The synthesis of ultra-long high-quality zinc sulfide (ZnS) nanowires of uniform size on heterogeneous substrates is highly desirable for investigating the fundamental properties of ZnS nanowires and for fabricating integrated functional nanodevices. The present study developed a novel technique for growing ultra-long ZnS nanowires on thin-catalyst-coated substrates. ZnS nanowires were synthesized by chemical vapor deposition on a silicon substrate deposited by gold (* 5 nm in thickness) as the catalyst at 550, 600, 700, 750 and 800°C. The structural properties of the samples were investigated by X-ray diffraction, and the results showed that the fabricated nanowires have both wurtzite and zinc blend structures. The morphological properties of the nanowires were determined by scanning electron microscopy, and the results show that the substrate is thoroughly coated with 10 lm of zinc sulfide nanowires. Increasing the substrate temperature from 600 to 800°C increased the diameter of the nanowires and decreased the length. The growth mechanism of the nanowires was vapor-liquid-solid. The EDX spectra of this sample showed an absence of contamination, confirming the high purity of the ZnS nanowires.

Negative polarity atmospheric pressure chemical ionization of selected chlorinated hydrocarbons (tetrachloromethane CCl4 and hexachloroethane C2Cl6, dichloromethane CH2Cl2, trichloromethane CHCl3, 1,1,1,2-tetrachloroethane 1,1,1,2-C2H2Cl4, 1,1,2,2-tetrachloroethane 1,1,2,2,-C2H2Cl4 1,1,2-trichloroethane 1,1,2-C2H3Cl3, and 1,1,2-trichloroethane 1,1,2-C2HCl3) was studied using ion mobility spectrometry (IMS) and IMS combined with time-of-flight mass spectrometer (IMS-TOF MS) techniques, in the dry air and at two different drift gas temperatures (323 and 373 K). The ionization was performed using the O2 –CO2(H2O)0,1 reactant ions (RIs), and the dominant ionization reaction was the dissociative electron transfer. The ionization resulted in the appearance of Cl– ions for all substances and [O2H..Cl]− ions, which were absent in the case of perchlorinated substances. The quantum-chemical calculations at the density functional theory level of theory using the ωB97X-D/aug-cc-pVTZ method were performed to calculate the thermochemical data (heats of formations, electron affinities, reaction enthalpies) for RIs, neutral substances, neutral fragments, and the anionic fragments. The calculations supported the experimental observations regarding the endothermicity of the Cl– channel for all substances and the exothermicity of the [O2H..Cl]− channel for the tetrachloro- and trichloroethanes.

Rationale Phthalates are widely used in consumer products in the chemical industries. Due to their abundance in the milieu, their potentially harmful effect on the environment, human and animal health there is a need for sensitive and fast methods for their detection. Methods Positive polarity Corona Discharge Atmospheric Pressure Chemical Ionization (CD‐APCI) in the air was applied for ionization of phthalates. The ionization method for the phthalates was studied by atmospheric pressure Ion Mobility Spectrometry (IMS) and hybrid IMS/orthogonal acceleration Time‐of‐Flight Mass spectrometry (IMS‐oaTOF‐MS). Results CD‐APCI IMS and MS spectra of selected phthalates (dimethyl phthalate, diethyl phthalate, diethyl isophthalate, diethyl terephthalate, dipropyl phthalate, diisopropyl phthalate, dibutyl phthalate, diisobutyl phthalate, and dibutyl terephthalate) were recorded. In the case of the ortho‐ and “iso”‐isomers exclusively the protonated molecular ions [M + H]+ were detected. In the case of the para‐ and meta‐isomers and regioisomers, APCI resulted in the appearance of hydrated protonated molecular ions [M + H]+·(H2O)0,1,2. The ion mobilities, collision cross‐sections of these ions in air, as well as the limits of detection (LODs) for the phthalate vapors, were determined. In the case of isomeric phthalates, we have demonstrated the potential of the IMS technique for their separation. Conclusions The results show that CD‐APCI in combination with IMS and IMS‐oaTOF‐MS is a suitable method for the fast and sensitive detection of phthalates with the potential to separate some isomers.

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Atmospheric Pressure Field Effect (APFE) ionisation source for drift tube Ion Mobility Spectrometry has been developed for operation in positive and negative polarities. The formation of the negative and positive...