Sur des transitions Raman faiblement permises dans l’hexafluorure de soufre : Spectroscopie de haute sensibilité de bandes harmoniques et induites

Abstract : Of all greenhouse gases (GHGs), carbon dioxide is definitely the most notorious to the wide public. Yet, there are GHGs present in much more tiny amounts in the Earth’s atmosphere, whose destructive power is substantial albeit less widely publicized. SF6 is a GHG considered as a dangerous pollutant of our atmosphere for that its global warming potential (GWP) amounts to about 24 000 times the GWP of CO2. Of anthropogenic origin, primarily owing to the industry of electrical insulators, the emissions of that gas are presently being increased at the alarming rate of 8% per year. These observations fully justify why sulfur hexafluoride currently tends to become a serious competitor of carbon dioxide and why its emissions are targeted in the Kyoto protocol. Here we present a study, both experimental and theoretical, of certain weakly-allowed Raman-scattering transitions related to gaseous SF6. These are either transitions in the isolated molecules or collision-induced transitions within pairs of molecules. Specifically, the overtones 2ν3 and 2ν5 of SF6 were studied, which both are Raman-active because of electrical or mechanical anharmonicity in the isolated molecule. This choice was prompted by the fact that ν3 and ν5 are the molecule’s most representative stretching and bending vibrations, respectively. It follows an experimental study of the collision-induced SF6−SF6 transition at the position of the ν3 vibration, as well as other transitions related to the isolated molecule. The high-sensitivity Raman equipment we have used and the stiff protocol we have followed regarding detection, acquisition, processing and analysis of spectra are part of a long experience and knowhow within a research group recognized for its capacity to capture and analyze extremely weak light signals.
Document type :
Theses
Complete list of metadatas

https://tel.archives-ouvertes.fr/tel-01112199
Contributor : Anne-Marie Plé <>
Submitted on : Monday, February 2, 2015 - 4:26:28 PM
Last modification on : Friday, May 10, 2019 - 1:02:02 PM
Long-term archiving on : Saturday, September 12, 2015 - 7:35:28 AM

Identifiers

  • HAL Id : tel-01112199, version 1

Citation

David Kremer. Sur des transitions Raman faiblement permises dans l’hexafluorure de soufre : Spectroscopie de haute sensibilité de bandes harmoniques et induites. Physique [physics]. Université d'Angers, 2014. Français. ⟨tel-01112199⟩

Share

Metrics

Record views

290

Files downloads

115