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Collisional ionization electron attachment

Compton studied the formation of both positive and negative ions by electron ionization and electron attachment in UFs (Compton, 1977). The cross section for the electron ionization of UFe from the threshold electron energy, 14 eV, to 1 keV exhibited a maximum of 18 at 160 eV. Reactions of UFs with electrons and alkali metal atoms to produce uranium fluoride anions confirmed the high electron affinity of UFe and demonstrated that D(UF5 —F) and D(UF5-F ) are similar, to within 1 eV, but are both 2 eV greater than D(UF5-F). That the U—F bonds are stronger in UFe" than in UFs reflects the large electron affinity of UFe. Streit and Newton reported that exothermic electron transfer from halide anions and SFe to UFe occurs close to the collisional rate (Streit and Newton, 1980), a result that renders particularly intriguing the nonoccurrence of thermoneutral Eq. 8 due to an unanticipated barrier. [Pg.37]

The data for liquid xenon were obtained in a coaxial test cell consisting of a thin wire as anode (2.0 to 5.0 pm diameter) and an outer cylinder (8 mm diameter) as cathode. For the production of the initial electrons, a radioactive ° Hg source was used. It emits quanta of 85 and 279 keV energy. When a 279-keV quant interacts with a xenon atom it produces an energetic photoelectron which dissipates its energy in approximately 12,500 ionization events. These ionization events are distributed around the point of interaction in a radius of 240 pm. It can be assumed that each photoelectron produces a sphere filled with electrons (and positive ions) at some distance r from the wire. Neglecting for the moment recombination and attachment, these electrons drift toward the anode wire and at some distance their mean energy is sufficient for collisional ionization. At that point they drift with the saturation velocity of 3 x lO cm/s. The number of electrons formed up to a distance r is obtained from integration of Equation 1 as... [Pg.286]


See other pages where Collisional ionization electron attachment is mentioned: [Pg.35]    [Pg.111]    [Pg.19]    [Pg.5]    [Pg.121]    [Pg.233]    [Pg.242]    [Pg.14]    [Pg.128]    [Pg.451]    [Pg.349]    [Pg.456]    [Pg.458]    [Pg.122]   


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