Stopping power

Ema data can be quantitated to provide elemental concentrations, but several corrections are necessary to account for matrix effects adequately. One weU-known method for matrix correction is the 2af method (7,31). This approach is based on calculated corrections for major matrix-dependent effects which alter the intensity of x-rays observed at a particular energy after being emitted from the corresponding atoms. The 2af method corrects for differences between elements in electron stopping power and backscattering (the correction), self-absorption of x-rays by the matrix (the a correction), and the excitation of x-rays from one element by x-rays emitted from a different element, or in other words, secondary fluorescence (the f correction). 

J. F. Ziegler,. P. Biersack, and U. Littmark. Stopping Powers and Ranges in All Elements. Pergamon Press, New York, 1977, vol.1-6. 

A depth scale can be obtained from the energy of recoiled ions. If ions recoiled from a depth x are lower in energy by AE compared with ions recoiled from the surface, a simple relationship between AE and x can be found for thin layers, when constant stopping power is assumed ... 

The depth resolution in resonance NRA close to the surface is mainly determined by the stopping power of the projectiles in the target. For deeper layers, there are different contributions ... 

P. Duncamb, S. j. B. Reed in K. F. J. Heinrich (ed.) The Calculation of Stopping Power and Backscattcr Effects in Electron Probe Microanalysis, NBS Special Publ. 298, Washington, 1968. 

Our particular interest lies in the calculation of the linear energy deposition, or stopping power, of swift ions in materials, 5o(v). In the first Born approximation, and for a fully stripped projectile, this quantity can be written [2-4]... 

Here Z is the charge of the projectile with velocity v. In order to calculate stopping powers for atomic and molecular targets with reliability, however, one must choose a one-electron basis set appropriate for calculation of the generalized oscillator strength distribution (GOSD). The development of reasonable criteria for the choice of a reliable basis for such calculations is the concern of this paper. 

Figure 5 Stopping power for protons on He calculated with the standard basis (basis A), with two consistent bases (B and C), and in the Bethe approximation using the kinetic theory [17, 18],...

Figure 1. Electronic and nuclear energy loss function of (a) Au implanted in Si02 and (b) He implanted in Si02. The fraction of the electronic or nuclear 5 stopping power with respect to the total (S tot = S + for Au (c) and He (d). (Reprinted from Ref [1], 2005, with permission from Italian Physical Society.)...

Nuclear component of the stopping power SPR Surface plasma resonance... 

Leaching of nuclides implanted into adjacent minerals has been suggested for the supply of Rn into the vadose zone. Where there are intermittent undersaturated conditions, i.e., in soils or rocks where the water table lowers seasonally, the low stopping power of air allows atoms ejected from minerals to be implanted across pore spaces. These atoms will then be available for leaching... 

Stopping Power—The average rate of energy loss of a charged particle per unit thickness of a material or per unit mass of material traversed. 

The stopping power of a material is defined as the energy loss per distance travelled in the material, dE/dz, and the Bragg rule may be expressed more generally, if the stopping cross-sections for each element are known ... 

Straggling thus limits the depth and mass resolution for features buried within the target material. The depth resolution, Az depends on the stopping power, dE/dz, the detector resolution, AEdet and the beam energy spread, AEbeam of the incident particles ... 

Fs is the stopping power factor. Electron penetration is a function not only of the incident electron energy (which is constant for a given analysis) but also on the stopping power of the sample, which depends somewhat on atomic number. Reed (1993) derives equations for the generated characteristic X-ray intensity, leading to expressions for Fs. 

The electronic stopping power of the 2 MeV Ne+ ions in the palladium acetate films is much larger than that of 2 MeV He ions. The most obvious difference between the effects of the two ions is in the appearance of the films at the high dose limit. A 0.90 nm thick palladium acetate film exposed to 2 MeV Ne+ ion irradiation until no further spectroscopic changes occur looks black, compared with the metallic silvery films produced in the He ion irradiation. However... 

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