PMC

Illustration of dynamic mechanisms in InSb and InAs band structure: impact ionization in the Γ valley (1), impact ionization in the L valley (2), Γ-L intervalley scattering (3), and X-L intervalley scattering (4).

The impact ionization coefficients of electrons.

Plots of the Bethe parameters b_i and c_i (i= K, L, or M) as a function of Z from fits with in the high-and low-energy regions of the Fano plots in to for K-shell ionization (blue squares), L-shell ionization (red circles), and M-shell ionization (green diamonds). The left panels show plots of b_i while the right panels show plots of c_i. The top panels show the Bethe parameters from the fits in the high-energy regions of the Fano plots ( to for K-shell ionization, and for L-shell ionization, and for M-shell ionization, as listed in , , and ). The bottom panels show the Bethe parameters from the fits in the low-energy regions of the Fano plots ( to 10 for K-shell ionization, and for L-shell ionization, and for M-shell ionization, as listed in , , and ). Error bars, corresponding to one-standard-deviation uncertainties of the Bethe parameters obtained from the fits with the low-energy Fano plots, are smaller than the size of the symbols. Values of b_L3 and c_L3 for Xe are also included in each panel with values of b_L and c_L, respectively.

Fano plot of the electron impact ionization cross section of lithium. —— total ionization cross section computed in the distorted wave exchange approximation (present); –·–·– 2s ionization cross section, distorted wave exchange approximation (present); ——— Plane wave Born, Ref. []; ---- Plane wave Born, Ref. ; ○ Bethe theory, Ref. ; ● Crossed-beam experiment, Ref. []; ▲ Crossed-beam experiment, Ref. ; Crossed-beam experiment, Ref. []