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In order to sensitively, selectively, and rapidly detect the constituents relevant to improvised explosive devices (IEDs), the sensing properties of ZnS nanocrystals (NCs) are regulated by tailoring the doping level of Mn2+. The responses of the sensors fabricated by ZnS NCs with different Mn-doping levels (Mn:ZnS) toward the constituents, such as sulphur powder and black powder, generally increases first and then decreases with the increase of the concentration of doped Mn2+, and reaches the climate with an atomic ratio of 2.23% at room temperature. The sensory array based on eight sensors of Mn:ZnS NCs can realize the detection of two typical military explosives and six constituents relevant to IEDs within 7 s and can recover in 19 s. Furthermore, the fingerprinting of the constituents is achieved by pattern recognizing the inherent kinetics and thermodynamics of interaction between the sensory array and the constituents. Thus, a simple chemiresistive sensing strategy based on semiconductor NCs which can rapidly, supersensitively, and discriminatively detect the constituents relevant to IEDs is explored for the first time. [ABSTRACT FROM AUTHOR]

A high-performance Schottky sensor boosted by interface modulation is fabricated for the detection of trace nitro-explosives vapors. The interface modulation strategy results in a silicon nanowires (SiNWs) array/TiO2/reduced graphene oxide (rGO) sensor with sensitive and selective response toward nitro-explosives vapors. The response of the SiNWs array/TiO2/rGO sensor toward nitro-explosives vapors, such as 9 ppb 2,4,6-trinitrotoluene, 4.9 ppt hexogen, and 0.25 ppq octagon, is boosted by 2.4, 7.5, and 5 times with the insertion of TiO2. Superior selectivity is shown even compared with interfering gases of 10 ppm. Such good sensing performance can be attributed to the good sensing performance of the Schottky heterojunction-based sensor, the Schottky barrier height modulation with the insertion of TiO2, SiNWs array structure enhanced diffusion, and TiO2 nanoparticles enhanced adsorption. This is believed to be the first Schottky heterojunction-based sensor for nitro-explosives vapors detection. This work would open a new way to develop highly sensitive and selective sensors. [ABSTRACT FROM AUTHOR]

Silicon wafers covered with a thermally grown high-quality SiO2 layer were often used as the substrate to house different nanostructures to fabricate photodetection devices. No reports have ever challenged directly fabricating photodetectors utilizing leakage current through non-high-quality SiO2 films and the intrinsic light absorption properties of Si. Herein, we show that metal/SiO2/Si planar photodetectors could be easily fabricated by simply depositing two metal electrodes (such as, Au, Ag and Al) on top of SiO2/Si wafer in which the SiO2 layer is of non-high quality. The responsivity, stability, photoresponse characteristics and light intensity sensitivity are systematically evaluated. Our results clearly show that the present conveniently and cost-effectively fabricated metal/SiO2/Si planar photodetectors are of great advantage as compared to many of the nanostructure-based photodetectors constructed on SiO2/Si substrate. [ABSTRACT FROM AUTHOR]

The specific fluorescent detection of α-methyltryptamine (AMT) presents a great challenge because similar amine groups and benzene rings exist in a variety of amines. Here, we show the precise modulation of the electron-withdrawing strength of the π-conjugate bridge in aldehyde-containing Schiff base-based fluorescent probes for ultratrace AMT discrimination. It is found that different electron-withdrawing groups -C 6 H 4 , -C 6 H 2 N 2 , and -C 6 H 2 Br 2 as the π-conjugate bridge of the 2-dicyanomethylidene-3-cyano-4,5,5-trimethyl-2,5-dihydrofuran (TCF)-based probes can classify and identify organic amines with different amine nucleophilicities. Notably, the probe with -C 6 H 2 Br 2 as the π-conjugate bridge, denoted as BrFS-TCF, which has the highest electrophilicity of the recognition site, shows a superior nM-level limit of detection (LOD) and an instant response time (<0.1 s) toward AMT. Especially, it shows an excellent selectivity facing the secondary amines, tertiary amines, aromatic amines, and even primary amines. The present strategy would provide a new pathway for chemical substances with similar structures and properties and especially for fighting against illegal drugs.

The exploration of the intrinsic relationship between the phototautomerization and photoelectric properties is of great significance for the application of the emerging novel organic materials, such as the (bi)heterocyclic thiazolo[5,4- d ]thiazole derivatives (TzTz). Here, by introducing the chemical-controlling protonation, a barrierless spontaneous rotation movement of the designed TzTz derivative (2,5-diyl-amino-thiazolo[5,4- d ]thiazole, DA-TzTz) was ensured through the facilitation of the excited-state intramolecular proton transfer (ESIPT) triggered twisted intramolecular charge transfer (TICT) process by the enhancement of the intramolecular hydrogen bonds, steric hindrance effect, and conjugative effect. It is further verified that the hetero S atoms could mostly effect the proton accepting ability of -N═ through comparing with the influences to the intramolecular H-bond between the protonated/nonprotonated amino groups and the -N═ atoms brought by the replacement of them with N or O atoms. As a result, the dissociation and rearrangement of the π conjugation in DA-TzTz accompanying with the variation of the optoelectronic characteristics was benefited from the establishment of the preferential charge-transfer and separation. We expect this tentative study could establish a new concept of designing an efficient charge-transfer and separation method, paving the way for the development of the TzTz derivatives and other optoelectronic organic materials.