The dynamics of excited state structural relaxation of 4-dimethylaminobenzonitrile (DMABN) and related compounds
The excited state structural relaxation of 4-dimethylaminobenzenes with various para-acceptor substituents having double-band emission, local excited (LE) and charge transfer (CT), has been investigated. Fluorescence measurements at different temperatures and in different solvents have confirmed the...
| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
| Published: |
Hindawi Limited
2006-01-01
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| Series: | International Journal of Photoenergy |
| Online Access: | http://dx.doi.org/10.1155/IJP/2006/81896 |
| Summary: | The excited state structural relaxation of 4-dimethylaminobenzenes with various para-acceptor
substituents having double-band emission, local excited (LE) and
charge transfer (CT), has been investigated. Fluorescence
measurements at different temperatures and in different solvents
have confirmed the existence of viscosity-dependent, temperature,
and polarity-activated relaxation. The kinetics analysis has shown
that the radiative deactivation rate constants of the individual
LE and CT states differ by 7–112-fold. The dipole moment
changes at the excitation for CT states are significantly larger
than those for LE states. The spectral-kinetics behavior of
compounds studied agrees with the models A→A∗→B∗ or A→A∗↔B∗, where A∗ is the local excited planar and B∗ is the relaxed twisted state of the molecule.
The rate constants of the twisted state formation have been
calculated in the temperature range 293–77 K. The activation energies of forward process for compounds studied have
been estimated. |
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| ISSN: | 1110-662X 1687-529X |