{"id":{"repo_id":"heid-diss","oai_identifier":"oai:archiv.ub.uni-heidelberg.de:5874"},"canonical_url":"https://search.dev.ndltd.org/etd/heid-diss/oai:archiv.ub.uni-heidelberg.de:5874","repository":{"repo_id":"heid-diss","name":"Universität Heidelberg","base_url":"http://archiv.ub.uni-heidelberg.de/volltextserver/cgi/oai2"},"display":{"title":"Investigation of the Oxygen Isotope Exchange Between Carbon Dioxide and O3 via O(1D)","abstract":"Carbon dioxide in the middle atmosphere shows an increasing enrichment in the heavy oxygen isotopes with altitude which preferential enrichment for 17O according to d17O =1.7 d18O. This is contrary to tropospheric CO2 where d17O ~ 0.5d18O. These isotope enrichments are transferred from O3 into CO2, but details of the mechanism are not understood yet. A systematic study was carried out using O2 and CO2 gases of different isotopic composition. Results show the existence of a photochemical isotope equilibrium between O2 and CO2, which is independent of the initial isotopic composition and shows equal enrichments for 17O and 18O. Additional experiments were conducted to investigate the effect of temperature, pressure and O2/CO2 ratio. Data revealed that the magnitude of enrichment at photochemical equilibrium depends on pressure and on O2/CO2 ratios with a decrease in enrichment at higher pressures. Also, the enrichment in CO2 showed a positive temperature dependence. The measurement of asymmetric O3 in one experiment yields additional insight into the isotope exchange mechanism and shows the absence of anomalous fractionation steps in the CO3* intermediate. The experimental data were modeled with the chemical kinetics software Facsimile. In addition, a large set of new measurements of the isotopic composition of stratospheric CO2 are presented, extending the earlier data down to the tropopause.","abstract_html":"Carbon dioxide in the middle atmosphere shows an increasing enrichment in the heavy oxygen isotopes with altitude which preferential enrichment for 17O according to d17O =1.7 d18O. This is contrary to tropospheric CO2 where d17O ~ 0.5d18O. These isotope enrichments are transferred from O3 into CO2, but details of the mechanism are not understood yet. A systematic study was carried out using O2 and CO2 gases of different isotopic composition. Results show the existence of a photochemical isotope equilibrium between O2 and CO2, which is independent of the initial isotopic composition and shows equal enrichments for 17O and 18O. Additional experiments were conducted to investigate the effect of temperature, pressure and O2/CO2 ratio. Data revealed that the magnitude of enrichment at photochemical equilibrium depends on pressure and on O2/CO2 ratios with a decrease in enrichment at higher pressures. Also, the enrichment in CO2 showed a positive temperature dependence. The measurement of asymmetric O3 in one experiment yields additional insight into the isotope exchange mechanism and shows the absence of anomalous fractionation steps in the CO3* intermediate. The experimental data were modeled with the chemical kinetics software Facsimile. In addition, a large set of new measurements of the isotopic composition of stratospheric CO2 are presented, extending the earlier data down to the tropopause.","abstract_has_math":false,"creators":["Shaheen, Robina"],"institution":"Universität Heidelberg","degree_name":null,"degree_level":"thesis.doctoral","degree_discipline":null,"degree_department":null,"school":null,"contributors":["Dr. Wolfgang Krätschmer"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2005,"date_issued":"2005-10-28","date_published":"2005-10-28","updated_at":"2026-07-24T02:30:12Z","subjects":[],"languages":[],"rights":[],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"http://www.ub.uni-heidelberg.de/archiv/5874","outbound_label":"Repository record","outbound_source":"source_url"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Dr. Wolfgang Krätschmer"]},{"key":"dc:creator","label":"Author","values":["Shaheen, Robina"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:publisher","label":"Institution","values":["Universitätsbibliothek Heidelberg"]},{"key":"dc:type","label":"Dc Type","values":["doctoralThesis"]},{"key":"thesis:degree_level","label":"Degree Level","values":["thesis.doctoral"]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["Universität Heidelberg"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["Carbon dioxide in the middle atmosphere shows an increasing enrichment in the heavy oxygen isotopes with altitude which preferential enrichment for 17O according to d17O =1.7 d18O. This is contrary to tropospheric CO2 where d17O ~ 0.5d18O. These isotope enrichments are transferred from O3 into CO2, but details of the mechanism are not understood yet. A systematic study was carried out using O2 and CO2 gases of different isotopic composition. Results show the existence of a photochemical isotope equilibrium between O2 and CO2, which is independent of the initial isotopic composition and shows equal enrichments for 17O and 18O. Additional experiments were conducted to investigate the effect of temperature, pressure and O2/CO2 ratio. Data revealed that the magnitude of enrichment at photochemical equilibrium depends on pressure and on O2/CO2 ratios with a decrease in enrichment at higher pressures. Also, the enrichment in CO2 showed a positive temperature dependence. The measurement of asymmetric O3 in one experiment yields additional insight into the isotope exchange mechanism and shows the absence of anomalous fractionation steps in the CO3* intermediate. The experimental data were modeled with the chemical kinetics software Facsimile. In addition, a large set of new measurements of the isotopic composition of stratospheric CO2 are presented, extending the earlier data down to the tropopause.","In der mittleren Atmosphäre zeigt Kohlendioxid eine Anreicherung in den schweren Sauerstoffisotopen, die mit der Höhe zunimmt wobei 17O bevorzugt in CO2 zu finden ist. Es ergibt sich der ungewöhnliche Zusammenhang d17O =1.7d18O. Für troposphärisches CO2 dagegen gilt: d17O ~ 0.5 d18O. Diese Isotopenanreicherungen werden von O3 in CO2 übertragen, aber die Details des Isotopentransfers sind noch nicht verstanden. In dieser Arbeit wurde eine systematische Studie unter Verwendung von O2 und CO2 unterschiedlicher Isotopenzusammensetzung durchgeführt. Die Ergebnisse zeigen ein photochemisches Isotopengleichgewicht zwischen O2 und CO2, das unabhängig von der anfänglichen Isotopenzusammensetzung ist und ähnliche Anreicherungen für 17O und 18O aufweist. Weitere Experimente zum Einfluss von Temperatur, Druck und Mischungsverhältnis wurden durchgeführt. Die Anreicherungen im photochemischen Gleichgewicht sind abhängig vom Druck und dem O2/CO2 Verhältnis und nehmen mit zunehmendem Druck ab. Sie zeigen außerdem eine positive Temperaturabhängigkeit. Die Messung von asymmetrischem Ozon in einem Experiment liefert zusätzliche Einsichten in den Isotopenaustauschprozess und zeigt, dass keine anomalen Isotopeneffekte im intermediären CO3* Komplex auftreten. Die experimentellen Daten wurden mit der Software Facsimile modelliert. Zusätzlich werden neue Isotopenmessungen von stratosphärischem CO2 vorgestellt, die die vorhandenen Messungen bis zur Tropopause vervollständigen."]},{"key":"dc:format.medium","label":"Dc Format Medium","values":["application/pdf"]},{"key":"dc:title","label":"Title","values":["Investigation of the Oxygen Isotope Exchange Between Carbon Dioxide and O3 via O(1D)","Untersuchung zum Sauerstoffisotopenaustausch zwischen Kohlendioxid und Ozon via O(1D)"]}]}],"canonical_facts":{"dc:contributor":["Dr. Wolfgang Krätschmer"],"dc:creator":["Shaheen, Robina"],"dc:description.abstract":["Carbon dioxide in the middle atmosphere shows an increasing enrichment in the heavy oxygen isotopes with altitude which preferential enrichment for 17O according to d17O =1.7 d18O. This is contrary to tropospheric CO2 where d17O ~ 0.5d18O. These isotope enrichments are transferred from O3 into CO2, but details of the mechanism are not understood yet. A systematic study was carried out using O2 and CO2 gases of different isotopic composition. Results show the existence of a photochemical isotope equilibrium between O2 and CO2, which is independent of the initial isotopic composition and shows equal enrichments for 17O and 18O. Additional experiments were conducted to investigate the effect of temperature, pressure and O2/CO2 ratio. Data revealed that the magnitude of enrichment at photochemical equilibrium depends on pressure and on O2/CO2 ratios with a decrease in enrichment at higher pressures. Also, the enrichment in CO2 showed a positive temperature dependence. The measurement of asymmetric O3 in one experiment yields additional insight into the isotope exchange mechanism and shows the absence of anomalous fractionation steps in the CO3* intermediate. The experimental data were modeled with the chemical kinetics software Facsimile. In addition, a large set of new measurements of the isotopic composition of stratospheric CO2 are presented, extending the earlier data down to the tropopause.","In der mittleren Atmosphäre zeigt Kohlendioxid eine Anreicherung in den schweren Sauerstoffisotopen, die mit der Höhe zunimmt wobei 17O bevorzugt in CO2 zu finden ist. Es ergibt sich der ungewöhnliche Zusammenhang d17O =1.7d18O. Für troposphärisches CO2 dagegen gilt: d17O ~ 0.5 d18O. Diese Isotopenanreicherungen werden von O3 in CO2 übertragen, aber die Details des Isotopentransfers sind noch nicht verstanden. In dieser Arbeit wurde eine systematische Studie unter Verwendung von O2 und CO2 unterschiedlicher Isotopenzusammensetzung durchgeführt. Die Ergebnisse zeigen ein photochemisches Isotopengleichgewicht zwischen O2 und CO2, das unabhängig von der anfänglichen Isotopenzusammensetzung ist und ähnliche Anreicherungen für 17O und 18O aufweist. Weitere Experimente zum Einfluss von Temperatur, Druck und Mischungsverhältnis wurden durchgeführt. Die Anreicherungen im photochemischen Gleichgewicht sind abhängig vom Druck und dem O2/CO2 Verhältnis und nehmen mit zunehmendem Druck ab. Sie zeigen außerdem eine positive Temperaturabhängigkeit. Die Messung von asymmetrischem Ozon in einem Experiment liefert zusätzliche Einsichten in den Isotopenaustauschprozess und zeigt, dass keine anomalen Isotopeneffekte im intermediären CO3* Komplex auftreten. Die experimentellen Daten wurden mit der Software Facsimile modelliert. Zusätzlich werden neue Isotopenmessungen von stratosphärischem CO2 vorgestellt, die die vorhandenen Messungen bis zur Tropopause vervollständigen."],"dc:format.medium":["application/pdf"],"dc:publisher":["Universitätsbibliothek Heidelberg"],"dc:title":["Investigation of the Oxygen Isotope Exchange Between Carbon Dioxide and O3 via O(1D)","Untersuchung zum Sauerstoffisotopenaustausch zwischen Kohlendioxid und Ozon via O(1D)"],"dc:type":["doctoralThesis"],"thesis:degree_level":["thesis.doctoral"],"thesis:institution_name":["Universität Heidelberg"]},"updated_at":"2026-07-24T02:30:12Z"}