The sputtering of Si by 3-keV Ar+ ions under simultaneous exposure to a beam of XeF2 gas has been investigated. The masses and some energy distributions of the neutral particles emitted from the target have been determined by mass spectrometry and time of flight. We found the following Si-containing ions: Si+, SiF+, SiF+2, and SiF+3. The energy distributions of the sputtered particles cannot be explained by thermal desorption at the target temperature but can be interpreted as a collision cascadelike mechanism with a low surface binding energy.

Si sputtering yields and Si to SiO2 etch rate ratios have been determined by measuring the depth of the etched craters after Ar+ ion bombardment. The experiments have been performed with energies down to 50 eV both with and without Cl2. Surprisingly high Si sputtering yields are obtained in a Cl2 environment by low-energy Ar+ ions. Hence, the influence of Cl2 on the Si sputtering mechanism is much larger for low ion energies than for high ion energies. Whereas the Si sputtering yield is enhanced by the presence of Cl2, the SiO2 sputtering yield is hardly affected. Therefore, large differences in the etch rate (high selectivities) between Si and SiO2 are obtained at low ion energies.

Sputtering of Si in a Cl2 environment by Ar+ and Xe+ ions with energies down to 75 eV has been investigated. Mass spectra and time-of-flight distributions of the sputtered species have been measured. Under 75-eV Ar+-ion bombardment of the Si target, SiCl, SiCl2, SiCl3, and/or SiCl4 are sputtered. When increasing the ion energy the SiCl4 contribution decreases in comparison with SiCl. This is caused by the fact that the newly formed Si-Cl compounds are sputtered at a high rate compared to the rate of SiCl4 formation. Time-of-flight distributions indicate that under 100-eV Ar+-ion bombardment the species are not sputtered by a collision-cascade mechanism. The spectra can be fitted by Maxwell–Boltzmann distributions at a high (>2000 K) temperature. Increasing the Ar+-ion energy to approximately 250 eV the time-of-flight spectra of the sputtered species change from Maxwell–Boltzmann-like into spectra as expected for a collision-cascade mechanism. For low-energy Xe+ ion bombardment the sputtered species also show Maxwell–Boltzmann time-of-flight distributions. The change from Maxwell–Boltzmann to collision-cascade distributions occurs at higher ion energies than for Ar+-ion bombardment. The results obtained for low ion energies are discussed in terms of evaporation from an ion-induced hot spot.

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Starting from the enantiomerically pure and racemic chiral Lewis bases 1-phenylethylamine and 1-(1-naphthyl)ethylamine inert cobalt(III) complexes of the general composition Co(Hdmg) 2 (lig)X (Hdmg ϭ dimethylglyoximate; lig ϭ Lewis base; X ϭ CN, NCO, NO 2 ) were synthesized and characterized by single crystal X-ray diffraction. The enantiopure complexes were used as building blocks for the synthesis of binary crystals. Solid solutions resulted from cocrystallizing isomorphous compounds of equal chirality whereas complexes of opposite chirality formed well-ordered heterochiral solids with efficient packing. Two binary crystals of