The similarity between the laborato ry spectra of Ti14C13 and the stellar spectra was striking, but it also posed a problem: Low-mass stars don't contain much titanium, yet high densities of this metal would have to be blown off from the star to account for the TiC grain siz es observed in graphite Stardust. The atoms on each edge—a 27-atom frag researchers conclude that the event cre ating TiC deposits must involve a rather ment of bulk titanium carbide (TiC). The IR spectra of Ti14C13 and some substantial loss of stellar mass over the larger clusters were found to have a course of a century or so—that is, a prominent peak at 20.1 μιη. That finding more catastrophic end than has general might have ended up in the literature ly been thought to occur. Further studies of metal carbides in unappreciated if Tielens and a colleague had not visited the FOM Institute last the lab and in stars are under way. For October to discuss another research Duncan, it's been an exhilarating inter project of Meijer's. The visitors walked disciplinary journey—"the most impor by a poster showing the FELIX spectra tant thing in chemistry I have ever been thus joins a roster of some 120 small or of titanium carbide clusters. "That's associated with," he tells C&EN. Ron Dagani ganic and inorganic molecules that have when their jaws dropped," Duncan says. been identified in the vicinity of stars or in interstellar gas and dust clouds. Scientists have suggested several sub Editor Named For New ACS Journal Nano Letters stances that might account for the 20.1μιη feature, including silicon disulfide A. Paul Alivisatos, professor of chemis try professor. He was promoted to asso (SiS2), nanodiamonds, urea, and hydro- try and of materials science and mineral ciate professor in 1993 and to professor genated fullerenes. However, none of engineering at the University of Califor two years later. Alivisatos was appointed these has proved compelling. And "in my nia, Berkeley, has been appointed edi Chancellor's Professor for 1998-2001. opinion," says astronomer Sun Kwok of tor of the American Chemical Society's He is also a principal investigator in the the University of Calgary in Canada, "the new journal Nano Letters. ACS will be Materials Sciences Division at Law titanium carbide identification is proba gin publishing the journal next January rence Berkeley National Laboratory. In his research, Alivisatos concentrates bly the best among all the proposals." (C&EN, Dec. 13,1999, page 9). on the physical chemistry Tielens is "quite confident" in the Nano Letters will offer of semiconductor nanocidentification, especially since titanium readers preliminary re rystals, and in particular, carbide grains embedded in microme search results through their structural, optical, ter-sized graphite grains have previous rapid communication of electrical, and thermody ly been found in meteorites and isotopic short papers. The journal namic properties. Alivisa analysis pointed to low-mass stars as the will initially be published tos says these properties source of these grains. But no one previ monthly and later will ap "vary remarkably" with ously had provided such direct astro pear on a twice-monthly the size of the crystals nomical evidence for the origin of titani basis. Topics will include and are dominated by um carbide in low-mass stars. physical, chemical, and quantum effects. He biological phenomena; Such a demonstration certainly was notes that "these crystal not on Duncan's mind when in 1998 he processes; and applica lites represent a limit to forged a collaboration with chemical tions for materials and de the miniaturization of the physicist Gerard Meijer and his col vices in the nanoscale size features in electronic range. As this scope indi leagues at the FOM (Foundation for Fun circuits." damental Research on Matter) Institute cates, Nano Letters is in Alivisatos for Plasma Physics "Rijnhuizen" in Nieu- tended to draw together Alivisatos' honors in wegein, the Netherlands. Duncan wanted readers and authors from a multitude of clude the National Science Foundation's to use the institute's Free-Electron Laser nano-relatedfieldswho haven't previous Presidential Young Investigator Award for Infrared Experiments (FELIX) to ly shared a common forum. and the Materials Research Society's study gas-phase metal clusters. Alivisatos, who was born in Chicago in Outstanding Young Investigator Award. Meijer's coworkers Gert von Helden 1959, spent many of his teen years in He has been a member of the Defense and Deniz van Heijnsbergen oversaw the Greece. He returned to his hometown for Science Study Group and served on panels construction of a molecular beam machine a B A degree in chemistry at the Univer of the Defense Science Board. Alivisatos like the one Duncan had been using to pre sity of Chicago. He earned a Ph.D. in has been on the editorial boards of the pare metal clusters in Georgia and mated it physical chemistry at UC Berkeley in Journal of Physical Chemistry, Chemical with thefree-electronlaser. This allowed 1986 and spent the next two years as a Physics, the Journal of Chemical Physics, and Advanced Materials. He has been a them to obtain the gas-phase spectra of in postdoctoral fellow at AT&T Bell Labs. dividual mass-selected clusters such as He then began his UC Berkeley scientific editor oiPhysChemComm. Ti14C13. This cluster is a cube with three teaching career as an assistant chemis Sophie Wilkinson The dying star In the heart of the Egg Nebula expels Jets of gas and dust and shows a strong spectral peak at 20.1 μπι (top trace) that has been matched to a similar feature (bottom) observed In laboratory IR spectra of gas-phase titanium carbide clusters, a few of which are shown dancing around the nebula.
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