Geoscience Reference
In-Depth Information
2000
p
1500
f
1000
s
¢
d
500
+
Sr
0
5
10
15
20
25
n
Fig. 1.20
Identical with Fig.
1.19
for the case of single-charged strontium ions
The ionization in collisions of two Rydberg alkali atoms in the
n
2
P state was
studied by Bezuglov et al. (
1997
), taking into account the influence of the interaction
of close configurations
n
2
P,
n
2
S, and (
n
C
1)
2
S on the efficiency of the process:
A .nl/
C
A .nl/
!
A .n
1
l
1
/
C
A
C
C
e
:
(1.72)
with the transitions to the nearest (over energy) level of the ion state, in the case
when the energy of
nl
!
n
1
l
1
transition into the lower
n
1
l
1
state exceeds the bound
energy of the
nl
state of another atom (near-threshold ionization). High efficiency
of the reaction (
1.72
) at large interatomic distances takes place as a result of the
dipole-dipole interaction, which in this case is the most effective of all multi-
pole interactions. Results of the numerical calculation of the cross section of the
molecular ion formation process are shown in Fig.
1.21
.
The cross section oscillates with respect to
n
within the principal quantum
numbers 7 <
n
< 26, which is associated with the oscillations depending on the
frequency of the intraatomic transitions. The weak components in the electronic
spectra of the reaction under certain conditions can become apparent, which
corresponds to the forbidden in the dipole-dipole approximation (
L
D˙
1) optical
transitions ŒA.nP/
C
A .nP/
!
ŒA .nS/
C
A ..n
C
1/ S/, induced by the inter-
configuration interaction.
