6.24). The NeI 2 (E,v E = 1,n E ) state has an intermediate lifetime (s % 1–2 ns),
although the VP decay channel is already available.
The ArI 2 complexes. The T-shaped and linear ArI 2 (X) vdW complexes as well as
Ar n I 2 (X) (n = 2, 3) clusters are formed in a supersonic beam. All the Ar n I 2 (B,
v B ← X,0) (n = 1–3) excitation bands are blue-shifted relative to I 2 (B,v B ← X,0)
bands, and spectral separations between maxima of the I 2 (B,v B = 13-26 ← X,0)
and Ar n I 2 (B,v B = 13-26 ← X,0) bands are * nÁ13.4 cm
−1 [32, 62].
Some spectroscopic characteristics of the ArI 2 (X, B and E) complexes in the Tshaped and linear configurations are given in Table 6.5. The n X = 0 and 1
(E = −237.8 and −213.7 cm
−1 ) vdW levels are localized in the linear well, whereas
n X = 2 one (E = −212 cm
−1 ) is localized in the T-shaped well. The high
(E = 132 cm
−1 above the global (linear) minimum) isomerization barrier presents at
R % 4.92 Å, H % 52.3
o , and lowest vdW vibrational states are expected to be
mostly localized in either linear (n X = = 0, 1) or T-shaped (n X = = 2) wells; the x e
values are equal to 24.0 (linear) and 26.5 (T-shaped) cm
−1 [97].
An analysis of the data on the ArI 2 (B) complexes is given in [18]. The lowest
vdW ArI 2 (B,v B = 21,n B ) levels with E < - 112 cm
−1 energy relative to ArI 2 (B,
v B = 21,n B ) dissociation limit belongs to the T-shaped configuration. The levels with
E % −(10–88) cm
−1 belongs to the linear configuration, and those of E % −(0–10)
cm
−1 , to the free-rotor, probably. Since both ArI 2 (X and B) PESs are similar near
the bottom of the T-shaped well, the Franck–Condon principle implies that the
transition probability from the n X = 2 level has to be largest for n B % 0 and rapidly
decreases with n B [99].
The VP including IVR, as well as the EP of the T-shaped ArI 2 (B) complexes are
well studied. Luminescence of the ArI 2 (B,v B ) VP products lacks for the v B
11
levels since, as it assumed, rate of EP is much larger than that of VP at them.
The VP compete with the EP, and VP efficiencies, Dv B ⩾ 3, show strong oscillations over the v B % 12–26 range for n B = 0-2.
The T-shaped ArI 2 (B) EP is due to the ArI 2 (B– RS), RS ¼ a
0 0
þ
g , a1 g , (1)2 g (and
C1 u , in a less degree) coupling. Oscillations of Franck-Condon densities for the RS
states are out of phase, so total FCD(B/RS) = f(v B ) function can be smooth.
The VP efficiency oscillations are due to IVR in the sparse limit (see an analysis
of the NeCl 2 complexes, Sect. 6.3.2.2, [18, 62, 63] and references). The Dv B ⩾ 3, 2
and 1 channels are energetically available in the E < −180 cm
−1 , % −(180–90)
cm
−1 and % −(90–10) cm
−1 ranges, respectively.
The transition to the linear ArI 2 (B) isomer PES occurs from the n X = 0, 1 vdW
levels localized in the linear well to the left branch of the ArI 2 (B) PES, and continuum excitation spectra correspond to them. Wide ranges of the I 2 (B,v B -Dv B )
states (from v B = 12 to 23 with maximal population at the v B = 18 level for the
ArI 2 (B,v B = 26 ← X,0) transition) are populated. Rotationally cold I 2 (B,v B ) fragments, T rot % 5 K, consistent with direct dissociation from a near-linear geometry
are observed.
234
6 Weakly-Bound Complexes and Clusters
although the VP decay channel is already available.
The ArI 2 complexes. The T-shaped and linear ArI 2 (X) vdW complexes as well as
Ar n I 2 (X) (n = 2, 3) clusters are formed in a supersonic beam. All the Ar n I 2 (B,
v B ← X,0) (n = 1–3) excitation bands are blue-shifted relative to I 2 (B,v B ← X,0)
bands, and spectral separations between maxima of the I 2 (B,v B = 13-26 ← X,0)
and Ar n I 2 (B,v B = 13-26 ← X,0) bands are * nÁ13.4 cm
−1 [32, 62].
Some spectroscopic characteristics of the ArI 2 (X, B and E) complexes in the Tshaped and linear configurations are given in Table 6.5. The n X = 0 and 1
(E = −237.8 and −213.7 cm
−1 ) vdW levels are localized in the linear well, whereas
n X = 2 one (E = −212 cm
−1 ) is localized in the T-shaped well. The high
(E = 132 cm
−1 above the global (linear) minimum) isomerization barrier presents at
R % 4.92 Å, H % 52.3
o , and lowest vdW vibrational states are expected to be
mostly localized in either linear (n X = = 0, 1) or T-shaped (n X = = 2) wells; the x e
values are equal to 24.0 (linear) and 26.5 (T-shaped) cm
−1 [97].
An analysis of the data on the ArI 2 (B) complexes is given in [18]. The lowest
vdW ArI 2 (B,v B = 21,n B ) levels with E < - 112 cm
−1 energy relative to ArI 2 (B,
v B = 21,n B ) dissociation limit belongs to the T-shaped configuration. The levels with
E % −(10–88) cm
−1 belongs to the linear configuration, and those of E % −(0–10)
cm
−1 , to the free-rotor, probably. Since both ArI 2 (X and B) PESs are similar near
the bottom of the T-shaped well, the Franck–Condon principle implies that the
transition probability from the n X = 2 level has to be largest for n B % 0 and rapidly
decreases with n B [99].
The VP including IVR, as well as the EP of the T-shaped ArI 2 (B) complexes are
well studied. Luminescence of the ArI 2 (B,v B ) VP products lacks for the v B
11
levels since, as it assumed, rate of EP is much larger than that of VP at them.
The VP compete with the EP, and VP efficiencies, Dv B ⩾ 3, show strong oscillations over the v B % 12–26 range for n B = 0-2.
The T-shaped ArI 2 (B) EP is due to the ArI 2 (B– RS), RS ¼ a
0 0
þ
g , a1 g , (1)2 g (and
C1 u , in a less degree) coupling. Oscillations of Franck-Condon densities for the RS
states are out of phase, so total FCD(B/RS) = f(v B ) function can be smooth.
The VP efficiency oscillations are due to IVR in the sparse limit (see an analysis
of the NeCl 2 complexes, Sect. 6.3.2.2, [18, 62, 63] and references). The Dv B ⩾ 3, 2
and 1 channels are energetically available in the E < −180 cm
−1 , % −(180–90)
cm
−1 and % −(90–10) cm
−1 ranges, respectively.
The transition to the linear ArI 2 (B) isomer PES occurs from the n X = 0, 1 vdW
levels localized in the linear well to the left branch of the ArI 2 (B) PES, and continuum excitation spectra correspond to them. Wide ranges of the I 2 (B,v B -Dv B )
states (from v B = 12 to 23 with maximal population at the v B = 18 level for the
ArI 2 (B,v B = 26 ← X,0) transition) are populated. Rotationally cold I 2 (B,v B ) fragments, T rot % 5 K, consistent with direct dissociation from a near-linear geometry
are observed.
234
6 Weakly-Bound Complexes and Clusters