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Title: Vapor phase nucleation of the short-chain n -alkanes ( n -pentane, n -hexane and n -heptane): Experiments and Monte Carlo simulations
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Publication Date:
Journal Name:
The Journal of Chemical Physics
Page Range or eLocation-ID:
American Institute of Physics
Sponsoring Org:
National Science Foundation
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  1. Abstract

    We describe convenient preparations ofN,N′‐dialkyl‐1,3‐propanedialdiminium chlorides,N,N′‐dialkyl‐1,3‐propanedialdimines, and lithiumN,N′‐dialkyl‐1,3‐propanedialdiminates in which the alkyl groups are methyl, ethyl, isopropyl, ortert‐butyl. For the dialdiminium salts, the N2C3backbone is always in thetrans‐s‐transconfiguration. Three isomers are present in solution except for thetert‐butyl compound, for which only two isomers are present; increasing the steric bulk of theN‐alkyl substituents shifts the equilibrium away from the (Z,Z) isomer in favor of the (E,Z), and (E,E) isomers. For the neutral dialdimines, crystal structures show that the methyl and isopropyl compounds adopt the (E,Z) form, whereas thetert‐butyl compound is in the (E,E) form. In aprotic solvents all four dialdimines (as well as the lithium dialdiminate salts) adoptcis‐s‐cisconformations in which there presumably is either an intramolecular hydrogen bond (or a lithium cation) between the two nitrogen atoms.

  2. Abstract

    The Ag and In co‐doped PbTe, AgnPb100InnTe100+2n(LIST), exhibitsn‐type behavior and features unique inherent electronic levels that induce self‐tuning carrier density. Results show that In is amphoteric in the LIST, forming both In3+and In1+centers. Through unique interplay of valence fluctuations in the In centers and conduction band filling, the electron carrier density can be increased from ≈3.1 × 1018cm−3at 323 K to ≈2.4 × 1019cm−3at 820 K, leading to large power factors peaking at ≈16.0 µWcm−1K−2at 873 K. The lone pair of electrons from In+can be thermally continuously promoted into the conduction band forming In3+, consistent with the amphoteric character of In. Moreover, with rising temperature, the Fermi level shifts into the conduction band, which enlarges the optical band gap based on the Moss–Burstein effect, and reduces bipolar diffusion and thermal conductivity. Adding extra Ag in LIST improves the electrical transport properties and meanwhile lowers the lattice thermal conductivity to ≈0.40 Wm−1K−1. The addition of Ag creates spindle‐shaped Ag2Te nanoprecipitates and atomic‐scale interstitials that scatter a broader set of phonons. As a result, a maximumZTvalue ≈1.5 at 873 K is achieved in Ag6Pb100InTe102(LIST).