References of "Momigny, J"
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See detailThe Appearance of CH3+ Ions from Methyl Halides by resonant photoionization. A translational energy surprisal analysis. Part I. CH3F.
Momigny, J.; Locht, Robert ULg

in Chemical Physics (1996), 206

A surprisal analysis has been applied to the translational energy distribution (TED) of CH3++F from CH3F giving rise to a new and deeper insight into the dissociation dynamics involved in the process. For ... [more ▼]

A surprisal analysis has been applied to the translational energy distribution (TED) of CH3++F from CH3F giving rise to a new and deeper insight into the dissociation dynamics involved in the process. For both the 16.5 eV and 21.22 eV photon energies used, the direct population at different energy levels of the B2E state of CH3F+ which is radiationlessly coupled to the repulsive CH3F+(A2A1) state, gives rise to wide and negatively surprised total TEDs. At both energies they have to be ascribed to severe limitations in the vibrational excitation of CH3+. Additionally, in the case of 21.22 eV photons, a non-statistical expression has to be used to account for the density of translational states. At both photon energies, the population of the CH3F+ electronic states through autoionization of Rydberg states accounts for (i) the concurrent appearance of TEDs governed by a pure RRKM behavour and (ii) the positively surprised TEDs where the angular momentum conservation plays an important role. At 16.85 eV photon energy the distributions are assigned to CH3F+ (X2E)->CH3+ (X1A'1)+F. At 21.22 eV photon energy, doubly excited electronic states of CH3F+ are assumed to take part and they are correlated with CH3+ (3A")+F channel. [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 Dissociative Electroionization of NH3 and ND3. A detailed Study of its five Dissociation Channels.
Locht, Robert ULg; Momigny, J.

in Longevialle, P. (Ed.) Advances in Mass Spectrometry. Volume 11A. (1988)

A general view of the results obtained for the dissociative ionization by electron impact on NH3 are presented. All five dissociation channels for the decomposition of the singly ionized NH3+ and the ... [more ▼]

A general view of the results obtained for the dissociative ionization by electron impact on NH3 are presented. All five dissociation channels for the decomposition of the singly ionized NH3+ and the doubly ionized (NH3)2+ are reported. [less ▲]

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See detailThe Dissociative Electroionization of Ammonia and Ammonia-d3. I. The NH+ and NH2+ dissociation channels.
Locht, Robert ULg; Servais, Christian ULg; Ligot, M. et al

in Chemical Physics (1988), 123

The dissociative electroionization of NH3 (ND3) in the NH2+ (ND2+) and NH+(ND+) dissociation channels is investigated in the 15-50 eV electron energy range. The translational energy distributions of ND2 ... [more ▼]

The dissociative electroionization of NH3 (ND3) in the NH2+ (ND2+) and NH+(ND+) dissociation channels is investigated in the 15-50 eV electron energy range. The translational energy distributions of ND2+ (NH2+) exhibit several components whereas NH+ only shows a continuous broad distribution. For both ions a kinetic energy-versus-appearance energy diagram is obtained and discussed. The predissociation of the Jahn-Teller split NH3+(A2E) state produces both ions at their lowest threshold. At higher energies dissociative autoionization (in the 22 eV region), dissociative ionization through the NH3+(B2A1) state (in the 24-30 eV region) as well as by Coulomb repulsion of doubly ionized states (in the 35-50 eV region) produce NH2+(ND2+) and NH+ with large amounts of kinetic energy. Some arguments are brought forward to indicate that the former value of the NH2-H dissociation energy is overestimated. [less ▲]

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See detailThe Dissociative Electroionization of Ammonia and Ammonia-d3. II. The H+ and H2+ Dissociation Channels.
Locht, Robert ULg; Servais, Christian ULg; Ligot, M. et al

in Chemical Physics (1988), 125

The dissociative electroionization of NH3(ND3) in the H(D)+ and H(D)2+ dissociation channels is investigated in the 18-50 eV electron energy range. The H(D)+ translational energy distribution spectrum ... [more ▼]

The dissociative electroionization of NH3(ND3) in the H(D)+ and H(D)2+ dissociation channels is investigated in the 18-50 eV electron energy range. The H(D)+ translational energy distribution spectrum shows several components and that of H(D)2+ is continuous. The thermal energy component of the latter distribution is entirely ascribed to H2+/H2. For both ions the kinetic energy-versus-appearance energy diagram is obtained and discussed. The H+ ion at the lowest onset is probably formed at the expense of the NH3+(A2E) state. In the 22.5 eV electron energy range both H+ and H2+ are formed by dissociative autoionization. Evidence is also brought for H+ and H2+ formation at 22.5 eV and 26.5 eV through spontaneous decomposition of NH2+. Above 35 eV dissociation of doubly ionized states by Coulomb repulsion is mainly involved. [less ▲]

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See detailAbout the Double Ionization of NH3 and CO2. A Comparison between Photoionization and Electron Impact.
Locht, Robert ULg; Davister, M.; Momigny, J. et al

Book published by Berliner Elektronen Speicherring für Synchrotron Strahlung m.b.H. (BESSY) (1988)

The photoionization efficiency curves of (NH3)2+ and (CO2)2+ have been recorded and threshold energies have been measured. The results are compared with those obtained by electron impact.

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See detailThe Dissociative Electroionization of Ammonia and Ammonia-d3. III. The N+ Dissociation Channel. General Conclusions about the Dissociation of NH3+.
Locht, Robert ULg; Momigny, J.

in Chemical Physics (1988), 127

The dissociative ionization of NH3 is investigated in its N+ dissociation channel in the 20-50 eV electron energy range. Both the translational energy distribution and the appearance energies are measured ... [more ▼]

The dissociative ionization of NH3 is investigated in its N+ dissociation channel in the 20-50 eV electron energy range. Both the translational energy distribution and the appearance energies are measured. The kinetic energy-versus-appearance energy plot reveals seven N+ producing processes. Near the onset (22.5-24.0 eV) dissociative autoionization occurs whereas direct dissociative ionization produces N+ in the 24.5-30 eV range. Above 35 eV mainly N+/H+ ion pairs are formed at the expense of doubly ionized states. The dissociative electroionization work on NH3 being completed a review of the results is presented. [less ▲]

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See detailThe double Ionization of Ammonia. Its Dissociation into the Doubly Ionized Fragment N2+.
Locht, Robert ULg; Momigny, J.

in Chemical Physics Letters (1987), 138(5), 391-396

The double ionization and dissociation of NH3 into the doubly ionized fragment N2+ is investigated by electron impact. Two double ionization energies of NH3 are directly measured at 34.8+/-0.2 eV and 39.4 ... [more ▼]

The double ionization and dissociation of NH3 into the doubly ionized fragment N2+ is investigated by electron impact. Two double ionization energies of NH3 are directly measured at 34.8+/-0.2 eV and 39.4+/-0.5 eV. A third critical energy observed at 66 eV is assigned to a (NH3)2+ state whose ionization energy is at 61 eV. Two appearance energies are observed for the N2+ ion at 65.9+/-1.7 eV and 74.3+/-2.6 eV. The translational energy distribution of N2+ is shown to be essentially thermal. The former onset is ascribed to the dissociation of the 61 eV state of (NH3)2+, the latter originates from the doubly ionized (NH3)2+ state at 70 eV. [less ▲]

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See detailA Mass Spectrometric Photoionization Study of CH3F. The CH2+, CH3+ and CH2F+ Ion Formation.
Locht, Robert ULg; Momigny, J.; Rühl, E. et al

in Chemical Physics (1987), 117

The decay of CH3F+ in the CH2+, CH3+ and CH2F+ dissociation channels has been investigated by photoionization mass spectrometry using synchrotron radiation in the energy range 10-25 eV. The ... [more ▼]

The decay of CH3F+ in the CH2+, CH3+ and CH2F+ dissociation channels has been investigated by photoionization mass spectrometry using synchrotron radiation in the energy range 10-25 eV. The photoabsorption curve of CH3F and the ionization efficiency curves of CH2+, CH3+ and CH2F+ as well as the kinetic energy-versus-appearance energy diagram for CH3+ were recorded. For the three fragment ions dissociative autoionization is a prominent formation process. Direct dissociative ionization is observed for the same ions through the decomposition of the CH3F+(A2A1+B2E) states at 16.1 eV as well as presumably of the C2A1 state at about 22.5 eV. [less ▲]

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See detailThe Dissociative Photoionization of O2 and N2O.
Locht, Robert ULg; Hagenow, G.; Rühl, E. et al

Book published by Berliner Elektronen Speicherring für Synchrotron Strahlung m.b.H. (BESSY) - Jahresbericht/Annual Report (1987)

The dissociative photoionization of O2 and N2O is investigated using synchrotron radiation. The results on the O+ and NO+ dissociation channels are reported.

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See detailThe Dissociative Ionization of CH3F. A Mass Spectrometric Photoionization study using Synchrotron Radiation.
Locht, Robert ULg; Rühl, E.; Momigny, J. et al

in Gilbody, H. B.; Newell, W. R.; Read, F. H. (Eds.) et al Electronic and Atomic Collisions: Abstracts of Contributed Papers. (1987)

The dissociation channel of CH3F+hnu->CH3++F has been investigated by photoionization using synchrotron radiation. The kinetic energy-versus-appearance energy diagram of CH3+ has been reported and ... [more ▼]

The dissociation channel of CH3F+hnu->CH3++F has been investigated by photoionization using synchrotron radiation. The kinetic energy-versus-appearance energy diagram of CH3+ has been reported and analyzed. [less ▲]

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See detailThe Dissociative Photoionization of CH3F.
Locht, Robert ULg; Rühl, E.; Momigny, J. et al

Book published by Berliner Elektronen Speicherring für Synchrotron Strahlung m.b.H. (BESSY) (1987)

The kinetic energy distributions of CH3+/CH3F are measured at different wavelengths using monochromatized synchrotron radiation. The ionization efficiency curves of CH3+ are measured for different kinetic ... [more ▼]

The kinetic energy distributions of CH3+/CH3F are measured at different wavelengths using monochromatized synchrotron radiation. The ionization efficiency curves of CH3+ are measured for different kinetic energies. The resulting kinetic energy-versus-appearance energy is reported. [less ▲]

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See detailThe Dissociative Electroionization of NH3. The NH+ Dissociation Channel.
Locht, Robert ULg; Servais, Christian ULg; Ligot, M. et al

in Gilbody, H. B.; Newell, W. R.; Read, F. H. (Eds.) et al Electronic and Atomic Collisions: Abstracts of Contributed Papers. 15th International Conference on the Physics of Electronic and Atomic Collisions. Brighton, United Kingdom, 1987. (1987)

The dissociative electoionization efficiency of Nh3 in the NH+ channel is reported. The kinetic energy of this fragment ion is measured as a function of the impinging electron energy. Several dissociation ... [more ▼]

The dissociative electoionization efficiency of Nh3 in the NH+ channel is reported. The kinetic energy of this fragment ion is measured as a function of the impinging electron energy. Several dissociation limits are detected. [less ▲]

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See detailA versatile low-cost Automation System for an Electroionization Experiment.
Servais, Christian ULg; Locht, Robert ULg; Momigny, J.

in International Journal of Mass Spectrometry and Ion Processes (1986), 74

A cheap complete automation system designed for an electoionization experiment is described. This system is based on a Sinclair ZX Spectrum computer and a modular architecture. The control program and ... [more ▼]

A cheap complete automation system designed for an electoionization experiment is described. This system is based on a Sinclair ZX Spectrum computer and a modular architecture. The control program and general building blocks diagrams are discussed and give a general idea of how to build modules or procedures adapted to different applications. [less ▲]

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See detailTranslational Energy Disposal and Mechanisms of Unimolecular Dissociative Photoionization with He(I) and Ne(I) Resonance Lines. A Surprisal Ananlysis of the CH3F->CH3++F Process.
Momigny, J.; Locht, Robert ULg; Caprace, G.

in International Journal of Mass Spectrometry and Ion Processes (1986), 71

The He(I) and Ne(I) photoions translational energy spectra of CH3+ from CH3F were measured. At both wavelengths, the translational energy spectrum is made of two components. Their surpisal analysis shows ... [more ▼]

The He(I) and Ne(I) photoions translational energy spectra of CH3+ from CH3F were measured. At both wavelengths, the translational energy spectrum is made of two components. Their surpisal analysis shows two distinct behaviours: (i) the low energetic and narrow component exhibits a positive slope, whereas (ii) the high energetic and widely spread component is characterized by a negative slope. Furthermore, when He(I) is used, the high translational energy distribution shows a multimodal surprisal. These observations as well as the origin of both distributions are discussed. [less ▲]

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See detailThe Dissociative Ionization of Methyl Fluoride. The formation of CH2+ and CH3+.
Locht, Robert ULg; Momigny, J.

in International Journal of Mass Spectrometry and Ion Physics (1986), 71

The decay of ionized CH3F was investigated in the CH2+ and CH3+ dissiciation channels by electronionization and fixed wavelength photoionization using HeI and NeI resonance lines. The translational energy ... [more ▼]

The decay of ionized CH3F was investigated in the CH2+ and CH3+ dissiciation channels by electronionization and fixed wavelength photoionization using HeI and NeI resonance lines. The translational energy spectra, ionization efficiency curves and kinetic energy-versus-appearance enegy diagrams of both ions were measured. Although dissociative autoionization is the prominent dissociation mechanism for the appearance of CH2+ and CH3+, direct dissociative ionization is observed for CH2+ at 23.4 eV and for CH3+ at 16.5 eV. [less ▲]

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See detailMechanism for the Appearance of H+ by Electroionization of CH4. A Surprisal Analysis.
Momigny, J.; Locht, Robert ULg; Caprace, G.

in Chemical Physics (1986), 102

Previous experimental results on the threshold energy and on the energy range of the first wide translational energy distribution of H+, resulting from the electron impact on CH4, are interpreted. The ... [more ▼]

Previous experimental results on the threshold energy and on the energy range of the first wide translational energy distribution of H+, resulting from the electron impact on CH4, are interpreted. The translational energy surprisal of this distribution has been evaluated with respect to a statistically calculated one. The surprisal plot shows a fourth power dependence on fT with a negative slope associated with a large DeltaS/exc value of about 4 eu. An "a priori" calculated P(ET/E) distribution, including four constraints, fits fairly well the observed translational energy distribution. [less ▲]

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See detailAbout the Kinetic Energy Spectra of Fragment Ions. A comparison between Electroionization and fixed-wavelength Photoionization.
Locht, Robert ULg; Momigny, J.

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

The HeI and NeI translational energy spectra have been recorded for NO+/N2O and CH3+/CH3F. The marked difference between the two spectra for NO+ is related to the NeI-A2Sigma+ photoelectron spectrum. Both ... [more ▼]

The HeI and NeI translational energy spectra have been recorded for NO+/N2O and CH3+/CH3F. The marked difference between the two spectra for NO+ is related to the NeI-A2Sigma+ photoelectron spectrum. Both spectra of CH3+ show two components, i.e. a thermal peak and a high energy distribution. As the energetic ions are ascribed to the decomposition of the CH3F+(2E+2A1) states the thermal ions could be interpreted by the dissociation of the CH3F+(X2E) state. [less ▲]

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See detailA Dissociative Electroionization Study of Nitrous Oxide. The O+ and N+ Dissociation channels.
Olivier, J. L.; Locht, Robert ULg; Momigny, J.

in Chemical Physics (1984), 84

After the investigation of the decay of N2O into NO+ and N2+ the dissociation channels leading to O+ and N+ are examined by electroionization using ion kinetic energy and mass analysis. Appearance ... [more ▼]

After the investigation of the decay of N2O into NO+ and N2+ the dissociation channels leading to O+ and N+ are examined by electroionization using ion kinetic energy and mass analysis. Appearance energies of O+ and N+ are measured as a function of the kinetic energy of the fragment ions. Predissociation is the main mechanism for ion production in both channels. In the O+ decay channel the 4Sigma- state is an important intermediate. The neutral N2(X1Sigma+/g) mainly appears vibrationally excited. In the N+ dissociation channel, 2Pi states have to play an important role by predissociating the N2O(C2Sigma+) state and the higher-lying doubly excited states of N2O+. [less ▲]

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See detailThe Dissociative Ionization of Nitrous Oxide. A comparison between Electroionization and HeI and NeI Photoionization.
Locht, Robert ULg; Caprace, G.; Momigny, J.

in Chemical Physics Letters (1984), 111

The photoelectron spectrum of N2O and the kinetic energy distributions of NO+, N2+, O+ and N+ have been recorded with HeI and NeI resonance lines. At 21.22 eV the distributions are similar to those ... [more ▼]

The photoelectron spectrum of N2O and the kinetic energy distributions of NO+, N2+, O+ and N+ have been recorded with HeI and NeI resonance lines. At 21.22 eV the distributions are similar to those observed by electroionization at comparable energy. The NeI resonance line produces O+ and NO+ ions. Their respective kinetic energy distributions are related to the change induced in the N2O+(A2Sigma+) photoelectron band excited by the NeI resonance line. [less ▲]

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