ionization cross section

ionization cross section

[‚ī·ə·nə′zā·shən ′krȯs ¦sek·shən]
(physics)
The cross section for a particle or photon to undergo a collision with an atom, thus removing or adding one or more electrons to the atom.
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References in periodicals archive ?
To proceed anyway, note that C includes intrinsic and extrinsic effects: the partial ionization cross section (i.e., intrinsic ion yield) [2], [[sigma].sub.A]x, and the responsivity of the instrument, [beta].
PICS values, which are intrinsic molecular properties, are estimated by combining an ab initio total ionization cross section (TICS) with empirical ion-branching fractions, as described in detail elsewhere [4] and summarized below.
[11] Kim Y-K, Irikura KK, Rudd ME, Zucker DS, Zucker MA, Coursey JS, Olsen KJ, Wiersma GG (2001) Electron-Impact Ionization Cross Section Database.
To calculate the intensity of x-ray emission in electron beam microanalysis requires a knowledge of the energy distribution of the electrons in the solid, the energy variation of the ionization cross section of the relevant subshell, the fraction of ionizations events producing x rays of interest and the absorption coefficient of the x rays on the path to the detector.
The intensity of x rays emitted when an electron beam strikes a sample depends on the energy distribution of the electrons in the solid, the energy variation of the ionization cross section of the relevant subshell, the fraction of ionization events that give x rays in the line of interest and the absorption coefficient of the x rays on the path to the detector.
where I(E, r) is the distribution of electrons in the specimen as a function of energy E and position r, [[sigma].sub.x](E) is the ionization cross section for the relevant subshell, [f.sub.x] is the fraction of ionization events producing x rays in the line of interest and [[sigma].sub.x] is the absorption coefficient for the x rays on their path to the detector at position [r.sub.0].
The direct measurement of only the doubly charged ions-processes (5), (7), and (8)-tends to produce small cross sections compared to the total ionization cross section because of the high probability for the rapid break-up of the doubly charged ions as shown in Ref.
The Binary-Encounter-Bethe (BEB) model for electron-impact total ionization cross sections has been applied to [CH.sup.+.sub.2], [CH.sup.+.sub.3], [CH.sup.+.sub.4], [C.sub.2][H.sup.+.sub.2], [C.sub.2][H.sup.+.sub.4], [C.sub.2][H.sup.+.sub.6], and [H.sub.3][O.sup.+].
A time-dependent close-coupling method is used to calculate antiproton-impact single ionization, ionization with excitation, and double ionization cross sections for H$_2$ between 5.0 keV and 1.5 MeV.
(N.B.: the 70 eV EI ionization cross sections increase linearly with MW.) As a result, the RF's (and also MDL's in mass units) will be essentially constant, irrespective of MW assuming quantitative recovery.
This scaling is similar to a scaling for ionization cross sections used earlier by Burgess [3], who shifted the incident energy T by B + U, where U is the kinetic energy of the target electron.
This scaling is similar to a scaling for ionization cross sections used earlier by Burgess (2), who shifted the incident energy T by B+U, where U is the kinetic energy of the target electron.