Intermolecular pyrene excimer formation in zeolites. Decay parameters and ground-state association

1984 ◽  
Vol 106 (25) ◽  
pp. 7705-7710 ◽  
Author(s):  
Steven L. Suib ◽  
Athanasios Kostapapas
Keyword(s):  
Ground State ◽  
State Association ◽  
Excimer Formation ◽  
Decay Parameters ◽  
Pyrene Excimer Formation

Surface photochemistry: the effect of surface modification on the photophysics of naphthalene and pyrene adsorbed on silica gel

1984 ◽  
Vol 62 (7) ◽  
pp. 1279-1286 ◽  
Author(s):  
Richard K. Bauer ◽  
Paul de Mayo ◽  
Lalgudi V. Natarajan ◽  
William R. Ware
Keyword(s):  
Heat Treatment ◽  
Silica Gel ◽  
Ground State ◽  
Emission Spectra ◽  
Fluorescence Decay ◽  
Relative Importance ◽  
Broad Emission ◽  
State Association ◽  
Excimer Formation ◽  
Effect Of Surface

The influence of heat treatment and of added coadsorbates on the surface photophysics of pyrene and naphthalene adsorbed on silica gel is reported. When the silica gel surface is partially dehydroxylated, the distribution of pyrene or naphthalene is inhomogeneous, as indicated by multiexponential fluorescence decay and broad emission spectra. Addition of polar coadsorbates renders the surface more homogeneous with singlet lifetimes approaching solution values. The pretreatment and addition of coadsorbates, in the case of pyrene, also influence the relative importance of dynamic excimer formation vis-a-vis ground state association.

scholarly journals Unfolding of Helical Poly(L-Glutamic Acid) in N,N-Dimethylformamide Probed by Pyrene Excimer Fluorescence (PEF)

Polymers ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1690
Author(s):  
Weize Yuan ◽  
Remi Casier ◽  
Jean Duhamel
Keyword(s):  
Glutamic Acid ◽  
Local Density ◽  
Guanidine Hydrochloride ◽  
Racemic Mixture ◽  
Excimer Fluorescence ◽  
Excimer Formation ◽  
Blob Model ◽  
Α Helix ◽  
The Relationship ◽  
Pyrene Excimer Formation

The denaturation undergone by α–helical poly(L-glutamic acid) (PLGA) in N,N-dimethylformamide upon addition of guanidine hydrochloride (GdHCl) was characterized by comparing the fluorescence of a series of PLGA constructs randomly labeled with the dye pyrene (Py-PLGA) to that of a series of Py-PDLGA samples prepared from a racemic mixture of D,L-glutamic acid. The process of pyrene excimer formation (PEF) was taken advantage of to probe changes in the conformation of α–helical Py-PLGA. Fluorescence Blob Model (FBM) analysis of the fluorescence decays of the Py-PLGA and Py-PDLGA constructs yielded the average number (<Nblob>) of glutamic acids located inside a blob, which represented the volume probed by an excited pyrenyl label. <Nblob> remained constant for randomly coiled Py-PDLGA but decreased from ~20 to ~10 glutamic acids for the Py-PLGA samples as GdHCl was added to the solution. The decrease in <Nblob> reflected the decrease in the local density of PLGA as the α–helix unraveled in solution. The changes in <Nblob> with GdHCl concentration was used to determine the change in Gibbs energy required to denature the PLGA α–helix in DMF. The relationship between <Nblob> and the local density of macromolecules can now be applied to characterize the conformation of macromolecules in solution.

Einfluß der Deuterierung auf die Excimerenkinetik des Pyrens

1976 ◽  
Vol 31 (8) ◽  
pp. 990-994
Author(s):  
Günther Heidt
Keyword(s):  
Partition Function ◽  
Rate Constants ◽  
Formation Rate ◽  
Kinetic Constants ◽  
Theoretical Expectation ◽  
Excimer Emission ◽  
Anomalous Effect ◽  
Excimer Formation ◽  
Pyrene Excimer Formation

AbstractThe effect of deuteration on all six photophysical and kinetic constants of pyrene excimer formation is investigated. The rate constants of monomer and excimer emission and the rate of dissociation of the excimer are not affected by deuteration. The increase of the radiationless deactivation of the monomer (anomalous effect) agrees with the theoretical expectation. The radiationless deactivation of the excimer at various temperatures shows no effect and therefore does not take place via the excimer triplet. The decrease of the excimer formation rate can be explained by the effect of deuteration on the partition function and hence on the entropy.

The effect of pressure on excimer formation

1965 ◽  
Vol 18 (7) ◽  
pp. 977 ◽  
Author(s):  
H Seidel ◽  
BK Selinger
Keyword(s):  
Excited State ◽  
Hydrostatic Pressure ◽  
Molar Volume ◽  
Aromatic Hydrocarbons ◽  
Ground State ◽  
Dominant Factor ◽  
Effect Of Pressure ◽  
Excimer Formation ◽  
Ground State Molecule ◽  
True Equilibrium

The formation of excited dimers by aromatic hydrocarbons in solution was found to be influenced by hydrostatic pressure. The increase in the viscosity of the solvent with pressure is the dominant factor for the more stable excited dimers and this causes a decrease in the amount of dimer with increasing pressure. Where there is a true equilibrium between excited dimer and monomer an increase in pressure causes an increase in dimer concentration. The change in molar volume for the formation of an excited dimer of 1,6-dimethylnaphthalene from a ground state molecule and one in the excited state was found to be -20 cm3 mole-1, representing a 10% reduction.

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