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Measurements of absolute total and partial cross sections for the electron ionization of tungsten hexafluoride (WF6)

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Bibliographic Details
Title: Measurements of absolute total and partial cross sections for the electron ionization of tungsten hexafluoride (WF6)
Authors: Basner, R.1 basner@inp-greifswald.de, Schmidt, M.1, Becker, K.2,3
Source: International Journal of Mass Spectrometry. Apr2004, Vol. 233 Issue 1-3, p25. 7p.
Subjects: Nuclear cross sections, Ionization (Atomic physics), Tungsten, Mass spectrometers
Abstract: We measured absolute partial cross sections for the formation of positive ions followed by electron impact on tungsten hexafluoride (WF6) from threshold to 900 eV using a time-of-flight mass spectrometer (TOF-MS). Dissociative ionization processes resulting in seven different singly charged ions (F+, W+, WFx+, x=1–5) and five doubly charged ions (W2+, WFx2+, x=1–4) were found to be the dominant ionization channels. The ion spectrum at all impact energies is dominated by WF5+ fragment ions. At 120 eV impact energy, the partial WF5+ ionization cross section has a maximum value of 3.92×10−16 cm2 that corresponds to 43% of the total ion yield. The cross section values of all the other singly charged fragment ions at 120 eV range between 0.39×10−16 and 0.73×10−16 cm2. The ionization cross sections of the doubly charged ions are more than one order of magnitude lower than the cross section of WF5+. Double ionization processes account for 21% of the total ion yield at 120 eV. The absolute total ionization cross section of WF6 was obtained as the sum of all measured partial ionization cross sections and is compared with available calculated cross sections. [Copyright &y& Elsevier]
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Description
Abstract:We measured absolute partial cross sections for the formation of positive ions followed by electron impact on tungsten hexafluoride (WF6) from threshold to 900 eV using a time-of-flight mass spectrometer (TOF-MS). Dissociative ionization processes resulting in seven different singly charged ions (F+, W+, WFx+, <F>x=1</F>–5) and five doubly charged ions (W2+, WFx2+, <F>x=1</F>–4) were found to be the dominant ionization channels. The ion spectrum at all impact energies is dominated by WF5+ fragment ions. At 120 eV impact energy, the partial WF5+ ionization cross section has a maximum value of <F>3.92×10−16</F> cm2 that corresponds to 43% of the total ion yield. The cross section values of all the other singly charged fragment ions at 120 eV range between <F>0.39×10−16</F> and <F>0.73×10−16</F> cm2. The ionization cross sections of the doubly charged ions are more than one order of magnitude lower than the cross section of WF5+. Double ionization processes account for 21% of the total ion yield at 120 eV. The absolute total ionization cross section of WF6 was obtained as the sum of all measured partial ionization cross sections and is compared with available calculated cross sections. [Copyright &y& Elsevier]
ISSN:13873806
DOI:10.1016/j.ijms.2003.10.014