Charge neutralization Collision

In charge exchange collisions the cross-section depends upon the energetics of the reaction. To compute the energy defect, the initial and final states of the colliding particles must be specified. This can be done easily for the bombarded neutral molecule, which usually can be assumed to be in the ground state before the collision, but not for the incident ion which is often in one of its metastable states. 

If a macroscopic chunk of quark matter is created in heavy ion collisions or exists inside the compact stars, it must be in color singlet. So in the following discussions, color charge neutrality condition is always satisfied. 

Figure 16.15—Electron ionisation (El). The collision of an electron with a sample molecule m produces ionisation that leads to formation of a parent ion and fragment ions. Ions that result from the reaction m/ and raj are also called secondary or daughter ions. Since they carry no charge, neutral fragments produced during decomposition, (ra, m[ and m ), are not detected. An illustration of electron ionisation of benzene is shown. Also shown is a schematic of the ionisation chamber (ion source). Using a parallel magnetic field can increase the effective path of an electron in the ion source, which increases ionisation efficiency.

The electron transfer in neutral atom-multiply charged ion collisions... 

The products of reactive ion-neutral collisions may be formed in a variety of excited states. Excited products from nonreactive collisions have already been discussed in a previous section. Theoretical calculations of vibrational excitation in the products of symmetric charge-transfer reactions have also been mentioned previously.312-314 The present section deals with excited products from reactive ion-neutral scattering, with special emphasis on luminescence measurements. 

The charged particle collective behaviour (and thus the plasma) exists only if random collision processes do not smear out the coherence of the motion of the charged particles. This means in practice that the frequency of the electron-neutral collisions has to remain smaller than the electron plasma frequency. 

Charge transfer collisions of multiply-charged atomic ions with atomic neutrals... 

This observed pattern of charge transfer and switching processes is consistent with the vertical-transition model (Franck-Condon principle) as discussed by Bearman et al. (1976), who interpreted the cross sections for ionic excitation in low-energy charge-transfer collision between HeJ and some diatomic neutrals. In analogy to that, in the cases of KrJ reactions, it is not the total recombination energy RE(KrJ) = 12.85 eV that is available, but only the effective recombination energy Reeff(KrJ) = 11.91 eV, which is determined, as shown in Fig. 6, by the vertical transition from KrJ to the repulsive state of JCr-Kr at the equilibrium distance f o(Kr2 ) ... 

Plasma conductivity (3-67) is determined by electron density (the contribution of ions will be discussed next) and the frequency of electron-neutral collisions, Ven. The electron density can be found using the Saha equation (3-14) for quasi-equilibrium thermal discharges and from the balance of charged particles in non-equilibrium non-thermal discharges. The frequency of electron-neutral collisions, Ven, is proportional to pressure and can be found numerically for some specific gases from Table 3-1. Relations (3-67) and (3-68) determine the power transferred from the electric field to plasma electrons. This power, calculated per unit volume, is referred to as Joule heating ... 

Vi, accounts for velocity losses due to elastic and charge-exchange collisions of the rrii ion with mi neutral molecules, while the second term, -( f2 + 12)accounts for velocity losses due to collisions of ions with m2 neutrals. The last term accounts for velocity gains for mi ions resulting from charge-exchange collisions of 1712 ions with mi neutrals. 

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