References of "Locht, Robert"
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See detailThe Dissociative Ionization of Carbon Dioxide below 21.22 eV. A high Resolution PIPECO spectroscopic investigation.
Locht, Robert ULg

in International Journal of Mass Spectrometry and Ion Processes (1995), 148

The photoion-photoelectron spectrum of O+, CO+ and CO2+ has been investigated under high resolution conditions. The O+ ion production is found not to be restricted to the CO2+ (C2Sigma+/g,0,0,0 ... [more ▼]

The photoion-photoelectron spectrum of O+, CO+ and CO2+ has been investigated under high resolution conditions. The O+ ion production is found not to be restricted to the CO2+ (C2Sigma+/g,0,0,0) predissociation. The (0,1,0) and (1,0,0) levels are clearly shown to be involved. The CO+ ion production involves all the vibrational states reached in the Franck-Condon region, i.e. up to (2,0,1) at 19.94 eV. The CO2+ molecular ion does not survive the predissociation in the entire range covered in the present work. [less ▲]

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See detailPhotoionization Dynamics of Mono- and Difluoroethylenes.
Leyh, Bernard ULg; Locht, Robert ULg; Hottmann, K. et al

Book published by Berliner Elektronen Speicherring für Synchrotron Strahlung m.b.H (1995)

Using synchrotron radiation, the threshold photoelectron spectrum and vibrationally resolved CIS-spectra have been recorded between 10-28 eV photon energy for C2H3F and 1,1-C2H2F2.

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See detailResonant Autoionization in Vinylchloride between 10-12 eV.
Locht, Robert ULg; Leyh, Bernard ULg; Hottmann, K. et al

Book published by Berliner Elektronen Speischerring für Synchrotron Strahlung m.b.H (1995)

The threshold photoelectron spectrum of Vinylchloride has been recorded using synchrotron radiation. The attention is focussed on the abundant fine structure between 10-12 eV and has been assigned to ... [more ▼]

The threshold photoelectron spectrum of Vinylchloride has been recorded using synchrotron radiation. The attention is focussed on the abundant fine structure between 10-12 eV and has been assigned to vibrational autoinization. [less ▲]

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See detailChemical Reactions in the Cluster Ions of 1,1-Difluoroethene and Argon.
Güthe, F.; Jochims, H.-W.; Leyh, Bernard ULg et al

Book published by Berliner Elektronen Speicherring für Synchrotron Strahlung m.b.H (1995)

The preparation conditions of 1,1-difluoroethene-Ar clusters has been investigated by photoionization using synchrotron radiation. The nature of the products has been identified by a quadrupole mass ... [more ▼]

The preparation conditions of 1,1-difluoroethene-Ar clusters has been investigated by photoionization using synchrotron radiation. The nature of the products has been identified by a quadrupole mass spectrometer. [less ▲]

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See detailStatistical and Non-statistical Reactions in Energy Selected Fluoromethane Ions.
Weitzel, K.-M.; Güthe, F.; Mähnert, J. et al

in Chemical Physics (1995), 201

The unimolécular reactions of the fluoromethane ion have been investigated by the threshold photoelectron photoion coincidence technique (TPIPECO). The breakdown curves have been measured in the energy ... [more ▼]

The unimolécular reactions of the fluoromethane ion have been investigated by the threshold photoelectron photoion coincidence technique (TPIPECO). The breakdown curves have been measured in the energy range between the adiabatic ionization potential of 12.53 eV and 21 eV. In this enery range the formation of the CH2F+, CHF+, CH2+, CH3+, and CF+ fragment ions is observed. The appearance energies (AE) for these ions at 300K are 13.2, 13.91, 13.93, 14.51 and <17.7 eV respectively. The 0K threshold energy for the formation of CH2F+ ions is 13.37 eV. Two different pathways for the unimolecular reaction of the fluoromethane ion can be distinguished.The reaction proceeding through the electronic ground state of the ion is entirely statistical. In contrast to this the reaction occurring through the first electronic excited state shows non-statistical behaviour. The two pathways are distinguished via the kinetic energy released in the respective dissociation channels. While all thermodynamically allowed reaction channels are observed on the ion ground state potential, the first excited state seems to decay predominantly by F loss reaction. [less ▲]

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See detailThe Dissociative Ionization of C2H2. The C+, C2+ and CH2+ Dissociation Channels. The Vinylidene Ion as a Transient?
Locht, Robert ULg; Davister, M.

in Chemical Physics (1995), 195

The dissociative electroionization of C2H2 has been investigated in the C+, C2+ and CH2+ dissociation channels. Both the translational energy and the appearance energies have been measured. The kinetic ... [more ▼]

The dissociative electroionization of C2H2 has been investigated in the C+, C2+ and CH2+ dissociation channels. Both the translational energy and the appearance energies have been measured. The kinetic energy versus appearance energy diagrams related to these species are discussed in detail and dissociation mechanisms are proposed for all observed onset energies. For the three ionic species, the dissociation pathways leading to the fragmentation of C2H2+ into C+, C2+ and CH2+ successively have to run very likely over an isomerization mechanism of the molecular ion. The isomeric vinylidene structure could be the most probable intermediate. [less ▲]

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See detailThe appearance energy of C2H+ from C2H2 revisited. A Photoion-Photoelectron Coincidence Spectroscopic Determination.
Servais, Christian ULg; Locht, Robert ULg

in Chemical Physics Letters (1995), 236

The dissociative ionization of C2H2 in the C2H+-producing channel has been reconsidered. The photoion-photoelectron coincidence (PIPECO) technique has been used. The C2H+/e coincidence rate has been ... [more ▼]

The dissociative ionization of C2H2 in the C2H+-producing channel has been reconsidered. The photoion-photoelectron coincidence (PIPECO) technique has been used. The C2H+/e coincidence rate has been recorded between 16.2 and 21.2 eV. The lowest appearance energy determined for C2H+ is 17.35+/-0.04 eV. A second appearance energy is measured at 18.40+/-0.04 eV. At both energies ethynyl ions are produced through a predissociation mechanism at the expense of the C2H2+(A2Ag) state at 17.35 eV and C2H2+(B2Sigma+/g) at 18.40 eV. These results are in good agreement with the most recent TPIPECO experiments and dissociative electroionization results. This comparison leads to the exclusion of any contribution of autoionization phenomena to the C2H+ ion production between 16.2 and 21.2 eV. Investigations of C2H+ through the ion-pair formation channel (and dissociative electron attachment producing C2H- and H-) in C2H2 are reported and its contribution to C2H+ ion production below 17.3 eV must be discarded. [less ▲]

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See detailThe Dissociaitve Ionization of C2H2 and C2D2. The [CH(CD)]+ dissociaiton channel. The H(D)C-C(D)H Binding Energy.
Davister, M.; Locht, Robert ULg

in Chemical Physics (1995), 191

The dissociative electroionization of C2H2(C2D2) has been investigated in the CH+(CD+) dissociation channel. The translational energy distribution of the fragment ion has been examined as a function of ... [more ▼]

The dissociative electroionization of C2H2(C2D2) has been investigated in the CH+(CD+) dissociation channel. The translational energy distribution of the fragment ion has been examined as a function of the electron energy between 20 and 99 eV. The first differentiated ionization efficiency curve has been measured for KE(CH+)=0.0-6.0 eV. Threshold energies of CH+ and CD+ have been measured and the effect of isotopic substitution is discussed. For the lowest onset of both CH+ and CD+, and from the kinetic energy measurements, the C-C bond strength has been derived, i.e. D(HC-CH)=9.83+/-0.10 eV. Higher appearance energies are assigned and reaction mechanisms are proposed. Above 34 eV electron energy, the CH+ ions carrying 2.0-5.5 eV kinetic energy are produced through Coulomb explosion of (C2H2)2+ states. [less ▲]

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See detailThe Dissociative Electroionization of C2H2, C2D2 and C2HD. Investigation of the [C2H(D)]+ and [H(D)]+ Dissociation Channels. The (D)H-C2H(D) binding energy.
Davister, M.; Locht, Robert ULg

in Chemical Physics (1994), 189

The dissociative electroionization of C2H2 in the H+ and C2H+ dissociation channels has been extensively investigated in C2H2 and C2D2. The kinetic energy distributions and ionization efficiency curves of ... [more ▼]

The dissociative electroionization of C2H2 in the H+ and C2H+ dissociation channels has been extensively investigated in C2H2 and C2D2. The kinetic energy distributions and ionization efficiency curves of both species were examined in detail. The H(D)+ ion shows its lowest onset energy at 18.93+/-0.2 eV whereas the C2H+ is produced at 17.30+/-0.11 eV. For the H+-producing channel the kinetic energy (KE) versus the appearance energy (AE) diagram is obtained, extensively discussed and the bond dissociation energy D(H-C2H)= 5.33+/-0.23 eV is estimated. This value is compared and discussed with respect to the values found in the literature. Predissociation and dissociative autoionization are the dominant H+-producing mechanisms. At high electron energies doubly ionized states of C2H2 are involved. For C2H+, beside the threshold at 17.30+/0.11 eV a new onset at 18.27+/0.10 eV is observed. The ionization efficiency of the doubly ionized molecular ion is observed for the first time in C2HD isotopic species. [less ▲]

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See detailThe OCS Molecule. The Photoabsorption Spectrum. The Threshold Photoelectron and CIS-photoelectron Spectra.
Locht, Robert ULg; Hottmann, K.; Baumgärtel, H.

Book published by Berliner Elektronen Speicherring für Synchrotron Strahlung m.b.H (1994)

Using synchrotron radiation the threshold-, the CIS- and the 21.22 eV-photoelectron spectra are reported. This investigation has been completed by recording the VUV photoabsorption spectrum.

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See detailThe Dissociative Ionization of C2H2. The H-C2H Binding Energy.
Davister, M.; Locht, Robert ULg

in Cornides, I.; Horvath, G.; Veakey, K. (Eds.) Book of Abstracts. Advances in mass spectrometry Volume 13 (13th IMSC Budapest 94) (1994)

The dissociative electroionization measurements on C2H+/C2H2 are reported. Kinetic energy and appearance energies are measured. On these data the D(H-C2H) binding energy is deduced.

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See detailThe Absorption Spectrum and the Threshold- and CIS-photoelectron Spectra of CS2.
Locht, Robert ULg; Hottmann, K.; Denzer, W. et al

Book published by Elektronen Speicherring für Synchrotron Strahlung m.b.H (1993)

Using synchrotron radiation the VUV photoabsorption, the threshold photoelectron and the CIS-photoelctron spectra are measured between 9.9-17.9 eV and are briefly discussed.

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See detailDissociative Electroionization Study in Acetylene. The Production of CH(D)+ in C2H2 and C2D2.
Davister, M.; Locht, Robert ULg

in Andersen, T.; Fastrup, B.; Folkmann, F. (Eds.) et al Electronic and Atomic Collisions: Abstract of contributed Papers. (1993)

An extensive study of the dissociative electroionization of C2H2(D2) in the CH(D)+ producing channel is reported. The translational energy-versus-appearance energy diagram reveals 9 CH+-producing ... [more ▼]

An extensive study of the dissociative electroionization of C2H2(D2) in the CH(D)+ producing channel is reported. The translational energy-versus-appearance energy diagram reveals 9 CH+-producing processes involving C2H2+ and (C2H2)2+ ionic states and is discussed in detail. [less ▲]

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See detailThe Appearance of C2H3+ Ions from C2H3F by non-resonant Photoionization. A Translational Energy Surprisal Analysis.
Momigny, J.; Locht, Robert ULg

in Chemical Physics Letters (1993), 211(2,3), 161-165

It is shown that for a photon energy of 16.85 eV the translational energy surprisal of the C2H3++F dissociation products from C2H3F+ has a bimodal behaviour. The possibility of considering the bimodal ... [more ▼]

It is shown that for a photon energy of 16.85 eV the translational energy surprisal of the C2H3++F dissociation products from C2H3F+ has a bimodal behaviour. The possibility of considering the bimodal surprisal as due to the superposition of two translational energy distributions is consistent with the theoretical assumption of the concurrence of two channels in this dissociation process. The characteristics of these distributions, i.e. the energy width and the relative abundance, are in agreement with the results of an ab initio quantum-mechanical calculation of the dynamics of this dissociation. They are consistent with the simultaneous occurrence of a statistical dissociation of C2H3F+(X2A') into C2H3+(X1A') and an isolated state dissociation of C2H3F+(C2A") into C2H3+(a3A"). Negative lambda values obtained for the surprisal of both these distributions indicate an inversion of the translational level population of the dissociation products. [less ▲]

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See detailThe Threshold Photoelectron Spectrum of NH3.
Locht, Robert ULg; Hottmann, K.; Hagenow, G. et al

in Chemical Physics Letters (1992), 190(1,2), 124-129

Using synchrotron radiation, we have investigated the threshold photoelectron spectrum of NH3 between 10-30 eV photon energy. In contrast to the He(I)-photoelectron spectrum, the threshold photoelectron ... [more ▼]

Using synchrotron radiation, we have investigated the threshold photoelectron spectrum of NH3 between 10-30 eV photon energy. In contrast to the He(I)-photoelectron spectrum, the threshold photoelectron spectrum shows three bands between 10 and 21 eV. The first band is dominated by the vibrational autoionization of the 5a1, the 6a1 and the 6pe Rydberg series. Between the first and second bands a new contribution, starting at 13.26 eV, is assigned to the autoionization of (a) member(s) of Rydberg series converging to the e-1 ionization continuum. Its (their) autoionization populates the upper vibrational levels of the NH3+ (X2A1) state. From about 14.5 eV the A2E band structures are identified. However, differences between the A2E band shapes in the He(I)- and the threshold photoelectron spectra suggest that very likely autoionization contributions are involved in the latter spectrum. These phenomena could play a role in the production of the NH2+ and NH+ fragment ions. The last very weak band, at about 25 eV in the photoelectron spectrum is assigned to the NH3+(B2A1) state. [less ▲]

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See detailPhotoionization Mass Spectrometry of Kinetic Energy-selected ions. The Translational Energy Distribution of N+/N2 in the Inner-shell Ionization energy range.
Locht, Robert ULg; Denzer, W.; Rühl, E. et al

in Chemical Physics (1992), 160

An ion retarding potential difference (IRPD) method has been used to investigate the ion yield and the kinetic energy distributions of N+/N2 produced by photoionization mass spectrometry using synchrotron ... [more ▼]

An ion retarding potential difference (IRPD) method has been used to investigate the ion yield and the kinetic energy distributions of N+/N2 produced by photoionization mass spectrometry using synchrotron radiation. Photoion yield curves of energy selected N+ ions are deduced. Translational energy distributions of N+ at the energies of the N(1s)->pi*, N(1s)->(nl)1 and above the N(1s)-1 threshold are determined. Comparison is made with previous photoion-photoelectron coincidence work using time-of-flight (TOF) measurements. [less ▲]

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See detailCore Level Excitation of Atomic and Molecular Clusters.
Rühl, E.; Schmale, C.; Jochims, H. W. et al

in Beswick, A. (Ed.) Synchrotron Radiation and Dynamic Phenomena. (1992)

Core level excitation of weakly bonded atomic and molecular species is reported. Excitations into unoccupied orbitals with valence and Rydberg character as well as into the corresponding K- and L-continua ... [more ▼]

Core level excitation of weakly bonded atomic and molecular species is reported. Excitations into unoccupied orbitals with valence and Rydberg character as well as into the corresponding K- and L-continua are compared with the isolated and condensed species. Core level excitation of clusters is also accompagned with extensive fragmentation of singly and doubly charged clusters. Coincidence techniques such as photoelectron-photoion-coincidences (PEPICO) and photoion-photoion-coincidence (PIPICO) are used to study the photochemical fragmentation pathways of core excited clusters. Kinetic energy releases related to charge separation of cluster dications (Coulomb explosion) are derived from PIPICO spectra. The fragmentation energetics is discussed in relation to cluster dication threshold energies. [less ▲]

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See detailThreshold- und CIS-Photoelektronenspektren von SO2
Hottmann, K.; Baumgärtel, H.; Locht, Robert ULg

Book published by Berliner Elektronen Speicherring für Synchrotron Stahlung m.b.H (1992)

The threshold- and CIS-photoelectron spectrum of SO2 has been measured using synchrotron radiation. It is compared to the He(I)-photoelectron spectrum measured with the same instrument under the same ... [more ▼]

The threshold- and CIS-photoelectron spectrum of SO2 has been measured using synchrotron radiation. It is compared to the He(I)-photoelectron spectrum measured with the same instrument under the same conditions. Several additional vibrational fine structures are observed between the first and the second bands. These are interpreted in terms of autoionization also detected in the CIS-spectra. At higher photon energies, band maxima are measured at 19.2 eV, 20.6 eV and 23.5 eV. [less ▲]

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See detailIon Translational Energy Distributions from Inner-shell Dissociative ionization of N2O, NH3 and SF6.
Locht, Robert ULg; Leyh, Bernard ULg; Jochims, H. W. et al

Book published by Berliner Elektronen Speicherring für Synchrotron Strahlung m.b.H (1992)

The IRPD method is applied to the dissociative ionization in the inner-shell ionization region for NO+, N2+, O+, N+ and N++/N2O. Particular attention has been focussed on the production and ion kientic ... [more ▼]

The IRPD method is applied to the dissociative ionization in the inner-shell ionization region for NO+, N2+, O+, N+ and N++/N2O. Particular attention has been focussed on the production and ion kientic energy distribution of H+/NH3. [less ▲]

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See detailPhotoionization of NH3 and its Isotopomers between 10 and 12 eV.
Locht, Robert ULg; Leyh, Bernard ULg; Denzer, W. et al

in Kistemaker, P. G.; Nibbering, N. M. (Eds.) Advances in Mass Spectrometry: Proceedings of the 12th IMSC, Amsterdam (International Mass Spectrometry Conference 26-30 August 1991): Book of Abstracts. (1991)

The photoionization of NH3 and its isotopomers is measured between 10-12 eV photon energy by using synchrotron radiation. The abundant autoionization structure observed in the ionization efficiency curves ... [more ▼]

The photoionization of NH3 and its isotopomers is measured between 10-12 eV photon energy by using synchrotron radiation. The abundant autoionization structure observed in the ionization efficiency curves is analyzed. [less ▲]

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