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People of Nia is a cultural commencement designed to honor and embrace Black students who have successfully completed their college degrees at a predominantly White college or university. This article discusses this unique campus celebration, presents the history of People of Nia, and describes how People of Nia is presented on one predominantly White research university campus. (Author/EV)

Reactions of N[sub 2] with Ni[sub n]Al clusters, n = 14-19, are used to determine the location of the A1 atom within the cluster framework. N[sub 2] saturation levels are consistent with cluster structures in which one surface atom of the corresponding Ni[sub n] +1 cluster is replaced with an A1 atom. For n = 14 and 17-19 it is possible to precisely locate the A1 atom within the surface. In general, its placement maximizes the number of Ni-A1 bonds for a surface A1 atom. [ABSTRACT FROM AUTHOR]

The structures of Ni[sub n]A1[sub p] clusters of all compositions with n + p = 12, 13, and 14 are studied both experimentally and theoretically. Experimental reactions of the clusters with N[sub 2] are used to determine the number of Ni atoms residing in the cluster surfaces. In agreement with the theoretical predictions, the N[sub 2] saturation levels are consistent with clusters having icosahedral and icosahedral-based structures. The various N[sub 2] adsorption channels seen in the experiment are explained in terms of the computed composition-dependent patterns of the configurational energies of the different structural forms. [ABSTRACT FROM AUTHOR]

Two-reagent reactions of Ni[sub 19] and Ni[sub 23] with hydrogen/deuterium and ammonia are studied to probe adsorbate-induced cluster structural changes. H/D and NH[sub 3] bind to the clusters noncompetitively, i.e., to different sites, so simultaneous saturation by the two reagents can be achieved. It is found that H/D adsorption causes a change in Ni[sub 19] from the double icosahedral structure to a face-centered cubic (fcc) or hexagonal close-packed (hcp) one, but that subsequent saturation with NH[sub 3] converts the cluster back to the double icosahedron. No such structural changes are seen for the triple icosahedral Ni[sub 23]. The results for Ni[sub 19] are interpreted in terms of the electron withdrawing or donating character of the ligands and the consequent effect on the extent of d-orbital bonding in the cluster. Possible configurations of the H/D atom binding sites on the icosahedral Ni[sub 19] and Ni[sub 23] clusters and on the fcc/hcp Ni[sub 19] cluster are presented. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Manganese clusters are formed by laser vaporization in an inert gas condensation source cooled to -160 °C. A pure manganese target is used as well as a manganese target containing 2 mol % carbon. The clusters are reacted with hydrogen both in the region of cluster growth and in a flow-tube reactor (FTR) downstream of the cluster source. The reactions, both with hydrogen atoms in the cluster growth region and dissociative chemisorption of H2 in the FTR, result in hydrogen atoms bound to the clusters, except that for Mn15 and smaller clusters the H atoms are unstable against H2 desorption. Above Mn15 stable hydrides are formed, but the rate of reaction in the FTR varies considerably with cluster size. This abrupt change in the ability to bind hydrogen may reflect a significant change in the character of the bonding within the cluster, perhaps from van der Waals to metallic. MnnC clusters readily react with hydrogen for n>=6 to form MnnCH2. Further reactivity generally follows the pattern of the bare clusters, suggesting that the two hydrogen atoms on MnnCH2 are bound to the carbon. Under certain conditions a large intensity of MnnCH3 species (n≥1) is seen. From these results and earlier reports of reactions of Mn with various hydrocarbons, an energy of 1.21±0.09 eV is determined for the Mn–CH3 bond. © 1996 American Institute of Physics. [ABSTRACT FROM AUTHOR]

The molecular adsorption of nitrogen on nickel clusters is used to probe the clusters’ geometrical structures. The application of nitrogen binding rules derived from earlier studies of both larger and smaller nickel clusters allows a determination of structure from nitrogen uptake patterns. In the 16- and 28-atom size region cluster structure is dominated by local pentagonal symmetry, a consequence of a preference for close packing of atoms on clusters with curved surfaces. In most cases, the structures that result can be derived from the 13-atom icosahedron, the polyicosahedral 19-, 23-, and 26-atom clusters, and the 55-atom icosahedron, by adding or removing atoms. Icosahedral and polyicosahedral clusters often have substantial surface strain, which in some cases is relieved by deviations from the ideal geometry. Structures are proposed for all clusters in the Ni16 to Ni28 size range, with the exception of Ni27. Generally, there is no evidence for structural changes as a consequence of nitrogen binding, so that the proposed structures are those of the bare as well as the nitrogenated clusters. Where possible, comparison with existing theoretical calculations of nickel cluster structure is made. © 1995 American Institute of Physics. [ABSTRACT FROM AUTHOR]

The geometrical structure of small nickel clusters is probed via molecular adsorption of nitrogen on their surfaces. Nitrogen uptake patterns can be rationalized with the proposed structures if it is assumed that N2 binds to every exposed nickel atom, that the binding energies decrease with increasing metal—metal coordination, and that atoms that are four or less coordinate can bind two nitrogen molecules. In some cases nitrogen adsorption causes a change in cluster structure, usually to one that can accommodate more nitrogen molecules. Cluster structures are proposed for all clusters (bare and nitrogenated) in the 3–15-atom size range except Ni4 and Ni11. The nitrogen uptake for Ni4 is consistent with virtually any structure, and the data for Ni11 could not be interpreted in terms of a specific structure. In general, nickel cluster structures are different from those found for rare gas clusters as well as those derived from bulk packing. A comparison of the experimental results with existing theoretical calculations is presented. [ABSTRACT FROM AUTHOR]

Reactions of cobalt clusters in the 6 to 150 atom size range with water and ammonia are used to probe cluster geometrical structure. Clusters saturated with ammonia are found in several isomeric forms in much of this size region, including a structure based on icosahedral packing for clusters having 50 to 120 atoms. The variations with cluster size of the binding energy for a single water molecule provide evidence for icosahedral structure of the bare cobalt clusters in the same size range seen for the ammoniated clusters. However, both probes suggest that in many cases the bare clusters also have multiple isomers. The evidence for icosahedral structure in the bare and ammoniated clusters disappears above ∼120 atoms and is clearly not seen at the third icosahedral shell closing at 147 atoms. Comparison with earlier studies of hydrogenated cobalt clusters and with bare and hydrogenated nickel clusters is made. Reasons for the failure to form the closed-shell 147 atom icosahedral cluster are discussed. [ABSTRACT FROM AUTHOR]