Excited-State Dynamics in Nitro-Naphthalene Derivatives:
Intersystem Crossing to the Triplet Manifold in Hundreds of Femtoseconds
R. Aaron Vogt
Christian Reichardt
Carlos E. Crespo-Hernández
10.1021/jp405656n.s001
https://acs.figshare.com/articles/journal_contribution/Excited_State_Dynamics_in_Nitro_Naphthalene_Derivatives_Intersystem_Crossing_to_the_Triplet_Manifold_in_Hundreds_of_Femtoseconds/2392138
Femtosecond
transient absorption experiments and density functional
calculations are presented for 2-methyl-1-nitronaphthalene, 2-nitronaphthalene,
and 1-nitronaphthalene in cyclohexane and acetonitrile solutions.
Excitation of 2-methyl-1-nitronaphthalene at 340 nm populates the
Franck–Condon singlet state, which bifurcates into two barrierless
decay channels with sub-200-fs lifetimes. The primary decay channel
connects the Franck–Condon singlet excited state with a receiver
triplet state, whereas the second, minor channel involves conformational
relaxation to populate an intramolecular charge-transfer state, as
previously reported for 1-nitronaphthalene (J. Chem. Phys. 2009, 113, 224518). Conversely,
the experimental and computational data for 2-nitronaphthalene shows
that almost the entire Franck–Condon singlet excited-state
population intersystem crosses to the triplet state in less than 200
fs due to a sizable energy barrier of ca. 5 kcal/mol that must be
surmounted to access the intramolecular charge-transfer state. Our
results lend support to the idea that the probability of population
transfer to the triplet manifold in these nitronaphthalene derivatives
is controlled not only by the small energy gap between the Franck–Condon
singlet excited state and the receiver triplet state but also by the
region of configuration space sampled in the singlet excited-state
potential energy surface at the time of excitation. It is proposed
that the ultrafast intersystem crossing dynamics in these nitronaphthalene
molecules most likely occurs between nonequilibrated excited states
in the strongly nonadiabatic regime.
2013-08-01 00:00:00
340 nm populates
barrierless decay channels
nitronaphthalene molecules
energy surface
Franck
acetonitrile solutions
nonadiabatic regime
configuration space
ultrafast intersystem
energy barrier
decay channel
triplet manifold
200 fs
absorption experiments
nitronaphthalene derivatives
population transfer
triplet state
receiver triplet state
singlet
Triplet Manifold
energy gap