ZnSe nanoparticles were synthesized by reacting vapors of (CH3)2Zn:N(C2H5)3 and H2Se, diluted in H2, in an opposed flow reactor operating at room temperature and 120 Torr. The particles were collected as random aggregates on silicon substrates and transmission electron microscopy (TEM) grids placed downstream of the reaction zone. Particle characterization using TEM and electron diffraction revealed the presence of polycrystalline nanoparticles with diameter of about 40 nm that were apparently formed from coagulation of smaller nanocrystals with characteristic size of about 4 nm. Raman spectra of the nanoparticles revealed an asymmetrically broadened feature associated with the LO phonon of ZnSe, indicating the presence of smaller single-crystalline grains.

NaX zeolite was ion-exchanged to obtain LiX and AgX zeolites. The LiX form was further exchanged to replace 20% of the Li+ cations by Ag+, to obtain a LiAgX zeolite. Equilibrium adsorption isotherms of pure-component N2 and O2 were measured at 25 and 50 °C on these four zeolites. AgX was stable since the N2 isotherm was not affected after prolonged exposure of the zeolite to air at 350 °C. Bonding of N2 was substantially stronger on AgX than on the other zeolites. The high isosteric heat of adsorption (8.4 kcal/mol) and the relatively slow desorption of N2 on AgX indicated some degree of weak π-complexation, which was substantiated by molecular orbital calculation results using model systems. Binary N2/O2 selectivity (or separation factor, α) was calculated by using the ideal adsorbed solution theory. The high N2/O2 selectivities at low total pressures for AgX will result in difficult N2 desorption; therefore, AgX is not suitable for air separation. LiX is presently employed in industry as the sorbent for air separation by pressure-swing adsorption. Comparing LiX with LiAgX, the N2/O2 selectivities were higher for LiAgX at high total pressures and lower for LiAgX at lower pressures, due to a (relative) selectivity reversal. This result, combined with the higher N2 capacity for LiAgX, led to the conclusion that LiAgX can be superior to LiX for air separation.

The epitaxial growth of the diluted magnetic semiconductor (DMS) Zn1−xFexSe (0<x≤0.22) by metalorganic vapor phase epitaxy (MOVPE) is reported. The films were grown on (100) GaAs substrates in a vertical stagnation flow reactor with a specially designed inlet to minimize prereactions between the groups II and VI precursors. The precursors used in this study were (CH3)2Zn:N(CH2H5)3, Fe(CO)5, and H2Se diluted in H2 carrier gas. The epilayers were characterized by x-ray diffraction (XRD), Raman, absorption, and x-ray photoelectron spectroscopies (XPS). Typical growth rates were from 3–4 μm/h, which are significantly higher than those obtained by molecular beam epitaxy. Thus, in addition to the growth of DMS multilayer structures, MOVPE appears to be very promising for efficient growth of thick DMS films for Faraday magneto-optical applications.

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