Critical excitation energy

Equation (1) demonstrates that the analyst must choose a beam energy that exceeds the critical excitation energy for the species to be analyzed. In general, a value of f/> 2 is required to achieve adequate efficiency in the production of X rays. 

Reed (1966) produced the nomogram of Figure 5.8 for spatial resolution (d) as a function of density, incident electron energy and critical excitation energy. In the diagram, the case for iron (EC = 1A keY, p = 7) gives an estimated value of d at 20 keY of 0.8 pm, so the resolution for quantitative analysis is approximately 2.4 pm. 

Figure 5.8. Nomogram for spatial resolution (d), in pm, as a function of density (p), in g/cm3, incident electron energy (E0) and critical excitation energy (Ec), both in keV. The case for 20 keV electrons in...

Also, the friction sensy which is stated as 12 kp pistil load ] 28) M.Ya. VasiTev, Dependence of the Critical Excitation Energy of Explosion by Impact on the Density of Explosives , Deposited Doc, VINITI, 1247-76 (1975) CA 88, 76093... 

Critical Excitation Energies of the Exciting Radiation/Particles... 

The excitation by X-ray sources requires the knowledge about the values of critical excitation energies of different som ces to enable the excitation of inner-shell electrons of various elements present/expected to be present in the sample. Two basic processes i.e., the attenuation and the scattering of X-rays are involved when the intensity is reduced to after the photon beam of intensity lo passes through the material of thickness x. The reduced intensity is given by Lambert law = Iq exp(— o ), where p is called the linear atten-... 

The sharp discontinuities in the absorption curve are related to the critical excitation energies (and their corresponding wavelengths) of the element for the K-shell/ Lj, Ln, and Lni subshells of the L-shell/ Mj, Mu, Mm, Mjv, and Mv subshells of the M-shell, etc. The K- and L-shell absorption edges for a few elements given in wavelength (A) by Bearden (1967), converted in keV,... 

After the authors of Ref. 47, the motion of charged solitons in dimerized chains requires a relatively low excitation energy, and it could take place according to the following scenario. At low electric field, this motion is hindered by the three-dimensional interactions between molecular chains. The current is then due to a few defects more or less free from these interactions. As the field is increased, more and more charged solitons are driven to motion and by a cooperative effect of these mobile solitons, a critical field th is finally attained at which value the three-dimensional order is lost. The solitons are then able to move in one chain almost independent of the others, and this new degree of freedom is believed to... 

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