Metals secondary electron emission

Most of the publications dedicated to the interaction between the RGMAs and a solid surface refer to the rare gas - metal system. The secondary electron emission that occurs in the system allows one to judge of the mechanism that deactivates metastable atoms on a metal surface, as well as to evaluate the concentration of metastable atoms in the gaseous phase. 

In the forming of these polar bonds, electrons of the metals are withdrawn from the metal. The binding of electrons can be shown by the increase of the secondary electron emission (86,87), and conductivity measurements (88,89) and measurements of contact resistances (90,91) show that conduction electrons have been occupied by these bonds. The physical adsorption of a gas on a metallic surface, on the other hand, causes a slight increase of the conductivity of the metal (92,93). 

The plasma ionic liquid interface is interesting from both the fundamental and the practical point of view. From the more fundamental point of view, this interface allows direct reactions between free electrons from the gas phase without side reactions - once inert gases are used for the plasma generation. From the practical point of view, ionic liquids are vacuum-stable electrolytes that can favorably be used as solvents for compounds to be reduced or oxidised by plasmas. Plasma cathodic reduction may be used as a novel method for the generation of metal or semiconductor particles, if degradation reactions of the ionic liquid can be suppressed sufficiently. Plasma anodic oxidation with ionic liquids has yet to be explored. In this case the ionic liquid is cathodically polarized causing an enhanced plasma ion bombardment, that leads to secondary electron emission and fast decomposition of the ionic liquid. 

A nanofilm of plasma polymer (up to about 100 nm) has sufficient electrical conductance as evidenced by the fact that an LCVD-coated metal plate can be coated by the electrolytic deposition of paint (E coating), i.e., plasma polymer-coated metals can be used as the cathode of the electrolytic deposition of paint (see Chapter 31). Thus, the plasma polymer layer remains in the same electrical potential of the cathode (within a limited thickness) and the work function for the secondary electron emission does not increase significantly. When the thickness of plasma polymer deposition increases beyond a certain value, the coated metal becomes eventually insulated, and DC discharge cannot be sustained. DC cathodic polymerization is primarily aimed to lay down a nanofilm (10-100 nm) on the metal surface that is used as the cathode (see Chapter 13). 

Thus the early results obtained by the writer on secondary electron emission and LEED are characteristic of an approximately clean surface since the metals in use could be effectively cleaned by heat treatment as shown by LEED. 

The compounds formed often have higher secondary electron emission than metals, so that more of the energy transferred by the ions is used to produce and to accelerate secondary electrons. The increased secondary electron emission, in the case of constant-current power supplies, automatically decreases the cathode voltage for a fixed power setting. It is therefore -better to maintain a constant voltage. In this case the abrupt rate decrease becomes more smoothed out. 

Secondary Electron Emission from the Li.a and M2,3 Core Levels. In calculating the emission of the secondary electrons from the Is hydrogenlike core level, we succeeded in making analytical estimates and obtaining simple approximating expressions for the amplitude [Eq. (61)], the intensity of emission [Eq. (62)], and the angular correlation function [Eqs. (52), (53), (56)]. However in the study of the 3d metal SEFS it is essential to describe the emission of the secondary electrons from L2,3 and M2,3 core levels. Consider the ionization process of the L2,3 and M2,3 core level of the atom with the wave functions of the core level electron taken as... 

The characteristic feature of the 3d- and 4d-metal electronic structure is a strong localization of the wave functions of valence d-electrons on atoms. The end of the series of transition metals is characterized also by a large number of valence electrons on the atom. That is why the intensities of the second-order processes may be expected to be significant in the 3d- and 4d-metal secondary electron spectra. Considering the EFSs of the secondary electron spectrum—which are located above the low-energy CVV Auger lines (MW in 3d and NW in 4d metals), where the inverse radii of localization of the core-electron wave function are rather small—the values of the parameter natipC are expected to be sufficiently large then the intensity of the second-order process should be comparable to the intensity of the first-order processes in the atomic spectrum of secondary electron emission. 

Mesons, summary of properties, 11-1 to 55 Metal oxides, secondary electron emission, 12-120... 

Energetic ion bombardment of a surface causes the emission of secondary electrons. Metals generally have a secondary electron emission coefficient of less than 0.1 under ion bombardment while the secondary electron emission coefficients of oxide surfaces are higher. Secondary electron emission from electron bombardment is much higher than from ion bombardment. 

The most recent calculations, however, of the photoemission final state multiplet intensity for the 5 f initial state show also an intensity distribution different from the measured one. This may be partially corrected by accounting for the spectrometer transmission and the varying energy resolution of 0.12, 0.17, 0.17 and 1,3 eV for 21.2, 40.8, 48.4, and 1253.6 eV excitation. However, the UPS spectra are additionally distorted by a much stronger contribution of secondary electrons and the 5 f emission is superimposed upon the (6d7s) conduction electron density of states, background intensity of which was not considered in the calculated spectrum In the calculations, furthermore, in order to account for the excitation of electron-hole pairs, and in order to simulate instrumental resolution, the multiplet lines were broadened by a convolution with Doniach-Sunjic line shapes (for the first effect) and Gaussian profiles (for the second effect). The same parameters as in the case of the calculations for lanthanide metals were used for the asymmetry and the halfwidths ... 

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