Geoscience Reference

In-Depth Information

Fig. 1.2
Potential curves for the molecular ion XY
C
and the quasi-molecular XY
*
. The excitation

energy of the atom Y
*

is smaller than the ionization potential of the atom X

preconditions do not violate, can be estimated from the ratio of the de Broglie

wavelength of the atom and the characteristic atomic size,
a
0
. All this has led to the

development of Penning electron spectroscopy as a new direction of experimental

research.

If the excitation energy X
*
is smaller than the Y ionization potential, than there

are two possibilities: reaction (1.8) and (1.9) (in the diabatic representation). The

first case takes place when the potential curves of the quasi-molecule U
ˇ
and the

molecular ion
U
i
do not overlap (Fig.
1.2
). In this case, the transition occurs because

of the nonadiabatic coupling of the electron and nuclear motions in a wide range of

interatomic distances
R
, when they approach, and the potential curves of Rydberg

states of the quasi-molecule X
**
Y are the Coulomb condensation. The second case

corresponds to the situation when, in the vicinity of the point
R
c
, the potential

curve XY
*
, and the dissociative term (diabatic picture) intersects a set of curves

of the Rydberg and ion
U
i
terms (Fig.
1.3
). When going to the region of interatomic

distances
R
<
R
c
,thetermXY
*
becomes autoionization. Consequently, the reaction

of the AI here is essentially a multichannel process, as occurs with the participation

continuums of the Rydberg, dissociative, and ionized states (see Figs.
1.2
,
1.3
). As

a result of the direct relationship of the Rydberg XY
**
, the dissociative X
*

C
Y,

the intermediate valence X
*
Y, and the ionic X
C
Y
configurations, under the atom

collisions are possible not only autoionization, but inelastic transitions, that can be

accompanied with the increase (or decrease) of the initial atom excitation energies.

Analysis of the discrete level interaction with the states of the continuum and

the infinite sequence of the Coulomb levels was carried out (Demkov and Komarov

1966
). Strictly speaking, the problem of multiple transitions (associated with the