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Updated: Jan 20, 2026

Molecular Diffusion in Plasma Membranes of Primary Lymphocytes Measured by Fluorescence Correlation Spectroscopy
Published on: February 1, 2017
Study on fluorescence spectroscopy of PAHs with different molecular structures using laser-induced fluorescence (LIF)
Yiran Zhang1, Peng Liu2, Youping Li1
1Key Laboratory for Power Machinery and Engineering of Ministry of Education, School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China.
Abstract:
Laser-induced fluorescence (LIF) is an effective technique for non-intrusive and on-line measurement of PAHs in sooting flames but it is still need further investigation due to the complexity of PAH fluorescence characteristics. Therefore, in-depth investigations on the fluorescence spectroscopy of PAHs with different molecular structures are relevant. In this study, we investigated the fluorescence spectrum characteristics of 13 gas-phase PAHs using LIF measurement and time-dependent density functional theory (TD-DFT) calculation. The experimental results showed that the fluorescence emission wavelengths increased with more aromatic (benzenoid) rings, but this relationship no longer existed when the PAH molecules contain the five-membered ring structures. The TD-DFT calculation showed that the fluorescence emission wavelength ranges of PAHs with different molecular structures were dominantly determined by the electronic structures of highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) and their energy gaps. It was found that the saturated aliphatic branched chains (methyl and ethyl) only slightly influenced the LIF spectra, while the unsaturated aliphatic branched chains (ethenyl and ethynyl) caused remarkable redshifts. The TD-DFT results indicated that the aliphatic branched chains changed the electric structures of HOMO and LUMO of the core aromatic rings, and then influence the fluorescence emission wavelength ranges.
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