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Photoexcitation processes in atoms
Alojz Kodre, Iztok Arčon, Jana Padežnik Gomilšek, 2021, samostojni znanstveni sestavek ali poglavje v monografski publikaciji

Opis: Photoelectric absorption is characterized by a smooth power-law decrease of the cross section with photon energy. Absorption edges reveal rich structure, which continues into the high-energy side. The quasiperiodic signal, superposed onto the smooth basis, due to scattering of the photoelectron on the neighbours of the target atom provides the basis for the structural (XAFS) analysis of the material. Irregular tiny resonances and edges that appear over the same general range as XAFS are recognized as intra-atomic effects: multielectron excitations (MEE) owing to correlated motion in the electronic cloud. The systematic study of MEE began on noble gases and metallic vapours, both of which are gases of free atoms. With some extremely strong MEE, mostly coexcitations of the subvalence d and f electrons, the structural XAFS analysis may be compromised; hence, there is a need to independently determine the MEE signal, the atomic absorption background (AAB) for the analyzed element, and remove it prior to analysis. In view of the scarcity of elements which can practically be prepared in a free-atom gas state, several approaches to approximate the AAB have been developed: analysis of disordered compounds, where the weak and simple XAFS signal can be modelled and removed, and correlation analysis of the absorption spectra of several independent samples, where the AAB is extracted in an iterative procedure.
Ključne besede: photoexcitation, XAFS, multielectron excitations, atomic absorption background
Objavljeno v RUNG: 15.12.2021; Ogledov: 1032; Prenosov: 0
Gradivo ima več datotek! Več...

Evidence of enhanced photocurrent response in corannulene films
Nadya Patukhova, Layla Martin Samos, Egona Pavlica, Gvido Bratina, 2017, izvirni znanstveni članek

Opis: Photoconductivity spectra measured in non-crystalline corannulene thin layers are compared to optical absorption in solution phase and thin films. The unexpected enhanced photoconductivity is correlated with GW–BSE theoretical predictions of corannulene gas-phase excitonic spectra. Theoretical analysis reveals a consistent contribution involving transitions to Super Atomic Molecular Orbitals (SAMOs), a unique set of diffuse orbitals typical of curved conjugated constructs. Results suggest SAMO population via direct photoexcitation as a potential mechanism towards exploiting these diffuse orbitals as conducting channels in suitably assembled quantum nanostructures or solids.
Ključne besede: Coranulene, photoconductivity, thin layers, photoexcitation
Objavljeno v RUNG: 26.09.2017; Ogledov: 3212; Prenosov: 198
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