Penning systems ionization cross sections

Figure 19. Deviation of sum of partial cross sections from total ionization cross section, normalized to total ionization cross section, is plotted against the collision energy. All cross sections are calculated on basis of description of Penning process by local complex potential. Deviation is measure of inconsistency of their desorption for case of system He(2 S )-H.

According to the theoretical investigations by Nakamura [126-128] and Miller [129], the collisional energy dependence of these processes can be calculated if the interaction potential V(R) for the system He(2 S)-M and the autoionization rate r K)jh from the intermediate quasi-molecule [He(2 S)M] to the resulting quasi-molecular ion [HeM] are known. For example, by the classical formula of Miller [129], we have theoretical cross sections for Penning ionization as ... 

A little more complicated system is the de-excitation of He(2 P) by Ne, where the deexcitation is dominated by the excitation transfer and only a minor contribution from the Penning ionization is involved. The experimental cross section obtained by the pulse radiolysis method, together with the numerical calculation for the coupled-channel radial Schrodinger equation, has clearly provided the major contribution of the following excitation transfer processes to the absolute de-excitation cross sections [151] (Fig. 15) ... 

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