Adsorption of functionalised thiols on gold surfaces: how to build a sensitive and selective sensor for a nitroaromatic compound?

Adsorption of thiols of varying structures bearing amine, acid or aromatic functionalities was characterised by Polarisation Modulation Infrared Absorption Spectroscopy (PM-IRRAS). The so functionalised surfaces were then submitted to atmospheres containing traces of 2,4-dinitrotrifluoromethoxybenzene and gas capture was evaluated by Quartz Crystal Microbalance (QCM). The selectivity of these new sensors was also evaluated thanks to exposures to solvents: ethanol, methylethylketone, toluene and dichloromethane. The QCM response appeared to be the best one, high and specific to the nitroaromatic, for aromatic amine functions

Elaboration, activity and stability of silica-based nitroaromatic sensors

International audienceFunctionalized silica-based thin films, modified with hydrophobic groups, were synthesized and used as sensors for nitroaromatic compound (NAC) specific detection. Their performance and behavior, in terms of stability, ageing and regeneration, have been fully characterized by combining chemical characterization techniques and electron microscopy. NAC was efficiently and specifically detected using these silica-based sensors, but showed a great degradation in the presence of humidity. Moreover, the sensor sensitivity seriously decreases with storage time. Methyl- and phenyl-functionalization helped to overcome this humidity sensitivity. Surface characterization enabled us to establish a direct correlation between the appearance, and increasing amount, of adsorbed carbonyl-containing species, and sensor efficiency. This contamination, appearing after only one month, was particularly important when sensors were stored in plastic containers. Rinsing with cyclohexane enables us to recover part of the sensor performance but does not yield a complete regeneration of the sensors. This work led us to the definition of optimized elaboration and storage conditions for nitroaromatic sensor

Specificinteractions of functionalisedgoldsurfaces with ammonium perchlorate or starch; towards a chemical cartography of their mixture

International audienceBy functionalising gold samples, planar wafers or AFM tips, with an acid- or an amino acid-terminated thiols, mercaptoundecanoic acid (MUA) and homocystein (H-Cyst) respectively, we were able to differentiate the interactions with ammonium perchlorate (AP) and starch (S), two components of a nanocomposition mixture. To do so, the interaction between gold functionalized surfaces and the two targeted compounds have been characterized and quantified by several complementary techniques. Polarisation modulation-infrared spectroscopy (PM-IRRAS), and X-ray photoelectron spectroscopy (XPS), providing chemical analyses of goldsurfaces after contacting S or AP, proved that both compounds were retained on MUA or H-Cyst-modified surfaces, but to various extents. Quartz crystal microbalance on-line measurements enabled to monitor the kinetics of interaction and showed distinct differences in the behaviour of MUA and H-Cyst-surfaces towards the two compounds. Having observed that only H-Cyst-modified surfaces enables to get a contrast on the chemical force microscopy (CFM) images, this new result could be well explained by examining the data obtained by combining the above-mentioned surface characterisation techniques

Comparison of fluorescence and QCM technologies: Example of explosives detection with a pi-conjugated thin film

International audienceA pi-conjugated compound was synthesized as a sensitive material for explosives detection. The detection of vapors of 2,4-dinitrotoluene was demonstrated with quartz crystal microbalance (QCM) and fluorescence transduction methods. The fluorescence intensity monitoring shows a higher sensitivity and selectivity than the monitoring of the QCM frequency. Both methods appear to be synergic when used simultaneously as the sensor helps to discriminate interferent vapors from nitroaromatics

Detection of hydrogen peroxide using dioxazaborocanes: elucidation of the sensing mechanism at the molecular level by NMR and XPS measurements

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Development of a saw based high sensitivity anhydride hexafluorhydric acid sensor

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