Search: Analytical chemistry
Abstract: Nitrogen usually consists of molecules where two atoms are strongly triple-bonded. Here, we report on an allotropic form of nitrogen where all atoms are connected with single covalent bonds, similar to carbon atoms in diamond. The compound was synthesized directly from molecular nitrogen at temperatures above 2,000 K and pressures above 110 GPa using a laser-heated diamond cellSingle-bonded cubic form of nitrogen, , Nature Materials, 8/2004, Volume 3, Issue 8, p.558 - 563, (2004)
Abstract.The structure of isomer 2 of Tb3N@C84 has been determined through single-crystal X-ray diffraction on Tb3N@C84·NiII(OEP)·2(C6H6). The carbon cage has a distinct egg shape due to the presence of a single pair of fused pentagons at one apex of the molecule. Thus, although 24 IPR structures are available to the C84 cage, Nature utilizes one of the 51 568 isomeric structures that do not conform to the IPR for this unusual molecule. The Tb3N portion of isomer 2 of Tb3N@C84 is strictly planar. One Tb atom is nestled within the fold of the fused pentagons, while the other Tb atoms are disordered over four pairs of sites.Tb3N@C84 : An Improbable, Egg-Shaped Endohedral Fullerene that Violates the Isolated Pentagon Rule, , Journal of the American Chemical Society, 09/2006, Volume 128, Issue 35, p.11352 - 11353, (2006)
The scientific and engineering principles that underlie chemical engineering can also be used to understand a wide variety of other phenomena, including in areas not thought of as being central to our profession. As such applications might be of interest to our readers, we will consider brief submissions for publication in this category as R&D notes. These submissions will undergo review, and novelty will be an important factor in reaching an editorial decision.
Abstract: The melting behavior of Ge nanocrystals embedded within SiO2 is evaluated using in situ transmission electron microscopy. The observed melting-point hysteresis is large (±17%) and nearly symmetric about the bulk melting point. This hysteresis is modeled successfully using classical nucleation theory without the need to invoke epitaxy.Large Melting-Point Hysteresis of Ge Nanocrystals Embedded in SiO2, , Physical Review Letters, Volume 97, Number 15, p.155701, (2006)