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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 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 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 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 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 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 detailThe Dissociative Ionization of N2O by low energy Electron Impact: the N+ and N2+ Dissociation Channels.
Locht, Robert ULg; Olivier, J. L.; Beeckman, W. et al

in XII International Conference on the Physics of Electronic and Atomic Collisions: Abstracts of Contributed Papers. (1981)

The kinetic energy-versus-appearance energy diagram obtained for N+ and N2+ from N2O by electron impact 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 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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See detailThe Dissociative ionization of Nitrous Oxide. An Electroionization Study.
Olivier, J. L.; Locht, Robert ULg; Momigny, J.

in International Journal of Mass Spectrometry and Ion Physics (1984), 58

The dissociative electroionization of nitrous oxide into its four dissociation channels has been studied by a method using the kinetic energy and mass analysis. The formation of N2+, NO+, O+ and N+ are ... [more ▼]

The dissociative electroionization of nitrous oxide into its four dissociation channels has been studied by a method using the kinetic energy and mass analysis. The formation of N2+, NO+, O+ and N+ are discussed essentially in terms of predissociation of the ground and excited N2O+ states between 15 and 40 eV. In most cases the predissociating states are also identified. The present results are compared with those in the literature. [less ▲]

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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 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 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 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 detailLa dissolution pour justes motifs: quel avenir?
Caprasse, Olivier ULg; Aydogdu, Roman ULg

in Revue Pratique des Sociétés Civiles et Commerciales (2005)

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See detailDissolved inorganic carbon dynamics and air-sea carbon dioxide fluxes during coccolithophore blooms in the northwest European continental margin (northern Bay of Biscay)
Suykens, Kim; Delille, Bruno ULg; Chou, Lei et al

in Global Biogeochemical Cycles (2010), 24

We report a data set of dissolved inorganic carbon (DIC) obtained during three cruises in the northern Bay of Biscay carried out in June 2006, May 2007, and May 2008. During these cruises, blooms of the ... [more ▼]

We report a data set of dissolved inorganic carbon (DIC) obtained during three cruises in the northern Bay of Biscay carried out in June 2006, May 2007, and May 2008. During these cruises, blooms of the coccolithophore Emiliania huxleyi occurred, as indicated by patches of high reflectance on remote sensing images, phytoplankton pigment signatures, and microscopic examinations. Total alkalinity showed a nonconservative behavior as a function of salinity due to the cumulative effect of net community calcification (NCC) on seawater carbonate chemistry during bloom development. The cumulative effect of NCC and net community production (NCP) on DIC and the partial pressure of CO2 (pCO(2)) were evaluated. The decrease of DIC (and increase of pCO(2)) due to NCC was overwhelmingly lower than the decrease of DIC (and decrease of pCO(2)) due to NCP (NCC: NCP << 1). During the cruises, the northern Bay of Biscay acted as a sink of atmospheric CO2 (on average similar to-9.7 mmol C m(-2) d(-1) for the three cruises). The overall effect of NCC in decreasing the CO2 sink during the cruises was low (on average similar to 12% of total air-sea CO2 flux). If this is a general feature in naturally occurring phytoplankton blooms in the North Atlantic Ocean (where blooms of coccolithophores are the most intense and recurrent), and in the global ocean, then the potential feedback on increasing atmospheric CO2 of the projected decrease of pelagic calcification due to thermodynamic CO2 "production" from calcification is probably minor compared to potential feedbacks related to changes of NCP. [less ▲]

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See detailDissolved inorganic carbon dynamics and air-sea carbon dioxide fluxes during coccolithophorid blooms in the Northeast European continental margin (northern Bay of Biscay)
Suykens, Kim; Delille, Bruno ULg; Chou, Lei et al

Poster (2010, May 03)

Balch et al. (2007) evaluated global pelagic contemporary calcification from remote sensing data (mainly associated to coccolithophores) to 1.6 ± 0.3 Pg PIC yr-1 (1 Pg = 1015 g; PIC = particulate ... [more ▼]

Balch et al. (2007) evaluated global pelagic contemporary calcification from remote sensing data (mainly associated to coccolithophores) to 1.6 ± 0.3 Pg PIC yr-1 (1 Pg = 1015 g; PIC = particulate inorganic carbon). This would imply that coccolithophores would be the most important pelagic calcifier in the oceans, since other estimates of contemporary global pelagic calcification range between 0.7 Pg PIC yr-1 based on accumulation rates and sediment trap data (Milliman et al. 1999), and 1.4 Pg PIC yr-1, based on the seasonal cycle of total alkalinity (TA) in the euphotic zone (Lee 2001). The development of coccolithophorid blooms affects the seawater carbonate chemistry, and air-sea CO2 fluxes, through the organic carbon pump and the carbonate counter-pump. The ratio between calcification (carbonate counter-pump), and organic carbon production (organic carbon pump), the C:P ratio, depends on the life cycle (bloom development), and growth conditions of coccolithophores. At the onset of the coccolithophorid bloom, when nutrients are available for growth, organic carbon production dominates over calcification (C:P << 1, the so-called organic phase). At the end of the bloom, in nutrient depleted conditions, and high irradiances (due to stronger stratification), organic carbon production decreases and calcification increases (C:P ≤ 1, the so-called inorganic phase). Several manipulative experiments to test the effect of ocean acidification on coccolithophores have shown that while calcification would decrease, the export of organic carbon would increase mainly through increasing transparent exopolymer particles (TEP) production. For a credible implementation in mathematical models of such feed-back mechanisms to allow the projection of a future evolution of carbon biogeochemistry under global change, it is required to understand present day biogeochemistry and ecology of naturally occurring pelagic calcifying communities. In particular, the overall effect of phytoplankton communities on the C:P ratio, and the net effect on carbonate chemistry, and related air-sea CO2 fluxes. [less ▲]

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See detailDissolved inorganic carbon dynamics and air-sea carbon dioxide fluxes during coccolithophorid blooms in the Northeast European continental margin (northern Bay of Biscay)
Suykens, Kim; Delille, Bruno ULg; Chou, Lei et al

Poster (2010, May 02)

We present a data-set of dissolved inorganic carbon (DIC) obtained during three cruises in the northern Bay of Biscay carried out in June 2006, May 2007, and May 2008. During these cruises, blooms of ... [more ▼]

We present a data-set of dissolved inorganic carbon (DIC) obtained during three cruises in the northern Bay of Biscay carried out in June 2006, May 2007, and May 2008. During these cruises, blooms of coccolithophores occurred, as indicated by patches of high reflectance on remote sensing images, phytoplankton pigment signatures, and microscopic examinations. Total alkalinity (TA) showed a non-conservative behaviour as a function of salinity due to the cumulated effect of net community calcification (NCC) during bloom development on seawater carbonate chemistry. The cumulated impact of NCC and net community production (NCP) on DIC and the partial pressure of CO2 (pCO2) were evaluated. The decrease of DIC (and increase of pCO2) due to NCC was overwhelmingly lower than the decrease of DIC (and decrease of pCO2) due to NCP (NCC:NCP « 1). During the cruises, the northern Bay of Biscay acted as a sink of atmospheric CO2 (on average -9.7 mmol C m-2 d-1 for the 3 cruises). The overall effect of NCC in decreasing the CO2 sink during the cruises was low (on average 12% of total air-sea CO2 flux). If this is a general feature in naturally occurring phytoplankton blooms in the northern North Atlantic Ocean (where coccolithophorid blooms are the most intense and recurrent), and in the global ocean, then the potential feed-back on increasing atmospheric CO2 of the projected decrease of pelagic calcification due to thermodynamic CO2 “production” from calcification is probably minor compared to feed-backs related to changes of NCP. [less ▲]

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See detailDissolved inorganic carbon dynamics in the Gulf of Biscay (June 2006)
Suykens, K.; Delille, Bruno ULg; Borges, Alberto ULg

Poster (2007, April)

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See detailDissolved Inorganic Carbon dynamics in the northern Bay of Biscay during a Coccolithophore bloom
Harlay, Jérôme ULg; van der Zee, Claar; Schiettecatte, Laure-Sophie et al

Poster (2005, May 02)

In the framework of the Belgian global change programme, we have developed a project devoted to the study of the inorganic carbon cycle in the Bay of Biscay where coccolithophore blooms occur frequently ... [more ▼]

In the framework of the Belgian global change programme, we have developed a project devoted to the study of the inorganic carbon cycle in the Bay of Biscay where coccolithophore blooms occur frequently. The study focuses on processes associated with the oceanic production and dissolution of calcium carbonate and related CO2 fluxes. Real time remote sensing allowed to localize the coccolithophore bloom that the R.V. Belgica visited in June 2004 during a multidisciplinary scientific cruise. We will present vertical profiles of pH, Talk, along with other parameters (salinity, temperature, chlorophyll a and phaeopigments) and 14C incorporation experiments. Inorganic carbon fluxes will be discussed in the photic zone, in correlation with the biological activity of phytoplankton (biological and carbonate pumps). [less ▲]

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