Electron-Induced Synthesis of Ozone in a Dioxygen Matrix
1997; American Physical Society; Volume: 79; Issue: 6 Linguagem: Inglês
10.1103/physrevlett.79.1146
ISSN1092-0145
AutoresS. Lacombe, Franz Cemič, K. Jacobi, Mohamed Nejib Hedhili, Y. Le Coat, R. Azria, M. Tronc,
Tópico(s)Electronic and Structural Properties of Oxides
ResumoOzone (${\mathrm{O}}_{3}$) was synthesized in the condensed phase induced by electron bombardment of multilayer films of molecular oxygen condensed at temperatures below 30 K on metal surfaces. ${\mathrm{O}}_{3}$ formation was demonstrated by the observation of the asymmetric stretching ( ${\ensuremath{\nu}}_{3}$) and bending ( ${\ensuremath{\nu}}_{2}$) normal modes of vibration in a high-resolution electron energy-loss spectroscopy experiment, and by characteristic changes in electron-stimulated desorption of ${\mathrm{O}}^{\ensuremath{-}}$. The threshold electron energy for the ${\mathrm{O}}_{3}$ formation is found at $3.5\ifmmode\pm\else\textpm\fi{}0.2\mathrm{eV}$. It corresponds to the formation of O${(}^{3}$P) associated with ${\mathrm{O}}^{\ensuremath{-}}(^{2}P)$ by dissociative electron attachment at condensed ${\mathrm{O}}_{2}$, followed by the third body reaction $\mathrm{O}+{\mathrm{O}}_{2}+{\mathrm{O}}_{2}\ensuremath{\rightarrow}{\mathrm{O}}_{3}+{\mathrm{O}}_{2}$. Above 5.1 eV bombarding energy, dissociative excitation of the ${\mathrm{O}}_{2}^{*}$ ( ${c}^{1}{\ensuremath{\Sigma}}_{u}^{\ensuremath{-}}{,C}^{3}{\ensuremath{\Delta}}_{u}{,A}^{3}{\ensuremath{\Sigma}}_{u}^{+}{,B}^{3}{\ensuremath{\Sigma}}_{u}^{\ensuremath{-}}$) states is the main source of atomic oxygen O${(}^{3}$P) or O${(}^{1}$D) involved in the ${\mathrm{O}}_{3}$ synthesis.
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