first 40–50 fs. The largest SOC is predicted between the lowest
1 MLCT and its
associated triplet state. The importance of solvation dynamics is also emphasized.
The drawback of this pioneering promising approach is the limited number of
trajectories and the qualitative estimation of the SOC, the value of which should be
determined quantitatively on the fly as well. However, this strategy opens the route
to new applications in large transition metal complexes as soon as the electronic
structure can be described correctly by means of TD-DFT.
5.3 Ultra-Fast Luminescence Decay in [Re (Br)(CO) 3 (bpy)]
Complexes
In this very recent application we focus on the excited states decay of [Re (Br)
(CO) 3 (bpy)] within the first 500 fs by means of non-adiabatic quantum dynamics
including spin vibronic couplings within the linear approach and based on TD-DFT
energies and frequencies [122]. For this purpose we have constructed a model
Hamiltonian including five electronic states, namely S 2 which absorbs at 400 nm,
S 1 and the three lowest triplet states T 3 , T 2 , and T 1 (Scheme 6) and up to six
vibrational normal modes. The five states are coupled by SOC and vibronically. The
SOC values are assumed to be constant as functions of the nuclear displacements.
This is justified in a first approximation, for the bromide-substituted complex in
which the calculated SOC remain nearly constant as function of the Re–Br
stretching bond [121]. The calculated emission wavelengths of these five excited
states, including SOC, are reported in Table 6 (Sect. 4.3). To validate the PES
generated within the LVC harmonic model starting from Franck–Condon geometry, we have computed the TD-DFT PES as function of the mass and frequency
weighted Re–Br stretching normal mode [121].
Scheme 6 proposes a qualitative correlation between the experimental data
obtained from time-resolved luminescence spectroscopy and the state diagram
built on the basis of the calculated emission wavelengths reported in Table 6
(Sect. 4.3).
The purpose of the simulation based on wave packet propagations with multiconfiguration time-dependent Hartree MCTDH [131, 132] is to recover the
populations of the involved electronic states as function of time within the first
500 fs and to interpret the ultra-fast luminescent decay observed
experimentally [120].
The interplay between SOC and vibronic coupling, based on symmetry rules,
controlled entirely the ISC process. Indeed, when including SOC matrix elements
together with four normal modes of symmetry a
0 , namely two modes associated
with the Re–Br stretching and two modes associated with the Re–CO stretching, we
Absorption Spectroscopy, Emissive Properties, and Ultrafast Intersystem. . .
405
1 MLCT and its
associated triplet state. The importance of solvation dynamics is also emphasized.
The drawback of this pioneering promising approach is the limited number of
trajectories and the qualitative estimation of the SOC, the value of which should be
determined quantitatively on the fly as well. However, this strategy opens the route
to new applications in large transition metal complexes as soon as the electronic
structure can be described correctly by means of TD-DFT.
5.3 Ultra-Fast Luminescence Decay in [Re (Br)(CO) 3 (bpy)]
Complexes
In this very recent application we focus on the excited states decay of [Re (Br)
(CO) 3 (bpy)] within the first 500 fs by means of non-adiabatic quantum dynamics
including spin vibronic couplings within the linear approach and based on TD-DFT
energies and frequencies [122]. For this purpose we have constructed a model
Hamiltonian including five electronic states, namely S 2 which absorbs at 400 nm,
S 1 and the three lowest triplet states T 3 , T 2 , and T 1 (Scheme 6) and up to six
vibrational normal modes. The five states are coupled by SOC and vibronically. The
SOC values are assumed to be constant as functions of the nuclear displacements.
This is justified in a first approximation, for the bromide-substituted complex in
which the calculated SOC remain nearly constant as function of the Re–Br
stretching bond [121]. The calculated emission wavelengths of these five excited
states, including SOC, are reported in Table 6 (Sect. 4.3). To validate the PES
generated within the LVC harmonic model starting from Franck–Condon geometry, we have computed the TD-DFT PES as function of the mass and frequency
weighted Re–Br stretching normal mode [121].
Scheme 6 proposes a qualitative correlation between the experimental data
obtained from time-resolved luminescence spectroscopy and the state diagram
built on the basis of the calculated emission wavelengths reported in Table 6
(Sect. 4.3).
The purpose of the simulation based on wave packet propagations with multiconfiguration time-dependent Hartree MCTDH [131, 132] is to recover the
populations of the involved electronic states as function of time within the first
500 fs and to interpret the ultra-fast luminescent decay observed
experimentally [120].
The interplay between SOC and vibronic coupling, based on symmetry rules,
controlled entirely the ISC process. Indeed, when including SOC matrix elements
together with four normal modes of symmetry a
0 , namely two modes associated
with the Re–Br stretching and two modes associated with the Re–CO stretching, we
Absorption Spectroscopy, Emissive Properties, and Ultrafast Intersystem. . .
405