We have carried out a comprehensive survey of the isotopic compositions (H, B, C, N, O, S) of a suite of interplanetary dust particles (IDPs), including both cluster and individual particles. Isotopic imaging with the NanoSIMS shows the presence of numerous discrete hotspots that are strongly enriched in 15 Based on their N isotopic compositions, the IDPs studied here can be divided into two groups. One group is characterized as being "isotopically primitive" and consists of those IDPs that have anomalous bulk N isotopic compositions. These particles typically also contain numerous 15 N-rich hotspots, occasional C isotopic anomalies, and abundant presolar silicate grains. In contrast, the other "isotopically normal" IDPs have normal bulk N isotopic compositions and, although some contain 15 N-rich hotspots, none exhibit C isotopic anomalies and none contain presolar silicate or oxide grains. Thus, isotopically interesting IDPs can be identified and selected on the basis of their N isotopic compositions for further study. However, isotopes. This may be due to different effects of secondary processing on the isotopic systems involved.3

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We show that under certain conditions, highly Co-enriched TiO2 anatase clusters nucleate on epitaxial TiO2 anatase grown on LaAlO3(001) by oxygen plasma assisted molecular beam epitaxy. In the most extreme cases, virtually all incident Co segregates to the clusters, yielding a nanoscale ferromagnetic phase that is not ferromagnetic in homogeneous films of the same Co concentration. The nucleation of this phase simultaneous with continuous epitaxial film growth must be carefully monitored in order to avoid drawing false conclusions about the film structure.