on the rare-earth atom corresponds to different valencies, and the total energies can be compared, providing a first-principles description of valence. We show that these materials have a broad range of electronic properties including forming a different class of half-metallic magnets with high magnetic moments, and are strong candidates for applications in spin-filtering devices.
137 citations
TL;DR: In this paper, the positions of the sigma* antibonding valence MOs in benzene and its fluorinated derivatives were analyzed in an effort to trace the positions in the inner-shell electron energy loss and magnetic circular dichroism spectra.
Abstract: Electron transmission, inner-shell electron energy loss and magnetic circular dichroism spectra have been analyzed in an effort to trace the positions of the sigma* antibonding valence MOs in benzene and its fluorinated derivatives. The correlation of negative-ion resonances in these systems shows clearly that a sigma* valence level descends with increasing fluorination so as to become the lowest virtual MO in hexafluorobenzene. In addition to the low-lying sigma* negative-ion shape resonances, several negative-ion Feshbach resonances are identified as involving 3s and 3p Rydberg orbitals. The carbon K-shell spectra of benzene and its fluorinated derivatives below the respective C 1s ionization potentials are dominated by excitations to 1..pi..* and 2..pi..* valence levels. A systematic shift of the sigma* levels to lower energy with increasing fluorination is observed which is consistent with the perfluoro effect. Resonances terminating at sigma*(C-C) are found to dominate the C 1s near continuum, with dramatic enhancement of these transitions in the more highly fluorinated species. Investigation of hexafluoro- and 1,2,4,5-tetrafluorobenzene by vacuum-ultraviolet magnetic circular dichroism in the vapor phase confirms the presence of bands which are not ..pi.. ..-->.. ..pi..*. Once again, low-lying sigma* MOs are invoked as terminating orbitals.
136 citations
TL;DR: This analysis provides the first precise crystal and molecular structural parameters for α-D-glucose, including the C—C, C—H, and O—H bond lengths, and the valence angle of the ring oxygen is 113.8 degrees.
Abstract: This analysis provides the first precise crystal and molecular structural parameters for alpha-D-glucose The C-C, C-H, and O-H bond lengths deviate only slightly from their means of 1523 A, 1098 A, and 0968 A The C(1)-O(1) bond length, 1389 A, is significantly shorter than the mean value, 1420 A, of the other C-O bonds The valence angle of the ring oxygen is 1138 degrees
136 citations