References of "Delwiche, Jacques"
     in
Bookmark and Share    
Full Text
Peer Reviewed
See detailThe nonlinear optical, magnetic, and Mossbauer spectral properties of some iron(III) doped silica xerogels
Rebbouh, L.; Rosso, Vanessa ULg; Renotte, Yvon ULg et al

in Journal of Materials Science (2006), 41(10), 2839-2849

Iron(III) species dispersed in silica have been synthesized with a sol-gel process. The iron(III) was introduced as the acetylacetonate complex into a solution of tetraethoxysilane to yield, after ... [more ▼]

Iron(III) species dispersed in silica have been synthesized with a sol-gel process. The iron(III) was introduced as the acetylacetonate complex into a solution of tetraethoxysilane to yield, after evaporative drying, pellets or monoliths. Two gels were dried very slowly over a period of five months in order to prepare a defect free monolith useful for nonlinear optical studies. Z-scan experimental studies on the resulting, transparent, monolithic, doped solid revealed an optical Kerr effect, a third order nonlinear optical phenomenon showing a linear dependence of the refractive index on the irradiance with a nonlinear refractive index, n(2), of -1.95 x 10(-11) cm(2)/W. Magnetic susceptibility studies between 4.2 and 295 K revealed paramagnetic behavior with a Curie constant of 4.433 (emu/mol)K and a Weiss temperature of -7.1 K. Magnetization studies at 5 K and at applied fields of up to 4 T and Mossbauer spectral studies between 4.2 and 295 K revealed a 50:50 mixture of paramagnetic species and nanoparticles with an average particle radius of 1.3 +/- 0.2 nm. A blocking temperature of 70 K and a magnetic anisotropy energy of 2.4 x 10(5) J/m(3) stop are derived from the Mossbauer spectra. (c) 2006 Springer Science + Business Media, Inc. [less ▲]

Detailed reference viewed: 59 (10 ULg)
Full Text
Peer Reviewed
See detailA structural, magnetic, and Mossbauer spectral study of several Na-Mn-Fe-bearing alluaudites
Hatert, Frédéric ULg; Long, G. J.; Hautot, D. et al

in Physics and Chemistry of Minerals (2004), 31(8), 487-506

The synthesis and the chemical, structural, magnetic, and Mossbauer spectral characterization of three synthetic alluaudites, Na2Mn2Fe(PO4)(3), NaMn Fe-2(PO4)(3) and (Na2MnFeFeIII)-Fe-II(PO4)(3), and a ... [more ▼]

The synthesis and the chemical, structural, magnetic, and Mossbauer spectral characterization of three synthetic alluaudites, Na2Mn2Fe(PO4)(3), NaMn Fe-2(PO4)(3) and (Na2MnFeFeIII)-Fe-II(PO4)(3), and a natural sample with the nominal composition of NaMn Fe-2(PO4)(3), collected in the Buranga pegmatite, Rwanda, are reported. All four compounds have the expected alluaudite monoclinic C2/c structure with the general formula [A(2)A(2)'][A(1)A(1)'A(1)(2)'']M(1)M(2)(2)(PO4)(3) in which manganese(II) is on the M(1) site and manganese(II), iron(III) and, in some cases, iron(II) on the M(2) site. The X-ray structure of Na2Mn2Fe(PO4)(3) also indicates a partially disordered distribution of Na-I and Mn-II on the M(1) and A(1) crystallographic sites. All four compounds are paramagnetic above 40 K and antiferromagnetically ordered below. Above 40 K the effective magnetic moments of NaMnFe2(PO4)(3) and Na2MnFeII Fe-III(PO4)(3) are those expected of high-spin manganese(II) and iron(III) with the (6)A(1g) electronic ground state and high-spin iron(II) with the T-5(2g) electronic ground state. In contrast, the effective magnetic moment of Na2Mn2Fe(PO4)(3) is lower than expected as a result of enhanced antiferromagnetic exchange coupling by the manganese(II) on the M(2) site. The Mossbauer spectra of all four compounds have been measured from 4.2 to 295 K and have been found to be magnetically ordered below 40 K for Na2Mn2Fe(PO4)(3) and similar to35 K for the remaining compounds. The Mossbauer spectra of Na2Mn2Fe(PO4)(3) exhibit the two expected iron(III) quadrupole doublets and/or magnetic sextets expected for a random distribution of manganese(II) and iron(III) ions on the M(2) site. Further, the Mossbauer spectra of (Na2MnFeFeIII)-Fe-II(PO4)(3) exhibit the two iron(II) and two iron(III) quadrupole doublets and/or magnetic sextets expected for a random distribution of iron(II) and iron(III) on the M(2) site. Surprisingly, the synthetic and natural samples of NaMnFe2(PO4)(3) have 19 and 10% of iron(II) on the M(2) site; apparently the presence of some iron(II) stabilizes the alluaudite structure through the reduction of iron(III)-iron(III) repulsion. The temperature dependence of the iron(II) quadrupole splitting yields a 440 to 600 cm(-1) low-symmetry component to the octahedral crystal field splitting at the M(2) site. The iron(II) and iron(III) hyperfine fields observed at 4.2 K are consistent with the presence of antiferromagnetic ordering at low temperatures in all four compounds. [less ▲]

Detailed reference viewed: 56 (1 ULg)
Full Text
Peer Reviewed
See detailAnisotropic behaviour in the magnetic field dependence of the low temperature electrical resistance of calcium-doped lanthanum manganate thin films grown by RF magnetron sputtering
Vertruyen, Bénédicte ULg; Dusoulier, Laurent; Fagnard, Jean-François ULg et al

in Journal of Magnetism and Magnetic Materials (2004), 280(2-3), 264-272

We report about the magnetoresistive properties of calcium-doped lanthanum manganate thin films grown by RF magnetron sputtering on single crystalline LaAiO(3) and MgO substrates. Two orientations of the ... [more ▼]

We report about the magnetoresistive properties of calcium-doped lanthanum manganate thin films grown by RF magnetron sputtering on single crystalline LaAiO(3) and MgO substrates. Two orientations of the magnetic field with respect to the electrical current have been studied: (i) magnetic field in the plane of the film and parallel to the electrical current, and (ii) magnetic field perpendicular to the plane of the film. The film grown on LaAlO3 is characterised by an unusual magneto resistive behaviour when the magnetic field is applied perpendicular to the film plane: the appearance of two bumps in the field dependence of the resistance is shown to be related to the occurrence of anisotropic magneto resistive effects in manganate films. (C) 2004 Elsevier B.V. All rights reserved. [less ▲]

Detailed reference viewed: 59 (6 ULg)
Full Text
Peer Reviewed
See detailThe electronic states of 2-furanmethanol (furfuryl alcohol) studied by photon absorption and electron impact spectroscopies
Giuliani, A.; Walker, I. C.; Delwiche, Jacques ULg et al

in Journal of Chemical Physics (2003), 119(14), 7282-7288

The photoelectron spectrum of 2-furanmethanol (furfuryl alcohol) has been measured for ionization energies between 8 and 11.2 eV and the first three ionization bands assigned to pi(3), pi(2), and n(o ... [more ▼]

The photoelectron spectrum of 2-furanmethanol (furfuryl alcohol) has been measured for ionization energies between 8 and 11.2 eV and the first three ionization bands assigned to pi(3), pi(2), and n(o) ionizations in order of increasing binding energy. The photoabsorption spectrum has been recorded in the gas phase using both a synchrotron radiation source (5-9.91 eV, 248-125 nm) and electron energy-loss spectroscopy under electric-dipole conditions (5-10.9 eV, 248-90 nm). The (UV) absorption spectrum has also been recorded in solution (4.2-6.36 eV, 292-195 nm). The electronic excitation spectrum appears to be dominated by transitions between pi and pi* orbitals in the aromatic ring, leading to the conclusion that the frontier molecular orbitals of furan are affected only slightly on replacement of a H atom by the -CH2OH group. Additional experiments investigating electron impact at near-threshold energies have revealed two low-lying triplet states and at least one electron/molecule shape resonance. Dissociative electron attachment also shows to be widespread in furfuryl alcohol. (C) 2003 American Institute of Physics. [less ▲]

Detailed reference viewed: 23 (0 ULg)
Full Text
See detailA Magnetic and Mössbauer Spectral Study of Several Na-Mn-Fe-bearing Alluaudites
Long, Gary J.; Hautot, Dimitri; Hatert, Frédéric ULg et al

Poster (2001)

Detailed reference viewed: 4 (0 ULg)
Full Text
Peer Reviewed
See detailA magnetic and conversion electron Mossbauer spectral study of amorphous Dy20Fe80-yCoy thin films
Fleury-Frenette, Karl ULg; Delwiche, Jacques ULg; Grandjean, Fernande ULg et al

in IEEE Transactions on Magnetics (2001), 37(4), 2311-2314

Amorphous thin films of Dy20Fe80-yCoy, with 0 < y < 20 and of ca. 40 nm thickness, have been prepared by sputtering on polyimide substrates. The 295 K conversion electron Mossbauer spectra (CEMS) of these ... [more ▼]

Amorphous thin films of Dy20Fe80-yCoy, with 0 < y < 20 and of ca. 40 nm thickness, have been prepared by sputtering on polyimide substrates. The 295 K conversion electron Mossbauer spectra (CEMS) of these films consist of broadened sextets which have been analyzed with a distribution of hyperfine fields in which the iron moments are oriented perpendicular to the plane of the film, an orientation which is in agreement with the perpendicular magnetic anisotropy observed herein at 295 K by vibrating sample magnetrometry. The average hyperfine field and isomer shift increase linearly with increasing Co content. Both increases arise from an increase in the electron occupation of the 3d states as the cobalt content increases. [less ▲]

Detailed reference viewed: 21 (5 ULg)
Full Text
Peer Reviewed
See detailCharacteristics of the iron moment in Dy-Fe and Dy-FeCo amorphous alloys studied by X-ray magnetic circular dichroism
Fleury-Frenette, Karl ULg; Dhesi, S. S.; van der Laan, G. et al

in Journal of Magnetism & Magnetic Materials (2000), 220(1), 45-51

The local magnetic moment of Fe in Dy-Fe and Dy-FeCo amorphous alloys has been studied using X-ray absorption spectroscopy and X-ray magnetic circular dichroism (XMCD). The Fe orbital and spin magnetic ... [more ▼]

The local magnetic moment of Fe in Dy-Fe and Dy-FeCo amorphous alloys has been studied using X-ray absorption spectroscopy and X-ray magnetic circular dichroism (XMCD). The Fe orbital and spin magnetic moments have been obtained for a range of alloy compositions by applying the sum rules to the XMCD spectra. The room temperature variations of the average components of the Fe moments as a function of Dy concentration and with the substitution of Fe by Co have been determined. A sharp reversal of the total magnetic moment was found at 28 +/- 1 at% Dy for both alloys. (C) 2000 Elsevier Science B.V. All rights reserved. [less ▲]

Detailed reference viewed: 31 (4 ULg)
Full Text
Peer Reviewed
See detailElectronic Autoionization in Carbon monoxide: The effects of the Vibrational Motion.
Leyh, Bernard ULg; Delwiche, Jacques ULg; Hubin-Franskin, Marie-Jeanne ULg et al

in Chemical Physics (1987), 115

New continuous measurements of the vibrationally resolved photoionization cross sections of CO+ X2Sigma+ and A2Pi between 63 and 83 nm are reported. We assign the Rydberg series converging to CO+ A2Pi ... [more ▼]

New continuous measurements of the vibrationally resolved photoionization cross sections of CO+ X2Sigma+ and A2Pi between 63 and 83 nm are reported. We assign the Rydberg series converging to CO+ A2Pi. The effects of the vibrational motion are interpreted on the basis of the Condon approximation. This approximation is shown to allow a qualitative understanding of the decay of the Rydberg series converging to the A2Pi and B2Sigma+ states of CO+. [less ▲]

Detailed reference viewed: 16 (1 ULg)
Full Text
See detailMeasured and Calculated Partial Photoionization Cross Sections of CO between 15 and 40 eV.
Leyh, Bernard ULg; Raseev, G.; Hubin-Franskin, Marie-Jeanne ULg et al

in Lahmani, F.; Castex, M. C.; Collin, Jacques (Eds.) et al Photophysics and Photochemistry above 6 eV. (1985)

Vibrationally resolved partial photoionization cross sections of CO have been measured and theoretical partial cross sections have been calculated using the method of Raseev et al. and the two-step MQDT ... [more ▼]

Vibrationally resolved partial photoionization cross sections of CO have been measured and theoretical partial cross sections have been calculated using the method of Raseev et al. and the two-step MQDT formulation of Giusti-Suzor and Lefebvre-Brion. We discuss the physical nature of the shape resonances appearing in the epsilon-sigma continua and we analyze their vibrational selectivity. A new assignment of the Rydberg series converging to CO+(B2Sigma+) is suggested and their electronic and vibrational selectivity is discussed. [less ▲]

Detailed reference viewed: 39 (1 ULg)
Full Text
Peer Reviewed
See detailIntramolecular dynamics by photoelectron spectroscopy. II. Nonadiabatic processes.
Dehareng, Dominique ULg; Leyh, Bernard ULg; Desouter-Lecomte, Michèle ULg et al

in Journal of Chemical Physics (1983), 79(8), 3719-3724

The Fourier transform of an electronic spectrum leads to an autocorrelation function which provides information on the propagation of the wave packet on the potential energy surface of the electronic ... [more ▼]

The Fourier transform of an electronic spectrum leads to an autocorrelation function which provides information on the propagation of the wave packet on the potential energy surface of the electronic state reached in the transition. The formula is valid even when nonadiabatic interaction is present, i.e., when the wave packet splits at a particular surface crossing with one part branching off to another potential energy surface. An explicit expression of the correlation function is given for a model of several discrete states interacting with a continuum. Closed-form solutions are given in the case of one and two resonances. A very simple formula valid in the strong coupling limit is also derived. The method is applied to the photoelectron spectrum of state A 2Sigma+ of HBr+, which is shown to correspond to the strong couplig case. [less ▲]

Detailed reference viewed: 21 (5 ULg)
Full Text
See detailElektronenspectroscopie: een analysetechniek voor het bestuderen van oppervlakken.
Locht, Robert ULg; Delwiche, Jacques ULg

in Chemisch Weekblad (1973), 69(30/31), 21-23

The shift of electron binding energies can be measured by ESCA (Electron Spectroscopy for Chemical Analysis). This phenomenon is the basis of important data for structural analysis.

Detailed reference viewed: 38 (1 ULg)
Full Text
See detailFotoelektronen Spectroscopie: een nieuwe analyse techniek.
Locht, Robert ULg; Delwiche, Jacques ULg

in Chemisch Weekblad (1973), 69(28/29),

Beside the IR-, Raman- and UV-spectroscopies the photoelectron spectroscopy becomes an important technique for the qualitative and quantitative analysis of unknown samples. Important informations related ... [more ▼]

Beside the IR-, Raman- and UV-spectroscopies the photoelectron spectroscopy becomes an important technique for the qualitative and quantitative analysis of unknown samples. Important informations related to the electronic and molecular structure can be obtained by this technique. [less ▲]

Detailed reference viewed: 47 (5 ULg)