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Solvent dependence of pyrene monomer and excimer fluorescence quenching by heavy atoms
Author(s) -
AbuZeid MohyiEldin M.
Publication year - 2009
Publication title -
international journal of quantum chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.484
H-Index - 105
eISSN - 1097-461X
pISSN - 0020-7608
DOI - 10.1002/qua.560060629
Subject(s) - excimer , pyrene , quenching (fluorescence) , chemistry , monomer , solvent , molecule , fluorescence , analytical chemistry (journal) , diffusion , photochemistry , polymer , thermodynamics , organic chemistry , physics , quantum mechanics
Two independent methods have been used for the determination of pyrene monomer ( M *) and excimer ( D *) quenching rate parameters in eight common solvents ranging in viscosities between 0.3 and 5.9 cP. Heavy atoms (CCl 4 ) were used as quenchers. The discrepancies between the values of the quenching rate parameters reported in the two methods have been explained as due to formation of complexes between the pyrene molecule and CCl 4 molecules as a result of using a more intense source, which might lead to larger values of the quenching rate parameters. Assuming that the quenching processes are diffusion‐controlled ones, the probabilities of the effective collisions between M * or D * and CCl 4 ( P P or P P , respectively) were then calculated. These values were found to depend on the nature of the solvents used and in particular on their viscosities (η). At low values of η, the average values of P P and P P are approximately the same for each solvent used. For intermediate values of η, P P becomes much larger than P P . Finally for relatively large values of η, P P becomes much smaller than P P .