title: Detection of Explosive Vapors: The Roles of Exciton and Molecular Diffusion in Real-Time Sensing.
abstract: Time-resolved quartz crystal microbalance with in situ fluorescence measurements are used to monitor the sorption of the nitroaromatic (explosive) vapor, 2,4-dinitrotoluene (DNT) into a porous pentiptycene-containing poly(phenyleneethynylene) sensing film. Correlation of the nitroaromatic mass uptake with fluorescence quenching shows that the analyte diffusion follows the Case-II transport model, a film-swelling-limited process, in which a sharp diffusional front propagates at a constant velocity through the film. At a low vapor pressure of DNT of ≈16 ppb, the analyte concentration in the front is sufficiently high to give an average fluorophore-analyte separation of ≈1.5 nm. Hence, a long exciton diffusion length is not required for real-time sensing in the solid state. Rather the diffusion behavior of the analyte and the strength of the binding interaction between the analyte and the polymer play first-order roles in the fluorescence quenching process.
authors: Centre for Organic Photonics & Electronics, School of Chemistry and Molecular Biosciences, School of Mathematics and Physics, The University of Queensland, Brisbane, Queensland, 4072, Australia.
authors: Mohammad A
authors: MA
authors: Ali
authors: Centre for Organic Photonics & Electronics, School of Chemistry and Molecular Biosciences, School of Mathematics and Physics, The University of Queensland, Brisbane, Queensland, 4072, Australia.
authors: Safa
authors: S
authors: Shoaee
authors: Centre for Organic Photonics & Electronics, School of Chemistry and Molecular Biosciences, School of Mathematics and Physics, The University of Queensland, Brisbane, Queensland, 4072, Australia.
authors: Shengqiang
authors: S
authors: Fan
authors: Centre for Organic Photonics & Electronics, School of Chemistry and Molecular Biosciences, School of Mathematics and Physics, The University of Queensland, Brisbane, Queensland, 4072, Australia.
authors: Paul L
authors: PL
authors: Burn
authors: Centre for Organic Photonics & Electronics, School of Chemistry and Molecular Biosciences, School of Mathematics and Physics, The University of Queensland, Brisbane, Queensland, 4072, Australia.
authors: Ian R
authors: IR
authors: Gentle
authors: Centre for Organic Photonics & Electronics, School of Chemistry and Molecular Biosciences, School of Mathematics and Physics, The University of Queensland, Brisbane, Queensland, 4072, Australia.
authors: Paul
authors: P
authors: Meredith
authors: Centre for Organic Photonics & Electronics, School of Chemistry and Molecular Biosciences, School of Mathematics and Physics, The University of Queensland, Brisbane, Queensland, 4072, Australia.
authors: Paul E
authors: PE
authors: Shaw
keywords: conjugated polymers; explosives; fluorescence; sensors; time-resolved spectroscopy