Preface
Molecules in the electronic excited state take important roles in various processes.
For the excited molecules in condensed phase, however, there exist general
restrictions in the efficient utilization of light energies. First, higher electronically
excited states of rather large molecules very rapidly relax to lower electronic states
(Kasha’s rule), and some portion of the photon energy is diminished in this
relaxation. Second, a large number of the molecules excited in assemblies undergo
fast annihilation, and only a small number of excited state molecules can remain,
leading to the loss of the number of photons absorbed in the system. In addition, the
electronic state accessible by the photoabsorption is limited by the optical selection
rule, and we cannot access various dark electronic excited states of molecules.
These restrictions have confined most of the photochemical responses into the
framework of “one-photon and one-molecule outcomes in the lowest excited state”
and have been preventing us from efficiently and cooperatively utilizing a number
of photons and excited molecules.
To explore principles to realize responses induced by a number of photons and
excited molecules (photosynergetic responses) beyond the limit of “one-photon and
one-molecule outcomes in the lowest excited state” leading to the new paradigm,
we organized a Grant-in-Aid for Scientific Research (Kakenhi) Project on
Innovative Areas “Photosynergetics: Application of Cooperative Excitation into
Innovative Molecular Systems with High-Order Photofunctions” (Hiroshi
Miyasaka, project leader and 34 research groups) from 2014 to 2019, supported by
the Ministry of Education, Culture, Sports, Science and Technology, Japan.
The research project focused on the three subjects for the realization of the
photosynergetic responses.
(1) Exploration and elucidation of reactions from higher electronic excited states,
modulation of electronic states by the local field and effective utilization of
multiple excitons.
(2) Development of high-order photofunctions based on the synergetic action of
photoresponsive molecules.
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Molecules in the electronic excited state take important roles in various processes.
For the excited molecules in condensed phase, however, there exist general
restrictions in the efficient utilization of light energies. First, higher electronically
excited states of rather large molecules very rapidly relax to lower electronic states
(Kasha’s rule), and some portion of the photon energy is diminished in this
relaxation. Second, a large number of the molecules excited in assemblies undergo
fast annihilation, and only a small number of excited state molecules can remain,
leading to the loss of the number of photons absorbed in the system. In addition, the
electronic state accessible by the photoabsorption is limited by the optical selection
rule, and we cannot access various dark electronic excited states of molecules.
These restrictions have confined most of the photochemical responses into the
framework of “one-photon and one-molecule outcomes in the lowest excited state”
and have been preventing us from efficiently and cooperatively utilizing a number
of photons and excited molecules.
To explore principles to realize responses induced by a number of photons and
excited molecules (photosynergetic responses) beyond the limit of “one-photon and
one-molecule outcomes in the lowest excited state” leading to the new paradigm,
we organized a Grant-in-Aid for Scientific Research (Kakenhi) Project on
Innovative Areas “Photosynergetics: Application of Cooperative Excitation into
Innovative Molecular Systems with High-Order Photofunctions” (Hiroshi
Miyasaka, project leader and 34 research groups) from 2014 to 2019, supported by
the Ministry of Education, Culture, Sports, Science and Technology, Japan.
The research project focused on the three subjects for the realization of the
photosynergetic responses.
(1) Exploration and elucidation of reactions from higher electronic excited states,
modulation of electronic states by the local field and effective utilization of
multiple excitons.
(2) Development of high-order photofunctions based on the synergetic action of
photoresponsive molecules.
v