Geoscience Reference
In-Depth Information
The foregoing classification of the ionization processes in thermal collisions of
atoms indicates only some of the possible reaction channels and in this sense is
relative. For example, in the case of collisions of two highly excited atoms with the
comparable ionization potential, six channels of reactions that lead to the formation
of only atomic ions are theoretically possible:
( X e 1 e 2 C Y C
Y e 1 e 2 C X C
( X C C Y e 2 C e 1
X e 1 C Y C C e 2
X e 1 C Y e 2 )
( X C C Y e 1 C e 2
X e 2 C Y C C e 1
In reactions (1.5, 1.6, and 1.7), the indices 1 and 2 refer to the optical electrons of
atoms X and Y, respectively.
Quantitative conclusions about the effectiveness of chemical ionization with
participation of emitting atoms in a broad range of binding energy of the optical
electron by the end of the 1990s were possible primarily for alkali metal atoms
(Klyucharev and Vujnovic 1990 ).
Basic Principles of the Theory
This section discusses the theory of collision ionization, which is characterized by
a variety of methods and approaches developed during the past 20-30 years. We
have skipped over those which by now have become generally accepted and widely
used to describe various physical phenomena in atomic and molecular collisions and
low-temperature plasmas and laser devices in the upper atmosphere and ionosphere,
aeronomy, and astrophysics. However, many questions are yet to receive their final
Semiclassical Approach
If the excitation energy of the atom is greater than the ionization potential of the
particle Y, then the Penning AI process proceeds. Then, for all the finite interatomic
distances the quasi-molecule is found in the autoionizing states, decaying with the
emission of an electron, and the formation of the molecular ion, if its existence is
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