High pressure study of viscosity effects on the luminescence of tetracyanobenzene EDA complexes
High pressure fluorescence studies fron 0--10 kbar have been performed on electron donor--acceptor (EDA) complexes of s-tetracyanobenzene (TCNB) with a series of aromatic hydrocarbons. Four solvents were used, 2,2,4,4,6,8,8 heptamethylnonane (HMN), methylcyclohexane (MCH), 2,6,10,14 tetramethylpentadecane (TMPD), and a mixture of MCH and HMN. A viscosity range from 0.006 to 10 000 poise was covered at constant temperature. As pressure (viscosity) increased the fluorescence spectrum shifted from one dominated by emission from the equilibrium (EQ) excited singlet state to one dominated by Franck--Condon (FC) singlet emission. Lifetime measurements for the complexes of o-xylene and p-xylene with TCNB as well as one mesitylene complex yielded the two radiative rates (k/sub EQ/ and k/sub FC/) as well as the rate of internal conversion from FC to the EQ excited state to (k/sub IC/). The results are discussed in terms of the rate of relaxation of the solvent compared with the rate k/sub FC/. It was found that k/sub IC/ correlated very well with the solvent viscosity.
- Research Organization:
- School of Chemical Sciences and Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801
- OSTI ID:
- 6797741
- Journal Information:
- J. Chem. Phys.; (United States), Vol. 74:6
- Country of Publication:
- United States
- Language:
- English
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