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See detailPhotoionization Mass Spectrometry of Kinetic energy-selected ions. An Ion Retarding Potential Difference method applied to NO+ and O+ from N2O.
Locht, Robert ULg; Hagenow, G.; Hottmann, K. et al

in Chemical Physics (1991), 151

A new method is described to obtain photoionization efficiency curves of kinetic energy-selected fragment ions. The method is tested and discussed in the case of the dissociative photoionization yields of ... [more ▼]

A new method is described to obtain photoionization efficiency curves of kinetic energy-selected fragment ions. The method is tested and discussed in the case of the dissociative photoionization yields of NO+ and O+ from N2O. The attention is focussed on the dissociative autoionization processes in the threshold region, in the Franck-Condon region of the N2O(A2Sigma+) state and in the Franck-Condon gap between the A2Sigma+ and B2Pi states. [less ▲]

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See detailCore Level Excitation in molecular Clusters.
Rühl, E.; Schmale, C.; Baumgärtel, H. et al

Book published by Berliner Elektronen Speicherring für Synchrotron Strahlung m.b.H (1991)

The photoionization of CO at the C-Kedge and that of its dimer are measured. The photodissociation of the cluster ion is investigated by PEPICO and PIPICO techniques.

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See detailVibrational Autoionization in NH3 and its Isotopomers in the 10-12 eV photon energy range.
Locht, Robert ULg; Leyh, Bernard ULg; Denzer, W. et al

in MacGillivray, W. R.; McCarthy, I. E.; Standage, M. C. (Eds.) ICPEAC Abstracts (International Conference on the Physics of Electronic and Atomic Collisions) (1991)

The photoionization efficiency curves of the four isotopomers of NH3 have been recorded using synchrotron radiation. The abundant fine structure has been interpreted in terms of vibrational structure of ... [more ▼]

The photoionization efficiency curves of the four isotopomers of NH3 have been recorded using synchrotron radiation. The abundant fine structure has been interpreted in terms of vibrational structure of Ryberg series which autoionize. [less ▲]

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See detailThe Photoionization of Ammonia revisited. The Vibrational Autoionization of NH3 and its three Isotopomers in the 10-12 eV photon energy range.
Locht, Robert ULg; Leyh, Bernard ULg; Denzer, W. et al

in Chemical Physics (1991), 155

The photoionzation efficiency curves of NH3 and its three isotopomers have been investigated in the photon energy range of the first ionized state. From the analysis of the corresponding vibrational ... [more ▼]

The photoionzation efficiency curves of NH3 and its three isotopomers have been investigated in the photon energy range of the first ionized state. From the analysis of the corresponding vibrational structure, wavenumbers and anharmonicity constants are deduced. The detailed investigation of the abundant autoionization structure tends to show the adiabatic ionization energy to be 10.072+/-0.010 eV for NH3, NH2D and NHD2 and 10.083+/-0.010 eV for ND3. All autoionization features were classified in vibrational progressions (nu2 bending mode) belonging to nasa1 (or nd) and npe (n=5, 6, 7) Rydberg series. Vibrational autoionization occurs through Delta v transitions up to -9. A qualitative analysis of the intensity distribution of these series strongly supports that transitions involving odd Delta v values are favoured. This observation can be understood by applying group theoretical considerations to the theory of vibrational autoionization. [less ▲]

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See detailThe Photoionization of Ammonia Revisited. The Autoionization in NH3 and its three Isotopomers in the 10-12 eV photon energy range.
Locht, Robert ULg; Leyh, Bernard ULg; Denzer, W. et al

Book published by Berliner Elektronen Speicherring für Synchrotron Strahlung m.b.H (1990)

The photoionization efficiency curves of NH3, NH2D, NHD2 and ND3 have been measured using synchrotron radiation. The fine structure has been interpreted in terms of vibrational autoionization.

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See detailThe vacuum Ultraviolet Photoabsorption and Photoelectron Spectroscopy of Fluoroethylenes. The 1,1-, cis- and trans-C2H2FCl.
Tornow, G.; Locht, Robert ULg; Kaufel, R. et al

in Chemical Physics (1990), 146

The vacuum ultraviolet absorption spectra of the three fluorochloroethene isomers were measured in the 6-13 eV photon energy range. Additionally, the HeI and NeI photoelectron spectra were recorded. The ... [more ▼]

The vacuum ultraviolet absorption spectra of the three fluorochloroethene isomers were measured in the 6-13 eV photon energy range. Additionally, the HeI and NeI photoelectron spectra were recorded. The assignment of the various photoelectron bands is based on MNDO calculations. The vaccum UV absorption spectral features were classified in terms of Rydberg series converging to the first and second ionization energy. Besides the typical pi-pi* transition, other valence transitions were observed and tentatively assigned. In the geminal isomer spectrum the dominant Rydberg series converge to the first ionization limit at 10.02 eV, in the cis and trans isomers the most intense Rydberg transitions converge to the second ionization energy at 11.87 and 12.03 eV respectively. The first ionization energies of these latter compounds, obtained by Rydberg series analysis, are 9.89 and 9.87 eV respectively. An assignment of the vibrational structure observed in both spectra is proposed. [less ▲]

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See detailThe Threshold Photoelectron Spectrum of NH3 in the 10-31 eV photon energy range.
Locht, Robert ULg; Hottmann, K.; Denzer, W. et al

Book published by Berliner Elektronen Speicherring für Synchrotron Strahlung m.b.H (1990)

The measurement of the threshold photoelectron spectrum of NH3 by using synchrotron radiation is reported for the first time. Several new bands are highlighted.

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See detailA new way to look at Photoionization Mass Spectrometry: an Ion Retarding Potential Difference Method.
Locht, Robert ULg; Rühl, E.; Hagenow, G. et al

in 9th International Conference on Vacuum Ultraviolet Radiation Physics: Program and Abstracts. (1989)

Photoionization efficiency curves of O+/O2 recorded at different ion retarding potential settings are measured with increments of 50 meV. From these data ion retarding potential difference ionization ... [more ▼]

Photoionization efficiency curves of O+/O2 recorded at different ion retarding potential settings are measured with increments of 50 meV. From these data ion retarding potential difference ionization efficiency curves are obtained. [less ▲]

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See detailAn Ion Retarding Potential Difference Method applied to Dissociative Photoionization Mass Spectrometry.
Locht, Robert ULg; Rühl, E.; Hagenow, G. et al

in Dalgarno, A.; Freund, R. S.; Lubell, M. S. (Eds.) et al 16th International Conference on the Physics of Electronic and Atomic Collisions: Abstract of Contributed Papers. (1989)

Dissociative photoionization of O2 has been investigated by using the ion retarding potential for the translational energy analysis of the O+ fragment. Synchrotron radiation is used as a light source ... [more ▼]

Dissociative photoionization of O2 has been investigated by using the ion retarding potential for the translational energy analysis of the O+ fragment. Synchrotron radiation is used as a light source. Ionization efficiency curves have been recorded at several retarding potential settings. [less ▲]

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

in Dalagarno, A.; Freund, R. S.; Lubell, M. S. (Eds.) et al 16th Internatioanl Conference on the Physics of Electronic and Atomic Collisions: Abstracts of Contributed Papers. (1989)

Using synchrotron radiation the double ionization of NH3 and CO2 is measured. The results are compared with those obtained by electron impact.

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See detailAbout the Double Ionization of Ammonia and Carbon Dioxide. A Comparison between Photoionization and Electron Impact.
Locht, Robert ULg; Davister, M.; Denzer, W. et al

in Chemical Physics (1989), 138

The double ionization of NH3 and CO2 is investigated by photoionization in the 30-60 eV photon energy range and electron impact from 30-100 eV. The lowest onset for (NH3)2+ formation, measured for the ... [more ▼]

The double ionization of NH3 and CO2 is investigated by photoionization in the 30-60 eV photon energy range and electron impact from 30-100 eV. The lowest onset for (NH3)2+ formation, measured for the first time by photoionization, is at 34.5+/-0.2 eV. By electron impact this threshold is 34.8+/0.2 eV. For (CO2)2+ this onset is measured at 37.5+/-0.1 eV by photoionization and at 38.0+/-0.1 eV by electron impact. Close to these onsets two double ionization energies are observed: 38.5+/-0.1 eV by photoionization and 39.5+/-0.2 eV by electron impact. These have probably to be ascribed to two different (CO2)2+ states. Higher-lying doubly ionized states of CO2 are detected in the 60-100 eV electron impact energy range. [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 detailThe Dissociative Photoionization of Ammonia. The Formation of NH2+, NH+ and N+.
Locht, Robert ULg; Hagenow, G.; Denzer, W. et al

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

The dissociative ionization of NH3 has been investigated by photoionization using synchrotron radiation. Appearance energies and the kinetic energy of NH2+, NH+ and N+ are reported.

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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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