Transition energy plasma density

The calculated results for Sil et al. [174] agree well with those of Skupski [162] and Nguyen et al. [154], For hydrogen-like Al the transition energy vs plasma density [176] is plotted in Figure 13. 

Figure 13 Plot of relativistic and nonrelativistic transition energy (Is —> 2p) for Al12+ against the plasma electron density using Ion Sphere model. Reprinted with permission from [176] 2008, EDP Sciences...

The alkali metals, with only one free electron per atom, have lower plasmon energies than those of divalent free-electron metals such as Mg and A1 because the plasma frequency decreases with decreasing electron density. Thus, surface plasmon energies for alkali metals are in or near the visible, whereas they are in the far ultraviolet for Mg, Al, and Pb. Surface plasmon energies of the divalent metals Ag, Au, and Cu are shifted toward and into the visible because of interband transitions (see Fig. 12.9d) this is also the cause of the large values of c" for Au and Cu. 

The finite lifetime of each excited state is the reflection of a fundamental law of nature - tendency towards minimum total energy of a system. The quantum mechanical system tends to occupy the state in which its total energy would be minimal. However, the transition of an atom to the lowest (ground) state depends on many circumstances (first of all, on the sort of excited configuration, on the presence of external fields, on the character of the matter itself - density of gas, vapours or plasma, etc.). There are two main channels of decay of the excited states radiative and radiationless. In the first case the electronic transition from the higher to the lower state is connected with the radiation of one or several quanta of... 

Partially ionized gases are usually denoted as plasmas [4]. They contain molecules, radicals and atoms but also ions and free electrons and result from the coupling of energy with matter in the gaseous state. As has been previously stated for atoms, radicals, molecules and ions also present in the plasma can be in their ground states and in excited states and radiation can be emitted or absorbed when transitions from one state to another occur. The wavelength of the radiation can be obtained from Planck s law whereas the intensities of the discrete lines depend on the number densities of the species and the states involved. 

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