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Er4Ni is Iron carbide-like structured and crystallizes in the cubic Fd-3m space group. The structure is zero-dimensional and consists of eight Er4Ni clusters. Er is bonded in a single-bond geometry to one Ni atom. The Er–Ni bond length is 2.50 Å. Ni is bonded in a tetrahedral geometry to four equivalent Er atoms.
Tm4Ni is Iron carbide-like structured and crystallizes in the cubic Fd-3m space group. The structure is zero-dimensional and consists of eight Tm4Ni clusters. Tm is bonded in a single-bond geometry to one Ni atom. The Tm–Ni bond length is 2.49 Å. Ni is bonded in a tetrahedral geometry to four equivalent Tm atoms.
Pu4Ni is Iron carbide-like structured and crystallizes in the cubic Fd-3m space group. The structure is zero-dimensional and consists of eight Pu4Ni clusters. Pu is bonded in a single-bond geometry to one Ni atom. The Pu–Ni bond length is 2.52 Å. Ni is bonded in a tetrahedral geometry to four equivalent Pu atoms.
MgPr4 is Iron carbide-like structured and crystallizes in the cubic Fd-3m space group. The structure is zero-dimensional and consists of eight MgPr4 clusters. Mg is bonded in a tetrahedral geometry to four equivalent Pr atoms. All Mg–Pr bond lengths are 2.94 Å. Pr is bonded in a distorted single-bond geometry to one Mg atom.
MgLa4 is Iron carbide-like structured and crystallizes in the cubic Fd-3m space group. The structure is zero-dimensional and consists of eight MgLa4 clusters. Mg is bonded in a tetrahedral geometry to four equivalent La atoms. All Mg–La bond lengths are 2.99 Å. La is bonded in a distorted single-bond geometry to one Mg atom.
The single-probe heat-pulse (SPHP) technique combined with the Fiber-optic Distributed Temperature Sensing (DTS) technology can offer novel high-resolution measurements of soil moisture (θ) over spatial scales ranging from several centimeters to several kilometers. However, the key limitation of this method is in obtaining the calibration relationship between θ and soil thermal conductivity (λ) across a specific field. In a previous study, a new methodology using a Gaussian processes model was presented to account for the spatial variability in the λ-θ relationship. The model aggregated θ measurements from soil moisture sensors scattered over the SPHP transect with the corresponding DTS λ measurements at their locations. In this study, a novel methodology is tested to optimize the number and locations of soil moisture sensors required to account for the spatial variability of the λ - θ relationship to achieve higher accuracy from the SPHP technique. The proposed methodology utilizes hierarchical clustering to analyze the information contained in the spatial structure of the SPHP measurements as the soil dries from a nearly-saturated condition. The proposed methodology was tested using data from a field in Oklahoma. Monte-Carlo simulation was performed to validate the performance of the proposed methodology. The predictions obtained from the proposed methodology resulted in θ measurements accuracy comparable to those obtained from the 10% best Monte-Carlo iterations of randomly assigned soil moisture locations. Further, this study demonstrates that the proposed methodology is more efficient than the traditional practice of randomly spreading calibration soil moisture sensors along the SPHP transect.
Mechanistic understanding of large molecule conversion and the discovery of suitable heterogeneous catalysts have been lagging due to the combinatorial inventory of intermediates and the inability of humans to enumerate all structures. Here, we introduce an automated framework to predict stable configurations on transition metal surfaces and demonstrate its validity for adsorbates with up to 6 carbon and oxygen atoms on 11 metals, enabling the exploration of ~10 8 potential configurations. It combines a graph enumeration platform, force field, multi-fidelity DFT calculations, and first-principles trained machine learning. Clusters in the data reveal groups of catalysts stabilizing different structures and expose selective catalysts for showcase transformations, such as the ethylene epoxidation on Ag and Cu and the lack of C-C scission chemistry on Au. Deviations from the commonly assumed atom valency rule of small adsorbates are also manifested. This library can be leveraged to identify catalysts for converting large molecules computationally.
The 1H- and 2H-1,2,3-triazoles are isomeric five-membered ring, aromatic heterocycles that may undergo chemical equilibration by virtue of intramolecular hydrogen migration (tautomerization). Using millimeter-wave spectroscopy in the 130–375 GHz frequency range, we measured the spectroscopic constants for thirteen 1H-1,2,3-triazole and sixteen 2H-1,2,3-triazole isotopologues. Herein, we provide highly accurate and highly precise semi-experimental equilibrium (r e SE ) structures for the two tautomers based on the spectroscopic constants of each set of isotopologues, together with vibration–rotation interaction and electron-mass distribution corrections calculated using coupled-cluster singles, doubles, and perturbative triples calculations [CCSD(T)/cc-pCVTZ]. The resultant structures are compared with a “best theoretical estimate” (BTE), which has recently been shown to be in exceptional agreement with the semi-experimental equilibrium structures of other aromatic molecules. Bond distances of the 1H tautomer are determined to <0.0008 Å and bond angles to <0.2°. For the 2H tautomer, bond angles are also determined to <0.2°, but bond distances are less precise (2σ ≤ 0.0015). Finally, agreement between BTE and r e SE values is discussed.
Ge3N2 is alpha Po structured and crystallizes in the cubic Pm-3m space group. The structure is zero-dimensional and consists of one Ge3N2 cluster. Ge2+ is bonded in a bent 120 degrees geometry to two equivalent N3- atoms. Both Ge–N bond lengths are 1.87 Å. N3- is bonded in a trigonal planar geometry to three equivalent Ge2+ atoms.
InSb2 is Cyanogen Chloride-derived structured and crystallizes in the orthorhombic Pmmm space group. The structure is zero-dimensional and consists of one InSb2 cluster. In3+ is bonded in a linear geometry to two equivalent Sb+1.50- atoms. Both In–Sb bond lengths are 2.70 Å. Sb+1.50- is bonded in a single-bond geometry to one In3+ atom.
Understanding the structure and composition of aluminate complexes in extremely alkaline systems such as Bayer liquors has received enormous attentions due to its fundamental and industrial importance. However, obtaining direct molecular information of the underlying ion-ion interactions using traditional approaches such as NMR or Raman spectroscopy is challenging due to the weakness of these interactions and/or their complex overlapping spectral signatures. Here, we exploit in situ liquid secondary ion mass spectrometry (SIMS) as a new approach and show how it enables new insights. In contrast with traditional techniques, using SIMS we succeeded in acquiring information on dominant ion clusters in these alkaline systems. In Na + /K + mixed alkaline aluminate solutions we clearly observe preferential formation of Na + -anion clusters over K + -anion clusters. Further, evaluation of these clusters by density functional theory (DFT) calculations shows that these structures are stable and that their relative bond energies are consistent with their observed SIMS signal intensity differences. This demonstrates a key advantage of in situ liquid SIMS for overcoming ambiguities obscuring important information in these systems on constituent molecular clusters defined by relatively weak ion pair competition and ion-solvent interactions.
The polycrystalline Cu (In, Ga) Se2, or CIGS, based thin-film materials system has long been studied for use in photovoltaic technologies, where its bandgap tunability, mechanical flexibility, and relatively low production costs are all appealing. Nonetheless, significant defect populations, which serve to reduce efficiency, create performance instabilities, and increase concerns about long-term reliability, have hindered wide-scale adoption. Prior work, including application of a scanning probe based deep level trap spectroscopy (SP-DLTS) defect mapping technique and scanning transmission electron microscope (STEM) based electron energy loss spectroscopy (EELS), has shown that the most detrimental defects, with energy level near mid-gap (thus serving as a carrier recombination center), are most likely caused by CuIn/Ga antisites and tend to cluster at or around certain grain boundaries [1,2]. However, the exact nature of these particular boundaries — their structures, chemistries, or even the relative misorientation of their associated grains — and their relation to this defect clustering and/or its formation is yet unknown. As such, electron backscatter diffraction (EBSD) orientation mapping, directly correlated with defect-sensitive techniques like SP-DLTS and/or STEM-EELS, could prove critical for providing the final missing links toward understanding the mechanisms behind these defects. Indeed, recent studies using correlative electron beam induced current (EBIC) with EBSD have been able to identify boundaries, and their relative misorientations, that possess detrimental electronic properties [3]. However, because EBIC is unable to resolve the defect energy levels, many questions are left unanswered. Furthermore, this study, and others like it, employed focused ion beam (FIB) milling to flatten the natively-rough CIGS [3-5], which may run the risk of changing the nature of any near-surface defect structures.
CS2 is Cyanogen Chloride-derived structured and crystallizes in the orthorhombic Cmce space group. The structure is zero-dimensional and consists of four CS2 clusters. C4+ is bonded in a linear geometry to two equivalent S2- atoms. Both C–S bond lengths are 1.56 Å. S2- is bonded in a single-bond geometry to one C4+ atom.
XeF4 is Protactinium structured and crystallizes in the monoclinic P2_1/c space group. The structure is zero-dimensional and consists of two XeF4 clusters. Xe is bonded in a square co-planar geometry to four equivalent F atoms. All Xe–F bond lengths are 2.04 Å. F is bonded in a single-bond geometry to one Xe atom.
CuO crystallizes in the tetragonal I4/mmm space group. The structure is zero-dimensional and consists of two CuO clusters. Cu2+ is bonded in a bent 150 degrees geometry to two equivalent O2- atoms. Both Cu–O bond lengths are 1.74 Å. O2- is bonded in a bent 120 degrees geometry to two equivalent Cu2+ atoms.
SnS crystallizes in the orthorhombic Aem2 space group. The structure is zero-dimensional and consists of four SnS clusters. Sn2+ is bonded in a distorted single-bond geometry to one S2- atom. The Sn–S bond length is 2.58 Å. S2- is bonded in a distorted single-bond geometry to one Sn2+ atom.
XeF2XeF4 is Copper structured and crystallizes in the monoclinic P2_1/c space group. The structure is zero-dimensional and consists of two XeF2 clusters and two XeF4 clusters. In each XeF2 cluster, Xe is bonded in a linear geometry to two equivalent F atoms. Both Xe–F bond lengths are 2.08 Å. F is bonded in a single-bond geometry to one Xe atom. In each XeF4 cluster, Xe is bonded in a square co-planar geometry to four equivalent F atoms. All Xe–F bond lengths are 2.04 Å. F is bonded in a single-bond geometry to one Xe atom.
Tm4Co is Iron carbide-like structured and crystallizes in the cubic Fd-3m space group. The structure is zero-dimensional and consists of eight Tm4Co clusters. Tm is bonded in a single-bond geometry to one Co atom. The Tm–Co bond length is 2.46 Å. Co is bonded in a tetrahedral geometry to four equivalent Tm atoms.