GAS-PHASE MOLECULAR ALLOYS OF BULK IMMISCIBLE ELEMENTS - FEXAGY

Binary cluster ions of iron and silver are produced by pulsed supersonic nozzle expansion, pulsed laser ionization. Although these elements are mutually insoluble in both the liquid and solid states, all combinations of FexAgy+ are detected by time-of-flight mass spectrometry. In the low-nuclearity duster regime, species having the same number of atoms but different Fe:Ag ratios are not observed in equal abundance. High-ionizing laser fluences produce clusters richer in silver. The FeAg+ dimer is explored. Its binding energy is bracketed between 2.33 and 3.50 eV. Local spin density calculations give qualitative insight into the strength of the cationic dimer bond as contrasted with that of neutral FeAg. The ionization potential of the latter is predicted to be 3.78 eV. Some comparisons are made concerning the phase diagram of Fe-Ag in cluster- and bulk-size regimes, the properties of dilute and concentrated clusters of magnetic atoms in a diamagnetic silver host, and surface magnetism connected with iron overlayers on silver or monolayer sandwiches of iron between silver.