scholarly journals Exploration of minimum energy conical intersection structures of small polycyclic aromatic hydrocarbons: toward an understanding of the size dependence of fluorescence quantum yields

2015 ◽  
Vol 17 (35) ◽  
pp. 22561-22565 ◽  
Author(s):  
Yu Harabuchi ◽  
Tetsuya Taketsugu ◽  
Satoshi Maeda
Keyword(s):  
Polycyclic Aromatic Hydrocarbons ◽  
Aromatic Hydrocarbons ◽  
Energy Barrier ◽  
Size Dependence ◽  
Minimum Energy ◽  
Conical Intersection ◽  
Quantum Yields ◽  
Fluorescence Quantum Yields ◽  
Polycyclic Aromatic

A correlation between the fluorescence quantum yields and the energy barrier to the conical intersection region was discovered for five small PAHs.

Determination of Polycyclic Aromatic Hydrocarbons in the Presence of Humic Acid in water

2016 ◽  
Vol 70 (9) ◽  
pp. 1520-1528 ◽  
Author(s):  
Ruifang Yang ◽  
Nanjing Zhao ◽  
Xue Xiao ◽  
Shaohui Yu ◽  
Jianguo Liu ◽  
...  
Keyword(s):  
Polycyclic Aromatic Hydrocarbons ◽  
Humic Acid ◽  
Aromatic Hydrocarbons ◽  
Fluorescence Quantum Yield ◽  
Quantum Yields ◽  
Fluorescence Quantum Yields ◽  
Polycyclic Aromatic ◽  
Pahs Concentration ◽  
Test Sets

The presence of humic acid (HA) makes it extremely difficult to determine and quantify accurately polycyclic aromatic hydrocarbons (PAHs) in aquatic environment because of their complex and strong interaction. To solve this problem, a new method was developed in this work through the combination of PARAFAC and fluorescence spectroscopy, which mainly includes: (1) the fluorescence quantum yield acquisition of PAHs with and without HA by PARAFAC; (2) the  concentration score correction of PAHs in validation and test sets using the fluorescence quantum yields; and (3) the prediction of PAHs concentration in the validation and test sets in the presence of HA by corrected concentration. Using this method, the PAHs concentration on the level of µg L−1 in the test samples with HA of 2.5 mg/L and 5.0 mg/L can be successfully predicted with the root mean square error below 0.15 µg L−1, relative error of prediction below 4% for validation samples, recoveries of each PAH between 82.5% and 102.6% for test samples.

scholarly journals The origin of the solvent dependence of fluorescence quantum yields in dipolar merocyanine dyes

2019 ◽  
Vol 10 (48) ◽  
pp. 11013-11022 ◽  
Author(s):  
Joscha Hoche ◽  
Alexander Schulz ◽  
Lysanne Monika Dietrich ◽  
Alexander Humeniuk ◽  
Matthias Stolte ◽  
...  
Keyword(s):  
Activation Energy ◽  
Energy Barrier ◽  
Conical Intersection ◽  
Quantum Yields ◽  
Fluorescence Lifetimes ◽  
Activation Energy Barrier ◽  
Polar Solvents ◽  
Fluorescence Quantum Yields ◽  
Solvent Dependence ◽  
Merocyanine Dyes

An increasing activation energy barrier to a conical intersection was identified as the reason for higher fluorescence lifetimes and quantum yields for merocyanines in polar solvents.

Photophysical and Photochemical Studies of Polycyclic Aromatic Hydrocarbons in Solutions Containing Tetrachloromethane. III. Photochemical Interaction of Excited Polycyclic Aromatic Hydrocarbons with Tetrachloromethane in Two-Component Mixtures

1991 ◽  
Vol 46 (3) ◽  
pp. 259-264 ◽  
Author(s):  
Wieslaw M. Wiczk ◽  
Tadeusz Latowski
Keyword(s):  
Polycyclic Aromatic Hydrocarbons ◽  
Binary Mixtures ◽  
Aromatic Hydrocarbons ◽  
Kinetic Scheme ◽  
Intermediate Stage ◽  
Quantum Yields ◽  
Chemical Transformations ◽  
Hydrocarbon Solvent ◽  
Two Component ◽  
Polycyclic Aromatic

AbstractIn the photoreactions of polycyclic aromatic hydrocarbons with tetrachloromethane in binary mixtures of tetrachloromethane with cyclohexane, benzene and acetonitrile, both the quenching of the fluorescence and the photoreactions run through an intermediate stage which is an exciplex of the excited hydrocarbon with tetrachloromethane. Abnormal quantum yields of the hydrocarbon decrease are interpreted in terms of the appearance of a new reaction channel via a triplex consisting of the excited hydrocarbon, solvent and tetrachloromethane. The photoreaction is quenched by diphenylpicrylhydrazyl, thus suggesting the radical nature of the chemical transformations. A kinetic scheme is suggested for the photophysical and photochemical processes describing the observed phenomena.

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