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, delta, a simple model is used for expressing the x-ray-induced electron emission yield, delta (X), 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 delta (X) of the insulator of interest from the knowledge of delta and vice versa. In particular, these two yields may be related to each other by an expression of the form: delta (X)/delta = muR h nu /E-0 (with mu linear absorption coefficient of the material of interest for incident photons of energy h nu) when the range, R, of incident electrons (of energy E-0) is far larger than the escape depth, s, of the secondary electrons. Deduced from some published delta (E-0) 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 delta (X) (between 77 K and 593 K) are also reported for NaCl. Conversely, the evolution of delta (E-0) in the 0.5-5 keV energy range for CsI and for solid Xe is deduced from the data of photo electron emission delta (X) experiments. The trends of delta 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. (C) 2001 American Institute of Physics.