The assembly of colloidal nanocrystals (NCs) into superstructures with long-range translational and orientational order is sensitive to the molecular interactions between ligands bound to the NC surface. We illustrate how ligand coverage on colloidal PbS NCs can be exploited as a tunable parameter to direct the self-assembly of superlattices with predefined symmetry. We show that PbS NCs with dense ligand coverage assemble into face-centered cubic (fcc) superlattices whereas NCs with sparse ligand coverage assemble into body-centered cubic (bcc) superlattices which also exhibit orientational ordering of NCs in their lattice sites. Surface chemistry characterization combined with density functional theory calculations suggest that the loss of ligands occurs preferentially on {100} than on reconstructed {111} NC facets. The resulting anisotropic ligand distribution amplifies the role of NC shape in the assembly and leads to the formation of superlattices with translational and orientational order.

High resolution electron energy loss spectroscopy (HREELS) and temperature programmed desorption (TPD) were employed to study the decomposition of 1-epoxy-3-butene (EpB) and 2-butenal (crotonaldehyde, CrHO) on Pd(111). HREELS investigations indicate that both EpB and CrHO decompose through a common surface aldehyde intermediate that is distinct from molecular CrHO. The surface aldehyde intermediate decomposes to yield the gas phase decarbonylation products CO and propylene, as well as H2. Comparison with previous studies suggests that Pd is unique compared to previously studied surfaces in its reactivity with EpB and CrHO.

The authors have examined the effect of two molecules that form self-assembled monolayers (SAMs) on the subsequent growth of TaNx by atomic layer deposition (ALD) on two substrate surfaces, SiO2 and Cu. The SAMs that the authors have investigated include two vapor phase deposited, fluorinated alkyl silanes: Cl3Si(CH2)2(CF2)5CF3 (FOTS) and (C2H5O)3Si(CH2)2(CF2)7CF3 (HDFTEOS). Both the SAMs themselves and the TaNx thin films, grown using Ta[N(CH3)2]5 and NH3, were analyzed ex situ using contact angle, spectroscopic ellipsometry, x-ray photoelectron spectroscopy (XPS), and low energy ion-scattering spectroscopy (LEISS). First, the authors find that both SAMs on SiO2 are nominally stable at Ts ∼ 300 °C, the substrate temperature used for ALD, while on Cu, the authors find that HDFTEOS thermally desorbs, while FOTS is retained on the surface. The latter result reflects the difference in the head groups of these two molecules. The authors find that both SAMs strongly attenuate the ALD growth of TaNx on SiO2, by about a factor of 10, while on Cu, the SAMs have no effect on ALD growth. Results from LEISS and XPS are decisive in determining the nature of the mechanism of growth of TaNx on all surfaces. Growth on SiO2 is 2D and approximately layer-by-layer, while on the surfaces terminated by the SAMs, it nucleates at defect sites, is islanded, and is 3D. In the latter case, our results support growth of the TaNx thin film over the SAM, with a considerable delay in formation of a continuous thin film. Growth on Cu, with or without the SAMs, is also 3D and islanded, and there is also a delay in the formation of a continuous thin film as compared to growth on SiO2. These results highlight the power of coupling measurements from both LEISS and XPS in examinations of ultrathin films formed by ALD.

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For policymakers across the world, the importance of budget transparency is self-evident. However, most scholars mainly focus on the economic performance of budget transparency while ignoring satisfaction of the public as the recipients of this policy. Therefore, this study examines the main factors of public satisfaction with the local government budget transparency based on the theory of customer satisfaction in the context of the Chinese budget transparency policy. Data for this study were collected through an online survey involving 235 participants. Structural equation modeling (SEM) was employed to examine the proposed model. The results indicate that the budget information quality, budget information acquisition method, and public engagement are good indicators of budget transparency perceived quality, which are positively related to public satisfaction. The government image also exerts a positive effect toward public satisfaction. Furthermore, public satisfaction is also positively related to public trust toward the local government, even though the hypotheses linking public expectation to public satisfaction, and to budget transparency perceived quality are statistically insignificant. The implications of promoting budget transparency and suggestions for future work are also included in this study.