References of "Locht, Robert"
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See detailDissociative Ionization by low energy Electron Impact. Ion Energy Distribution of N++ from N2 and O++ from O2.
Locht, Robert ULg; Momigny, J.

in Electronic and Atomic Collisions: Abstracts of Contributed Papers. (1979)

The kinetic energy distribution of the doubly ionized species N++/N2 and O++/O2 , as produced by electron impact, is reported and discussed.

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See detailDissociative Ionization of CH4 and CD4 by low energy Electron impact. The Proton Formation.
Olivier, J. L.; Locht, Robert ULg; Momigny, J.

in Electronic and Atomic Collisions: Abstract of contributed papers. Volume 1. (1979)

The kinetic energy distributions of H+(D+)/CH(D)4 are produced at variable electron impact energies. Two different features are observed and are interpreted in terms of dissociative autoionization.

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See detailDissociative Ionization by low energy Electron Impact. Energy Distribution and Appearance Energy of Doubly Ionized Fragments from N2 and O2.
Locht, Robert ULg; Momigny, J.

in Chemical Physics Letters (1979), 66(3), 574-577

Ion energy distributions and threshold energies are measured for the appearance of N2+ from N2. To our knowledge the same data are measured for the first time on O2+ from O2. For both ions a thermal peak ... [more ▼]

Ion energy distributions and threshold energies are measured for the appearance of N2+ from N2. To our knowledge the same data are measured for the first time on O2+ from O2. For both ions a thermal peak is observed in the ion energy distribution having an onset at (61.1+/-0.5) eV and (60.5+/-0.8) eV for the N2+ ion and the O2+ ion respectively. The appearance energy of higher energetic ions is measured and interpreted. [less ▲]

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See detailDissociative Autoionization as a Mechanism for the Proton Formation from Methane and Methane-d4 by low energy Electron Impact.
Locht, Robert ULg; Olivier, J. L.; Momigny, J.

in Chemical Physics (1979), 43

The ion energy distribution and the electroionization efficiency curves of H+ and D+ from methane and methane-d4 have been examined. The existence of thermal ions is unambiguously evidenced and the two ... [more ▼]

The ion energy distribution and the electroionization efficiency curves of H+ and D+ from methane and methane-d4 have been examined. The existence of thermal ions is unambiguously evidenced and the two lowest appearance thresholds of H+ are measured at (21.3+/-0.3) eV and (22.17+/-0.1) eV. At both energies the protons have to be formed through dissociative autoionization. The present results closely parallel those of the dissociative excitation experiments on methane. The Jortner-Rice model for dissociation of polyatomic molecules is invoked to account for both the appearance of H+ and high-Rydberg H atoms from CH4. [less ▲]

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See detailThe Rotational Predissociation of the CH4+ and CD4+ Ions.
Flamme, J. P.; Wankenne, H.; Locht, Robert ULg et al

in Chemical Physics (1978), 27

The metastable transitions producing CH3+/CH4 and CD3+/CD4 have been investigated by means of translational spectroscopy. For the first time structures are observed in a metastable peak corresponding to ... [more ▼]

The metastable transitions producing CH3+/CH4 and CD3+/CD4 have been investigated by means of translational spectroscopy. For the first time structures are observed in a metastable peak corresponding to the dissociation of a polyatomic ion. They are interpreted by tunneling through a rotational barrier from discrete quasi-bound states. Kinetic energy releases have been measured. [less ▲]

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See detailThe Dissociative Ionization of Carbon Monoxide.
Locht, Robert ULg

in Chemical Physics (1977), 22

The dissociative ionization of CO by low energy electron impact into C+ and O (or O-) and O+ and C (or C-) is investigated using ion energy and mass analysis. The kinetic energy distributions are studied ... [more ▼]

The dissociative ionization of CO by low energy electron impact into C+ and O (or O-) and O+ and C (or C-) is investigated using ion energy and mass analysis. The kinetic energy distributions are studied as a function of the impinging electron energy. The threshold energies of C+ and O+ are measured as a function of the released kinetic energy. The formation of the products in their ground level and with a small amount of kinetic energy mainly occurs through predissociation. The CO+ electronic states involved in these processes are tentatively identified. New evidences have been found for the importance of dissociative ionization via autoionization. [less ▲]

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See detailThe Metastable Décomposition of Methane.
Flamme, J. P.; Wankenne, H.; Locht, Robert ULg et al

in International Conference on the Physics of Electronic and Atomic Collisions: abstract of papers. Volume 1. (1977)

The metastable decomposition of CH(D)4+ into CH(D)3+ and H(D) is investigated in a tandem mass spectrometer. The results are interpreted in terms of rotational predissociation of CH(D)4+. A semi-classical ... [more ▼]

The metastable decomposition of CH(D)4+ into CH(D)3+ and H(D) is investigated in a tandem mass spectrometer. The results are interpreted in terms of rotational predissociation of CH(D)4+. A semi-classical model is developed. [less ▲]

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See detailA new test of Translational Spectroscopy: the Rotational Predissociation of the X1Sigma state of HeH+.
Fournier, P. G.; Comtet, G.; Odom, R. W. et al

in Chemical Physics Letters (1976), 40(1), 170-173

We reported the experiment on the accurate measurement of the kinetic energy released during the predissociation of HeH+ ions into the fragments H+ and He. This experiment was carried out on two machines ... [more ▼]

We reported the experiment on the accurate measurement of the kinetic energy released during the predissociation of HeH+ ions into the fragments H+ and He. This experiment was carried out on two machines specially designed for this purpose. The new results differ from those of the original experiment and agree now very well with the theoretical predictions. [less ▲]

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See detailDissociative Ionization of Carbon Disulphide in the Gas Phase. Heat of Formation of the CS Radical.
Hubin-Franskin, Marie-Jeanne ULg; Locht, Robert ULg; Katihabwa, J.

in Chemical Physics Letters (1976), 37(3), 488-493

Measurements of the appearance potentials and the kinetic energies of S+ and CS+ ions formed by electron impact on carbon disulphide in the gas phase lead us to propose a value as low as 34+/-6 kcal/mole ... [more ▼]

Measurements of the appearance potentials and the kinetic energies of S+ and CS+ ions formed by electron impact on carbon disulphide in the gas phase lead us to propose a value as low as 34+/-6 kcal/mole for the heat of formation of the CS radical in its ground electronic state. It is also shown that the predissociation of the A2Piu or X2Pig and the B2Sigmau/+ molecular ion states by a repulsive 4Sigma- state giving rise to S+ ions, observed through metastastable ions study, occur at 13.45 eV and 14.55 eV respectively. [less ▲]

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See detailThe rotational Predissociation of HeH+: Energy and Lifetime measurements.
Locht, Robert ULg; Maas, J. G.; Van Asselt, N.P.F.B. et al

in Chemical Physics (1976), 15

Relative lifetimes and energies above the dissociation limit have been determined for the rotational predissociation of several quasibound levels of the X1Sigma+ state of 4HeH+. In particular the ... [more ▼]

Relative lifetimes and energies above the dissociation limit have been determined for the rotational predissociation of several quasibound levels of the X1Sigma+ state of 4HeH+. In particular the lifetimes are very sensitive to the shape of the potential energy curve. These measurements are used to discriminate between two ab initio potential curves which differ by only 0.00004 a.u. (about 1 meV). Using the lifetime data, relative population factors were determined for the observed levels. [less ▲]

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See detailThe dissociative Ionization of CO by Electron Impact: the C+ ion formation.
Locht, Robert ULg; Dürer, J. M.

in Risley, J. S.; Geballe, R. (Eds.) Electronic and Atomic Collisions. Abstracts of papers of the IXth International Conference on the Physics of Electronic and Atomic Collisions. (1975)

The dissociative ionization of CO by low-energy electron impact is presented. The results on the dissociation channel of C+ formation has been investigated and is discussed.

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See detailThe Dissociative Ionization of Nitrogen.
Locht, Robert ULg; Schopman, Joop; Wankenne, H. et al

in Chemical Physics (1975), 7

Energy distributions and appearance potentials of N+ ions produced by low-energy electron impact on N2 have been measured. At least five dissociaton limits were detected either directly or by ... [more ▼]

Energy distributions and appearance potentials of N+ ions produced by low-energy electron impact on N2 have been measured. At least five dissociaton limits were detected either directly or by extrapolation of the 1/2 slope straight lines drawn through the kinetic energy versus appearance potential energy diagram. Fine structure observed at low energy has been interpreted by the predissociation of at least two N2+ excited states one of which being the well-known C2Sigmau/+ state. One of the others could be a 2Piu state predissociated to the dissociation limit at 24.34 eV. Close correlation between the results of the present work and the photoelectron spectroscopic observations could be done over the electron energy range between 24.3 eV and 36 eV and assignments are discussed in detail. [less ▲]

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See detailThe Dissociative Ionization in Oxygen.
Locht, Robert ULg; Schopman, Joop

in International Journal of Mass Spectrometry and Ion Physics (1974), 15

Dissociative ionization in O2 has been examined by means of a retarding potential lens combined with a quadrupole mass spectrometer. This particular arrangement made possible detailled analysis of the O ... [more ▼]

Dissociative ionization in O2 has been examined by means of a retarding potential lens combined with a quadrupole mass spectrometer. This particular arrangement made possible detailled analysis of the O+ ions kinetic energy distribution and the measurement of threshold energies of O+ ions with known kinetic energy. These two types of informations bring new experimental evidence, besides direct dissociative ionization of O2, for predissociation of the B2Sigma-/g state, the 2Piu state and the c4Sigma-/u state of O2+. A new predissociation of the O2+(2Deltag) state has been found. At low ion energy the predissociation of the 2Phiu state or an autoionizing predissociation is observed. [less ▲]

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See detailThe observation of Predissociations in the Oxygen Molecular Ion by low-energy electron impact.
Locht, Robert ULg; Schopman, Joop

in Chemical Physics Letters (1974), 26(4), 596-600

The kinetic energy distribution of the O+ ions formed by dissociative ionization of O2 has been carefully examined in the range of 0.0 to 1.3 eV. In the peak at 600 meV fine structure is observed and ... [more ▼]

The kinetic energy distribution of the O+ ions formed by dissociative ionization of O2 has been carefully examined in the range of 0.0 to 1.3 eV. In the peak at 600 meV fine structure is observed and interpreted by predissociation. The high energy side of the peak has been ascribed to the predissociation of the 2Deltag, B2Sigma-/g and the C4Sigma-/u states of O2+. The low energy side of the peak is presumably due to the predissociation of the b4Sigma-/g or the 2Phiu state of O2+ or to autoionizing predissociation. [less ▲]

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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.

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See detailDissociative Ionization of O2 by Electron Impact.
Locht, Robert ULg; Schopman, Joop

in Cobic, B. C.; Kurepa, M. V. (Eds.) Electronic and Atomic Collisions. Abstract of Papers. VIII ICPEAC, Beograd, 1973. Volume 1. (1973)

The dissociative ionization by electron impact of O2 is presented: the kinetic energy distribution of O+ and the major structures characterized by their energy.

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See detailDissociative Ionization of N2 by Electron Impact.
Locht, Robert ULg; Schopman, Joop

in Cobic, B. C.; Kurepa, M. V. (Eds.) Electronic and Atomic Collisions. Abstracts of Papers: VIII ICPEAC, Beograd, 1973. Volume 1. (1973)

The dissociative ionization by electron impact of N2 is presented: the kinetic energy distribution of N+ and the major features characterized by their energy.

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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 ▲]

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See detailAbout the use of the empirical relations hnu(CT/Max)=f(ID) for the interpretation of ionization potentials.
Locht, Robert ULg; Cahay, René ULg; Momigny, Jacques et al

in Bulletin de l'Académie Royale des Sciences, des Lettres et des Beaux-Arts de Belgique. Sciences (1972), LVIII(7), 821-840

The UV absorption spectra of the charge transfer (CT) complexes formed by iodine with C2H2NH, C2H2O and C2H2S were studied in order to interprete the first ionization potential of these organic molecules ... [more ▼]

The UV absorption spectra of the charge transfer (CT) complexes formed by iodine with C2H2NH, C2H2O and C2H2S were studied in order to interprete the first ionization potential of these organic molecules by using the empirical relationships hn(CT/Max)=f(ID). Taking into account the basical specificity of these relations, the trend of the CT data shows C2H2NH and C2H2O to be n-donors towards iodine and the first ionization potential of the same donors could be ascribed to the removal of an electron from a non-bonding orbital localized on the heteroatom. Theoretical calculations however do not support this interpretation in the case of C2H2NH. [less ▲]

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See detailEtude par Spectrométrie de Masse de la formation d'Ions Négatifs par Attachement Electronique Dissociatif et par le processus de Paire d'Ions.
Locht, Robert ULg

Doctoral thesis (1971)

The aim of this work is to investigate the appearance of negative ions by both the mechanism of Dissociative Electron Attachment (DEA) and Ion Pair processes (IPP) by electron impact. Using the ... [more ▼]

The aim of this work is to investigate the appearance of negative ions by both the mechanism of Dissociative Electron Attachment (DEA) and Ion Pair processes (IPP) by electron impact. Using the appropriate instrumentation (a conventional Nier type mass spectrometer) the best conditions are chosen to ensure ion-molecule collision free ion production (sample pressure, impinging electron beam current), the linearity of the electron energy scale between 2 eV and 100 eV and to minimize mass (and translational kinetic energy) discrimination. The used ionizing electron beam allowed us a resolution of 0.5 eV. An ionization model for both processes is proposed to provide us a method for the measurement of the threshold energy of DEA and IPP. Were necessary the numerical derivation of the ion current (for IPP) and the deconvolution of the ionization efficiency curves (for both DEA and IPP) are applied to increase the accuracy of the threshold energy determination and the resolution of the successive ion producing processes to be observed. DEA and IPP’s are observed and threshold energies are measured and assigned in: (i) diatomic molecules, i.e. H2, CO, NO and O2, (ii) triatomic molecules, i.e. CO2 and CS2 along the reaction paths providing O- and S- and CS-. No CO- ion has been detected. (iii) polyatomic molecules, i.e. CH4, C2H2, C2H4, C2H3F and C2H3Cl. Beside the monoatomic negative ions (H-, C-), diatomic and polyatomic negative ions are detected. For several of these species the electron affinity (EA) of the radical is not known, e.g. CH, C2 and C2H. From the appearance of the corresponding negative ions and threshold measurements this fundamental quantity has been deduced. In the particular case of C2-, the production of the negative ion in an electronically excited state has been put forward for the first time. Dissociation energies of the same diatomic and triatomic negative ions have been deduced and compared with this same magnitude in neutral and positive ionic species. [less ▲]

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