A carregar...
Publicação
Negative Ion Formation in Potassium-Purine Molecules collisions
| Nome: | Descrição: | Tamanho: | Formato: | |
|---|---|---|---|---|
| 10.76 MB | Adobe PDF |
Autores
Orientador(es)
Resumo(s)
The research described in this thesis focuses on the study of electron transfer mechanisms
in purine molecules and derivatives (adenine, 9-methyl adenine, 6-dimethyl adenine
and 2-D adenine), in potassium-molecule collisions. The studies were performed
in a crossed beam experiment, comprising a neutral potassium beam and a biomolecular
effusive beam with a time-of-flight mass spectrometer and a recently implemented hemispherical
analyser, yielding an experimental arrangement capable of providing relevant
information of the collision dynamics. From this comprehensive investigation, we report
for the first time, collision induced site and bond selective breaking in purine molecules
by alkali collisions. The influence of the K+ ion in the vicinity of the temporary molecular
anion was also investigated, indicating to partially suppress auto-detachment resulting
in new or enhanced dissociation pathways.
Concerning the energy loss set-up, we present in the 0 to 15 eV energy range novel
K+ profiles in the forward direction ( 0 ) from fast potassium collisions with nitromethane
and tetrachloromethane where new features are unravelled, and reported for
the first time as far as akali collisions are concerned. Due to the current configuration, it
restricts the use of this technique exclusively to samples with high vapour pressure. The
potassium beam energy resolution was determined to be 0.6 eV in the laboratory frame.
Descrição
Palavras-chave
Electron transfer ion-pair formation time-of-flight mass spectrometry atommolecules collisions DNA nucleobases energy loss spectroscopy