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The magnetic adsorbent of Fe3O4@SiO2 core-shell nanoparticles modified with thiol group was synthesized for chloroauric ([AuCl4]−) adsorption. The Fe3O4 nanoparticles were prepared by co-precipitation method under mechanical stirring and coated with SiO2 by acid hydrolysis of Na2SiO3 under N2 purging. The coating of Fe3O4 nanoparticles with SiO2 prevents particles’ agglomeration by forming Fe3O4 Fe3O4 Fe3O4@SiO2 core-shell and avoids dissolution of the Fe3O4 core in the acidic medium. The coated Fe3O4 particle was modified with a thiol group using 3-mercaptopropyltrimethoxysilane via silanization reaction. The results suggest that SiO2-coated Fe3O4 particles have a size of 10–20 nm. The FTIR and EDX data indicate that the thiol groups are successfully attached to the surface of the nanoparticles. The [AuCl4]− ion adsorption by the Fe3O4@SiO2 core-shell nanoparticles followed Langmuir isotherm model with a maximum adsorption capacity of 115 mg/g and free energy (ΔG°) of 24.8 kJ/mol. The thiourea solution can be used to desorb most of the adsorbed [AuCl4]− ion. The adsorption using magnetic compounds provides easy access to the separation for both preparation and recovery.

We present a comparative study on UV matrix-assisted laser desorption (MALD), laser-induced thermal desorption (LITD), IR laser ablation, and desorption via electrical substrate heating. In order to determine to what extent the material is desorbed as individual molecules or ejected as particles, respectively, the ablated material was intercepted by a trapping plate and the particle size distribution was analyzed by atomic force microscopy (AFM). The ratio of ejected particles to free molecules is strongly dependent on the laser volatilization technique used. High energy densities in the sample, for example in UV MALD, favor molecular desorption leading to very smooth films on the trapping plate. In contrast, IR polymer ablation and LITD of micrometer thick organic films is dominated by ejection of clusters and particulates. Volatization by electrically heated flash filaments is not significantly different from substrate mediated thermal laser desorption (LD). It may allow to miniaturize and simplify mass spectrometric instrumentation for applications requiring desorption–ionization techniques.

A new type of nanocomposite particles are produced by an active plasma-metal reaction method. Co-TiN nanocomposite particle with dumbbell-like morphology shows good thermal stability. Hydrogen desorption characteristics are examined by temperature-programmed desorption experiments. Hydrogen desorption is observed at 380–600 K. The effect of CO coadsorption on the hydrogen desorption is examined and no significant effect is observed for the Co-TiN nanocomposite particle. The results are compared with those of Ni-TiN nanocomposite particle.

Ultrafine In2O3 particle layers were prepared by gas evaporation of In in atmospheres of Ar, followed by oxidation in air, and their photoconductive behavior was investigated. The mean diameter of the In2O3 particles was changed from 30 to 300 nm by changing the Ar pressure during the evaporation from 10 to 150 Torr. All the specimens showed photoconductivity associated with UV light irradiation. When the mean particle diameter decreased the photoconductive sensitivity decreased and the photocurrent decay time increased. It is concluded that the contribution of oxygen desorption and adsorption predominantly influences the photoconductivity in ultrafine In2O3 particle layers.