A simple procedure has been developed to prepare thiol-derivatized nanoparticles of metals. The procedure involves the transfer of well-characterized metal hydrosols to a hydrocarbon medium containing the thiol. Thiol-derivatized nanoparticles Au, Ag, and Pt of near spherical shape forming nanocrystalline arrays have been characterized by X-ray diffraction, transmission electron microscopy (TEM), and other techniques. Thiolderivatized Au particles of mean diameters of 1.0, 2.1, and 4.2 nm from nanocrystalline arrays show characteristic X-ray diffraction patterns. The nanoparticles exhibit Moiré fringes when deposited on a flake of MoSe 2 , showing that each particle is in itself crystalline. Besides spherical nanoparticles, thiol-derivatized particles of other shapes have been prepared, hexagonal Pt nanoparticles being particularly novel. Scanning tunneling microscopy images not only confirm the size and shape of nanoparticles revealed by TEM, but also show evidence for thiol molecules on the surface.

No abstract

Molecular beams generated from the vapors above the surfaces of alcohol-water mixtures have been examined by mass spectrometry. The alcohols examined are methanol, ethanol, n-propanol, and n-butanol. The variation of the vapor-phase mole fraction of the alcohol, estimated from the cluster populations in the molecular beam, with the liquid mole fraction is found to be identical to that of the surface concentration of the alcohol in the liquid obtained from surface-tension measurements. The populations of the neat alcohol clusters, as distinct from those of alcohol-water clusters, also exhibit a comparable trend. Surface enrichment is considerably more pronounced in the case of n-butanol and n-propanol compared to that of ethanol.

No abstract

No abstract