resonance are reduced due to the large value of V 1,2 , many rotational levels are
populated, not only B,v B = 0, 3, but also other vibrational levels. The same feature is
observed in the NO(a
4 P ! b
4 R
−
, v b = 3–5) CINATs between quartet states, since
the forbiddance of this transition is much weaker than in the processes considered
above. But the fee for this is ‘heavy’: the gateway model is not applicable in this
case. This type of process needs additional researches. In the author’s opinion, a
decent model that adequately describes perturbation-facilitated processes in the case
of large quantities of interaction matrix elements has not yet been created.
5.5.2 Perturbation-Irrelevant Transitions
Now we will consider some experimental data concerning processes indifferent to
perturbations and models that explain the observed features. We will move from
simple to complex.
5.5.2.1 Collision-Induced Predissociation of the I 2 B0
þ
u
À
Á
State
Let us start with the most, perhaps, the oldest and most simple model of these
processes. It can describe CINATs only qualitatively. A collision leads to the
deformation of the electron shells, an appearance of electric and magnetic fields
and, therefore, perturbations induced by them (Stark or Zeeman effects) [22],
p. 418. These perturbations may cause CINATs. The collision-induced predissociation (CIP) of the I 2 (B0
þ
u ) state
I 2 B; v B ; J B
ð
Þ À !
M I 2 ðRSÞ ! I
2 P 3=2
À
Á þ I
2 P 3=2
À
Á
ð5:5:7Þ
(RS means repulsive state (states)) is an example of such processes. The CIP perturbation operator can be obtained in the same way as for the van der Waals (vdW)
interactions (see Sect. 6.3); its cross-section is [27]:
r CIP $ l
1=2 I M a M =R
3
C ;
here l is the reduced mass, I M and a M are the M ionization potential, and polarizability, R c = (1/2)Á(r M + r I 2 ðBÞ ) is a half of the M and I 2 (B) gas-kinetic diameter
sum. The form of the perturbation operator determines the selection rules. If the
transition is caused by an induced electric field, the perturbation operator has the
same symmetry type as that of transition dipole moment. Accordingly, the selection
rules for the CINAT become the same as for the optical ones, in particular, the strict
selection rule for intramolecular perturbations of homonuclear molecules:
174
5 Energy Transfer in Collisions
populated, not only B,v B = 0, 3, but also other vibrational levels. The same feature is
observed in the NO(a
4 P ! b
4 R
−
, v b = 3–5) CINATs between quartet states, since
the forbiddance of this transition is much weaker than in the processes considered
above. But the fee for this is ‘heavy’: the gateway model is not applicable in this
case. This type of process needs additional researches. In the author’s opinion, a
decent model that adequately describes perturbation-facilitated processes in the case
of large quantities of interaction matrix elements has not yet been created.
5.5.2 Perturbation-Irrelevant Transitions
Now we will consider some experimental data concerning processes indifferent to
perturbations and models that explain the observed features. We will move from
simple to complex.
5.5.2.1 Collision-Induced Predissociation of the I 2 B0
þ
u
À
Á
State
Let us start with the most, perhaps, the oldest and most simple model of these
processes. It can describe CINATs only qualitatively. A collision leads to the
deformation of the electron shells, an appearance of electric and magnetic fields
and, therefore, perturbations induced by them (Stark or Zeeman effects) [22],
p. 418. These perturbations may cause CINATs. The collision-induced predissociation (CIP) of the I 2 (B0
þ
u ) state
I 2 B; v B ; J B
ð
Þ À !
M I 2 ðRSÞ ! I
2 P 3=2
À
Á þ I
2 P 3=2
À
Á
ð5:5:7Þ
(RS means repulsive state (states)) is an example of such processes. The CIP perturbation operator can be obtained in the same way as for the van der Waals (vdW)
interactions (see Sect. 6.3); its cross-section is [27]:
r CIP $ l
1=2 I M a M =R
3
C ;
here l is the reduced mass, I M and a M are the M ionization potential, and polarizability, R c = (1/2)Á(r M + r I 2 ðBÞ ) is a half of the M and I 2 (B) gas-kinetic diameter
sum. The form of the perturbation operator determines the selection rules. If the
transition is caused by an induced electric field, the perturbation operator has the
same symmetry type as that of transition dipole moment. Accordingly, the selection
rules for the CINAT become the same as for the optical ones, in particular, the strict
selection rule for intramolecular perturbations of homonuclear molecules:
174
5 Energy Transfer in Collisions