Correlation between the x-ray induced and the electron-induced electron emission yields of insulators

Similarly to the constant loss model used for expressing the electron-induced secondary electron yield from solids, δ, a simple model is used for expressing the x-ray-induced electron emission yield, δX, from uncharged insulators. The two yields involve common mechanisms for the transport and the escape of the secondary electrons and are sensitive to the crystalline state, to the temperature and to the surface composition of the investigated insulator. For practical purposes, it is thus possible to estimate δX of the insulator of interest from the knowledge of δ and vice versa. In particular, these two yields may be related to each other by an expression of the form: δX/δ=μR hν/E0 (with μ linear absorption coefficient of the material of interest for incident photons of energy hν) when the range, R, of incident electrons (of energy E0) is far larger than the escape depth, s, of the secondary electrons. Deduced from some published δ(E0) curves, the illustrations concern the evolution in the photon energy range 0.5–10 keV for diamond and of CsI. Similar results on the temperature dependence of δX (between 77 K and 593 K) are also reported for NaCl. Conversely, the evolution of δ(E0) in the 0.5–5 keV energy range for CsI and for solid Xe is deduced from the data of photo electron emission δX experiments. The trends of δ in the 5-20 keV range are also established for various alkali halides while the application of the method to other materials such as metallic oxides, polymers or glasses is also suggested.

Перевод пока недоступен