J. Ghijsen | Université de Namur (University of Namur) (original) (raw)

Papers by J. Ghijsen

Research paper thumbnail of Cage relaxation effects on the local density of states in a C60 derivative

Chemical Physics Letters, 1996

A (6-6) bonded fulleroid C60(NH(CHCOOCH3)2) has been deposited on a GeS(001) crystal by molecular... more A (6-6) bonded fulleroid C60(NH(CHCOOCH3)2) has been deposited on a GeS(001) crystal by molecular beam expitaxy (MBE). XPS and LEED experiments suggest that the molecules are close packed in a (111) plane with the tail pointing to the vacuum. The local density of states of the film has been investigated by direct and inverse photoemission spectroscopies. Cage relaxation effects induced

Research paper thumbnail of ESRS 1993 Congress

Synchrotron Radiation News, 1994

Research paper thumbnail of High resolution electron energy loss spectroscopic study of the interaction of oxygen with magnesium single crystal surfaces

Journal of Electron Spectroscopy and Related Phenomena, 1983

Research paper thumbnail of Localization and hybridization of 5f states in the metallic and ionic bond as investigated by photoelectron spectroscopy

Structure and Bonding, 1985

ABSTRACT Localization versus itineracy and the degree of hybridization of 5 f states with orbital... more ABSTRACT Localization versus itineracy and the degree of hybridization of 5 f states with orbitals of the actinide atom (especially 6 d) as well as with those of the ligand in compounds are central questions for the understanding of bonding in actinide solids. Photoelectron spectroscopy provides answers to these questions. In narrow band solids, like the actinides, the interpretation of results requires the use of band calculations in the itinerant picture, as well as models of final state emission in the atomic picture. From the experimental viewpoint: l. the analysis of the variation of photoionization cross sections (affecting the intensities of photoelectron spectroscopy), gives an insight into the orbital composition of the bands of the solid; 2. the combination of direct and inverse photoemission provides a powerful tool to assess the structure of occupied and of empty states, and, in the case of localized 5 f states, permits the determination of a fundamental quantity, the Coulomb correlation energy, governing the physical properties of narrow bands. After a survey of the basic theory and some experimental aspects of photoelectron spectroscopy which are relevant to actinide solids, two systems are illustrated: elemental actinide metals, in which the Mott transition between plutonium and americium is evidenced in a “photographic” way by photoemission, and strongly ionic oxides, in which the 5 f localized behaviour is clearly seen, and indications of f-p or d-p covalent mixing are investigated.

Research paper thumbnail of Electron spectroscopy characterization of CuO and Cu2O thin films on MgO (100)

Advances in Superconductivity VIII, 1996

Research paper thumbnail of Photoemission study of the copper/poly(ethylene terephthalate) interface

Physical review. B, Condensed matter, Jan 15, 1991

ABSTRACT The metallization of poly(ethylene terephthalate) (PET) by copper has been studied by ph... more ABSTRACT The metallization of poly(ethylene terephthalate) (PET) by copper has been studied by photoelectron spectroscopy (x-ray and vacuum ultraviolet). The results are interpreted in the light of a valence-effective-Hamiltonian band-structure calculation on the PET polymeric chain and by comparison with earlier work on copper oxides. The theoretical valence-band density of states is in very good agreement with the photoelectron spectra of PET and allows us to present a detailed interpretation of the valence electronic structure of PET. Upon metallization, we find that, for low coverages (

Research paper thumbnail of Gold Clusters on Carbon Nanotubes

Transition metal atoms clustering on CNTs surfaces received increased interest during the last ye... more Transition metal atoms clustering on CNTs surfaces received increased interest during the last years owing to the possibility to use the combination of these two nanostructures as a versatile building block for the construction of modern nanodevices . By grafting suitable nanostructures to the inert sidewall of the CNTs, their electronic, electrical and chemical properties can be tailored, therefore opening a vast field of applications. For all the reported applications , knowledge of the electronic structure and control of the morphology are important issues as they dictate the conductivity, catalytic activity and reactivity. Transmission electron microscopy studies revealed that the morphology of the metal on the CNTs surface can range from a quasi-continuous metal film covering the CNTs surface to a decoration of the CNTs by isolated discrete particles, depending on the interactions between the deposited metal atoms and the CNTs substrate .

Research paper thumbnail of VUV photoemission study of Ni/GeS thin films

Research paper thumbnail of Electronic Structure Symmetry at Au-Diindenoperylene-Au Interfaces

Research paper thumbnail of A Study of the Adsorption of Molecules on Simple Metal by Photoelectron Spectroscopy: the Satellite Spectra of the Adsorbate Core Levels

Research paper thumbnail of Signature of the Surface Molecular Structure in the Valence Spectra of Octadecanethiol, 1-Cyclohexyl-12-dodecanethiol and 1, 9-Nonanedithiol Self-Assembled on Gold

Research paper thumbnail of Resonant photoemission study of Gd 4f concentration to the valence bond of IV-VI crystals

Research paper thumbnail of A New Alternative for the Low-Workfunction Electrode in Organic Devices

Research paper thumbnail of SURFACE-PLASMON SPECTROSCOPY - PHOTOELECTRON-SPECTRA FROM ADSORBATES ON ALUMINUM

Surface Science, 1979

ABSTRACT

Research paper thumbnail of LOW-ENERGY ELECTRON INELASTIC-SCATTERING AT SURFACES - APPLICATION TO MG(0001) AND (11BAR00) .1. THE CLEAN METAL-SURFACES

Surface Science, 1983

ABSTRACT

Research paper thumbnail of MANGANESE-DERIVED PARTIAL DENSITY OF STATES IN CD1-XMNXTE

Research paper thumbnail of PHOTOEMISSION-STUDY OF THE AL-SB(111) INTERFACE

Research paper thumbnail of X-RAY ABSORPTION STUDY OF THE O-2P HOLE CONCENTRATION-DEPENDENCE ON O-STOICHIOMETRY IN YBA2CU3OX

Physical Review B, 1988

... B 64, 189 (1986). 2Zhi-xun Shen, JW Allen, JJ Yeh, J.-S. Kang, W. Ellis, W. Spicer, I. Lindau... more ... B 64, 189 (1986). 2Zhi-xun Shen, JW Allen, JJ Yeh, J.-S. Kang, W. Ellis, W. Spicer, I. Lindau, MB Maple, YD Dalichaouch, MS Torikachvili, JZ Shun, and TH Geballe, Phys. Rev. ... B 69, 449 (1988). 5D. van der Marel, J. van Elp, GA Sawatzky, and D. Heit-mann, Phys. Rev. ...

Research paper thumbnail of OXYGEN 1S X-RAY-ABSORPTION EDGES OF TRANSITION-METAL OXIDES

Research paper thumbnail of RESONANT PHOTOEMISSION IN SINGLE-CRYSTAL BLACK PHOSPHORUS

Physical Review B, 1989

Resonant photoemission in single-crystal black phosphorus has been reinvestigated in detail by hi... more Resonant photoemission in single-crystal black phosphorus has been reinvestigated in detail by high-resolution spectroscopy. Partial-yield, valence-band, and constant-initial-state spectra were measured in the 2p core-exciton excitation region. We have confirmed two types of resonances at the 2p core threshold: one is a strong core-exciton-induced resonance with two final valence holes and the other is a weak Fano-type resonance. The Fano-type resonance is preferentially associated with the lower-energy spin-orbit doublet (A-A') of the core excitons (A-A' and B-B' being separated by 0.2 eV). This result elucidates the difference of the degree of localization of the core excitons, A-A' and B-B', and rules out the possibility that the L2,3VV Auger tail is solely responsible for the resonance profile.

Research paper thumbnail of Cage relaxation effects on the local density of states in a C60 derivative

Chemical Physics Letters, 1996

A (6-6) bonded fulleroid C60(NH(CHCOOCH3)2) has been deposited on a GeS(001) crystal by molecular... more A (6-6) bonded fulleroid C60(NH(CHCOOCH3)2) has been deposited on a GeS(001) crystal by molecular beam expitaxy (MBE). XPS and LEED experiments suggest that the molecules are close packed in a (111) plane with the tail pointing to the vacuum. The local density of states of the film has been investigated by direct and inverse photoemission spectroscopies. Cage relaxation effects induced

Research paper thumbnail of ESRS 1993 Congress

Synchrotron Radiation News, 1994

Research paper thumbnail of High resolution electron energy loss spectroscopic study of the interaction of oxygen with magnesium single crystal surfaces

Journal of Electron Spectroscopy and Related Phenomena, 1983

Research paper thumbnail of Localization and hybridization of 5f states in the metallic and ionic bond as investigated by photoelectron spectroscopy

Structure and Bonding, 1985

ABSTRACT Localization versus itineracy and the degree of hybridization of 5 f states with orbital... more ABSTRACT Localization versus itineracy and the degree of hybridization of 5 f states with orbitals of the actinide atom (especially 6 d) as well as with those of the ligand in compounds are central questions for the understanding of bonding in actinide solids. Photoelectron spectroscopy provides answers to these questions. In narrow band solids, like the actinides, the interpretation of results requires the use of band calculations in the itinerant picture, as well as models of final state emission in the atomic picture. From the experimental viewpoint: l. the analysis of the variation of photoionization cross sections (affecting the intensities of photoelectron spectroscopy), gives an insight into the orbital composition of the bands of the solid; 2. the combination of direct and inverse photoemission provides a powerful tool to assess the structure of occupied and of empty states, and, in the case of localized 5 f states, permits the determination of a fundamental quantity, the Coulomb correlation energy, governing the physical properties of narrow bands. After a survey of the basic theory and some experimental aspects of photoelectron spectroscopy which are relevant to actinide solids, two systems are illustrated: elemental actinide metals, in which the Mott transition between plutonium and americium is evidenced in a “photographic” way by photoemission, and strongly ionic oxides, in which the 5 f localized behaviour is clearly seen, and indications of f-p or d-p covalent mixing are investigated.

Research paper thumbnail of Electron spectroscopy characterization of CuO and Cu2O thin films on MgO (100)

Advances in Superconductivity VIII, 1996

Research paper thumbnail of Photoemission study of the copper/poly(ethylene terephthalate) interface

Physical review. B, Condensed matter, Jan 15, 1991

ABSTRACT The metallization of poly(ethylene terephthalate) (PET) by copper has been studied by ph... more ABSTRACT The metallization of poly(ethylene terephthalate) (PET) by copper has been studied by photoelectron spectroscopy (x-ray and vacuum ultraviolet). The results are interpreted in the light of a valence-effective-Hamiltonian band-structure calculation on the PET polymeric chain and by comparison with earlier work on copper oxides. The theoretical valence-band density of states is in very good agreement with the photoelectron spectra of PET and allows us to present a detailed interpretation of the valence electronic structure of PET. Upon metallization, we find that, for low coverages (

Research paper thumbnail of Gold Clusters on Carbon Nanotubes

Transition metal atoms clustering on CNTs surfaces received increased interest during the last ye... more Transition metal atoms clustering on CNTs surfaces received increased interest during the last years owing to the possibility to use the combination of these two nanostructures as a versatile building block for the construction of modern nanodevices . By grafting suitable nanostructures to the inert sidewall of the CNTs, their electronic, electrical and chemical properties can be tailored, therefore opening a vast field of applications. For all the reported applications , knowledge of the electronic structure and control of the morphology are important issues as they dictate the conductivity, catalytic activity and reactivity. Transmission electron microscopy studies revealed that the morphology of the metal on the CNTs surface can range from a quasi-continuous metal film covering the CNTs surface to a decoration of the CNTs by isolated discrete particles, depending on the interactions between the deposited metal atoms and the CNTs substrate .

Research paper thumbnail of VUV photoemission study of Ni/GeS thin films

Research paper thumbnail of Electronic Structure Symmetry at Au-Diindenoperylene-Au Interfaces

Research paper thumbnail of A Study of the Adsorption of Molecules on Simple Metal by Photoelectron Spectroscopy: the Satellite Spectra of the Adsorbate Core Levels

Research paper thumbnail of Signature of the Surface Molecular Structure in the Valence Spectra of Octadecanethiol, 1-Cyclohexyl-12-dodecanethiol and 1, 9-Nonanedithiol Self-Assembled on Gold

Research paper thumbnail of Resonant photoemission study of Gd 4f concentration to the valence bond of IV-VI crystals

Research paper thumbnail of A New Alternative for the Low-Workfunction Electrode in Organic Devices

Research paper thumbnail of SURFACE-PLASMON SPECTROSCOPY - PHOTOELECTRON-SPECTRA FROM ADSORBATES ON ALUMINUM

Surface Science, 1979

ABSTRACT

Research paper thumbnail of LOW-ENERGY ELECTRON INELASTIC-SCATTERING AT SURFACES - APPLICATION TO MG(0001) AND (11BAR00) .1. THE CLEAN METAL-SURFACES

Surface Science, 1983

ABSTRACT

Research paper thumbnail of MANGANESE-DERIVED PARTIAL DENSITY OF STATES IN CD1-XMNXTE

Research paper thumbnail of PHOTOEMISSION-STUDY OF THE AL-SB(111) INTERFACE

Research paper thumbnail of X-RAY ABSORPTION STUDY OF THE O-2P HOLE CONCENTRATION-DEPENDENCE ON O-STOICHIOMETRY IN YBA2CU3OX

Physical Review B, 1988

... B 64, 189 (1986). 2Zhi-xun Shen, JW Allen, JJ Yeh, J.-S. Kang, W. Ellis, W. Spicer, I. Lindau... more ... B 64, 189 (1986). 2Zhi-xun Shen, JW Allen, JJ Yeh, J.-S. Kang, W. Ellis, W. Spicer, I. Lindau, MB Maple, YD Dalichaouch, MS Torikachvili, JZ Shun, and TH Geballe, Phys. Rev. ... B 69, 449 (1988). 5D. van der Marel, J. van Elp, GA Sawatzky, and D. Heit-mann, Phys. Rev. ...

Research paper thumbnail of OXYGEN 1S X-RAY-ABSORPTION EDGES OF TRANSITION-METAL OXIDES

Research paper thumbnail of RESONANT PHOTOEMISSION IN SINGLE-CRYSTAL BLACK PHOSPHORUS

Physical Review B, 1989

Resonant photoemission in single-crystal black phosphorus has been reinvestigated in detail by hi... more Resonant photoemission in single-crystal black phosphorus has been reinvestigated in detail by high-resolution spectroscopy. Partial-yield, valence-band, and constant-initial-state spectra were measured in the 2p core-exciton excitation region. We have confirmed two types of resonances at the 2p core threshold: one is a strong core-exciton-induced resonance with two final valence holes and the other is a weak Fano-type resonance. The Fano-type resonance is preferentially associated with the lower-energy spin-orbit doublet (A-A') of the core excitons (A-A' and B-B' being separated by 0.2 eV). This result elucidates the difference of the degree of localization of the core excitons, A-A' and B-B', and rules out the possibility that the L2,3VV Auger tail is solely responsible for the resonance profile.