{"id":{"repo_id":"liege","oai_identifier":"oai:orbi.ulg.ac.be:2268/38284"},"canonical_url":"https://search.dev.ndltd.org/etd/liege/oai:orbi.ulg.ac.be:2268/38284","repository":{"repo_id":"liege","name":"Université de Liège","base_url":"https://orbi.uliege.be/oai/request"},"display":{"title":"Etude par Spectrométrie de Masse de la formation d'Ions Négatifs par Attachement Electronique Dissociatif et par le processus de Paire d'Ions.","abstract":"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.","abstract_html":"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.","abstract_has_math":false,"creators":["Locht, Robert"],"institution":"ULiège - Université de Liège","degree_name":null,"degree_level":null,"degree_discipline":null,"degree_department":null,"school":null,"contributors":["D'Or, L.","Momigny, J.","Laboratoire des Etats Ionisés (afterwards: Laboratory for Molecular Dynamics)"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":1971,"date_issued":"1971-04-23","date_published":"1971-04-23","updated_at":"2026-07-24T02:49:27Z","subjects":["Electroionization","Mass spectrometry","Negative Ions","Dissociative Electron Attachment","Ion Pair Process","Deconvolution","Diatomic Molecules (H2, O2, CO, NO)","Triatomic Molecules (CO2, CS2)","Polyatomic Molecules (CH4, C2H2, C2H4, C2H3F, C2H3Cl)","Physical, chemical, mathematical & earth Sciences","Chemistry","Physique, chimie, mathématiques & sciences de la terre","Chimie"],"languages":["fr"],"rights":["open access","info:eu-repo/semantics/openAccess"],"rights_urls":["http://purl.org/coar/access_right/c_abf2"],"identifier_entries":[{"key":"dc:identifier","label":"Identifier","values":["info:hdl:2268/38284"],"render_values":[{"text":"info:hdl:2268/38284","href":null,"code":true}]}]},"links":{"outbound_url":"https://orbi.uliege.be/handle/2268/38284","outbound_label":"Repository record","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["D'Or, L.","Momigny, J.","Laboratoire des Etats Ionisés (afterwards: Laboratory for Molecular Dynamics)"]},{"key":"dc:creator","label":"Author","values":["Locht, Robert"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["1971-04-23"]},{"key":"dc:publisher","label":"Institution","values":["ULiège - Université de Liège"]},{"key":"dc:type","label":"Dc Type","values":["doctoral thesis","http://purl.org/coar/resource_type/c_db06","info:eu-repo/semantics/doctoralThesis"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Electroionization","Mass spectrometry","Negative Ions","Dissociative Electron Attachment","Ion Pair Process","Deconvolution","Diatomic Molecules (H2, O2, CO, NO)","Triatomic Molecules (CO2, CS2)","Polyatomic Molecules (CH4, C2H2, C2H4, C2H3F, C2H3Cl)","Physical, chemical, mathematical & earth Sciences","Chemistry","Physique, chimie, mathématiques & sciences de la terre","Chimie"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["fr"]},{"key":"dc:rights","label":"Dc Rights","values":["open access","http://purl.org/coar/access_right/c_abf2","info:eu-repo/semantics/openAccess"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["https://orbi.uliege.be/handle/2268/38284","info:hdl:2268/38284","https://orbi.uliege.be/bitstream/2268/38284/1/LOCHT_1971_PhDThesis.pdf"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["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."]},{"key":"dc:format","label":"Dc Format","values":["229"]},{"key":"dc:title","label":"Title","values":["Etude par Spectrométrie de Masse de la formation d'Ions Négatifs par Attachement Electronique Dissociatif et par le processus de Paire d'Ions.","Mass Spectrometric Study of the formation of Negative Ions by Dissociative Electron Attachment and by Ion-Pair process."]}]}],"canonical_facts":{"dc:contributor":["D'Or, L.","Momigny, J.","Laboratoire des Etats Ionisés (afterwards: Laboratory for Molecular Dynamics)"],"dc:creator":["Locht, Robert"],"dc:date":["1971-04-23"],"dc:description":["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."],"dc:format":["229"],"dc:identifier":["https://orbi.uliege.be/handle/2268/38284","info:hdl:2268/38284","https://orbi.uliege.be/bitstream/2268/38284/1/LOCHT_1971_PhDThesis.pdf"],"dc:language":["fr"],"dc:publisher":["ULiège - Université de Liège"],"dc:rights":["open access","http://purl.org/coar/access_right/c_abf2","info:eu-repo/semantics/openAccess"],"dc:subject":["Electroionization","Mass spectrometry","Negative Ions","Dissociative Electron Attachment","Ion Pair Process","Deconvolution","Diatomic Molecules (H2, O2, CO, NO)","Triatomic Molecules (CO2, CS2)","Polyatomic Molecules (CH4, C2H2, C2H4, C2H3F, C2H3Cl)","Physical, chemical, mathematical & earth Sciences","Chemistry","Physique, chimie, mathématiques & sciences de la terre","Chimie"],"dc:title":["Etude par Spectrométrie de Masse de la formation d'Ions Négatifs par Attachement Electronique Dissociatif et par le processus de Paire d'Ions.","Mass Spectrometric Study of the formation of Negative Ions by Dissociative Electron Attachment and by Ion-Pair process."],"dc:type":["doctoral thesis","http://purl.org/coar/resource_type/c_db06","info:eu-repo/semantics/doctoralThesis"]},"updated_at":"2026-07-24T02:49:27Z"}