Molecular versus exciton diffusion in fluorescence-based explosive vapour sensors

Ali, M. A.; Geng, Yanfang; Cavaye, Hamish; Burn, Paul L.; Gentle, Ian R.; Meredith, Paul; Shaw, Paul E.

doi:10.1039/c5cc06367a

Cited by 16 publications

(22 citation statements)

References 29 publications

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“…When trace-level vapours of explosives encounter an organic fluorescent sensor, molecules from the vapour are absorbed into the film and modify its light-emitting properties [13,14]. Specifically, an electron is transferred from a photogenerated exciton in the sensor to a sorbed nitroaromatic molecule, which results in fluorescence quenching and indicates the presence of explosives in the surrounding environment.…”

Section: Introductionmentioning

confidence: 99%

Thermal Desorption of Explosives Vapour from Organic Fluorescent Sensors

Ogugu

Gillanders

Turnbull

2021

The 1st International Electronic Conference on Chemical Sensors and Analytical Chemistry

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Organic semiconductors can be used as highly sensitive fluorescent sensors for the detection of trace-level vapours of nitroaromatic explosives. This involves fluorescence quenching of the sensors and indicates the presence of explosives in the surrounding environment. However, for many organic fluorescent sensors, the quenching of fluorescence is irreversible and imposes a limitation in terms of the reusability of the sensors. Here, we present a study of thermal desorption of 2,4-DNT from thin-film explosives sensors made from the commercial fluorescent polymers Super Yellow and poly(9-vinyl carbazole). Thermal cycling of the sensor results in recovery of fluorescence, thereby making them reusable.

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Section: Introductionmentioning

confidence: 99%

Thermal Desorption of Explosives Vapour from Organic Fluorescent Sensors

Ogugu

Gillanders

Turnbull

2021

The 1st International Electronic Conference on Chemical Sensors and Analytical Chemistry

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“…Fluorescence quenching can be achieved using fluorescent small molecules [10,11], dendrimers [9,[16][17][18][19], quantum dots [20], metalorganic frameworks [21] and polymers [6][7][8]12,13]. Polymeric materials has driven this area of research because of the amplification of fluorescence quenching that occurs through the influence of one quencher within the entire multi-fluorophore polymeric chain [6,7].…”

Section: Introductionmentioning

confidence: 99%

The effect of the phenylene linkage in poly(fluorene-alt-phenylene)s on the thermodynamics and kinetics of nitroaromatic and nitroaliphatic sensing

Vamvounis

Fuhrer

Keller

et al. 2019

European Polymer Journal

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The preparation, photophysical characterization and sensing of a series of highly luminescent poly(fluorene-altphenylene)s (PFP) were studied. These PFP polymers varied the phenylene linkage in the 1,4 (PFP-p), 1,3 (PFPm) and 1,2 (PFP-o) positions. The photoluminescence of these polymers ranged from ultraviolet to blue in color in both solution and film states by simply varying the linkage of the phenylene moiety. Photon Electron Spectroscopy in Air (PESA) revealed that the change in the emission was primarily attributed to the difference of the electron affinity of the polymer. Stern-Volmer quenching studies indicated that these poly(fluorene-altphenylene) polymers are highly sensitive towards nitroaromatic materials in solution, particularly in comparison to the reference poly(9,9-di-n-hexylflourene) (PDHF). These PFP polymers were found to be four to ten times more sensitive towards dinitrobenzene as compared to PDHF. In addition, PFP-o displayed the highest polymerbased Stern-Volmer quenching towards the taggant DMNB. The solid-state fluorescence quenching of the PFP-p and PFP-m films using DMNB was enhanced (up to 71.5%) compared to the reference PDHF (59.6%) and was attributed to both thermodynamic and diffusion kinetic factors.

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“…Eventually the front reaches the interface with the substrate, causing the rate of mass uptake of the film to decrease and giving rise to the point of inflection that can be clearly seen in Figure 2b.T his behavior is in contrast to the Super Case II behavior that has been previously observed in ar ange of amorphous films comprised of conjugated dendrimers or polymers, and we propose this is aconsequence of the porous nature of 1. [5,26,27] As swelling kinetics control Case II diffusion, the front velocity for aparticular analyte-polymer system should be constant regardless of film thickness, providedt he film morphology is the same throughout the film, and this was indeed found with all the velocities being within % 10 %ofe ach other (Figure 2c).…”

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confidence: 99%

Detection of Explosive Vapors: The Roles of Exciton and Molecular Diffusion in Real‐Time Sensing

et al. 2016

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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.

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Molecular versus exciton diffusion in fluorescence-based explosive vapour sensors

Abstract: The diffusion of p-nitrotoluene vapours into polymer or dendrimer sensing films follows Super Case II dynamics in which the quenching efficiency is strongly correlated to an accelerating analyte front propagating through the neat film rather than being reliant on exciton diffusion.

Cited by 16 publications

References 29 publications

Thermal Desorption of Explosives Vapour from Organic Fluorescent Sensors

Thermal Desorption of Explosives Vapour from Organic Fluorescent Sensors

The effect of the phenylene linkage in poly(fluorene-alt-phenylene)s on the thermodynamics and kinetics of nitroaromatic and nitroaliphatic sensing

Detection of Explosive Vapors: The Roles of Exciton and Molecular Diffusion in Real‐Time Sensing

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