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This paper provides the fifth manifestation of a new tradition by which the editors of Comments on Inorganic Chemistry wish to lead by example, whereby we start publishing original research content that, nonetheless, preserves the Journal's identity as a niche for critical discussion of contemporary literature in inorganic chemistry (For the previous manifestations, see: Comments Inorg. Chem. 2018, 38, 1–35; 2019, 39, 1–26; 2019, 39, 188–215; 2020, 40, 1–24.) Herein, synthetic details, solid-state structures, and photophysical properties of a group of silver(I) and copper(I) complexes are described. Two silver-based coordination polymers have been obtained: {[3,5-(CF3)2Pz]2(bpp)Ag2}∞ (1) and {[3,5-(CF3)2Pz][5-(C6F5)Ttz](bpp)Ag}∞ (2) – constructed from bent 1,3-bis(4-pyridyl)propane (bpp), 3,5-bis(trifluoromethyl)pyrazole ([3,5-(CF3)2Pz]H) and 5-pentafluorophenyl-tetrazole ([5-(C6F5)Ttz]H) in order to inspect the influence of mixed ligands on the resulting silver-based coordination complexes. The structure of 1 shows a distorted trigonal planar geometry with both the bpp and [3,5-(CF3)2Pz] ligands binding to the silver atom. The silver in 2 shows an uncommon interaction with the three different ligands. Also, two different geometries including distorted tetrahedral and distorted trigonal were presented for two different silver atoms. An interesting result was obtained for the Cu(I) coordination polymer {[Cu(bpp)2][BF4]}∞ (3) which was successfully synthesized in a solventless reaction but not a solvent-mediated reaction, hence manifesting a "green" chemistry route. The structure of 3 shows an ideal tetrahedral geometry similar to that for the silver analogue, {[Ag(bpp)2][BF4]}∞ (3a), published previously, whereas herein we obtained the same product with the same crystal structure via a more facile conventional synthetic route. All four complexes show bpp ligand-centered green emissions at ambient and cryogenic temperatures. Finally, a commentary is added to contrast the solventless vs solvent-mediated reactions in both this investigation and a precedent thereof by the same corresponding author's group (Inorg. Chem. 2018, 57, 9962–9976), whereby reactions proceeded successfully only via the solventless route through mechanical grinding herein and spontaneous sublimation by vapor diffusion from the solid-state of one reactant to another yet nonvolatile reactant in the literature precedent, respectively. [ABSTRACT FROM AUTHOR]

This study aimed to understand the impacts of latent energy as well as snow fall speeds on precipitation properties and synoptic‐scale storm characteristics of a wintertime midlatitude cyclone. Simulations of a potent winter storm that impacted the Rocky Mountains and northern Great Plains of the United States in February 2017 were performed using the Weather Research and Forecasting model with latent heating or cooling from individual microphysical processes systematically turned off and fall speeds adjusted by ±50%. Results indicated substantial impacts on the microphysical characteristics of the simulated storm to fall speed, cooling from sublimation, and warming from deposition. The impacts of cooling and warming were manifested as differences in accumulated snowfall. Increased (decreased) fall speeds led to smaller (larger) ice crystals and total mass, resulting in offsetting effects on the precipitation flux, and thus minimal impacts on snowfall and large‐scale characteristics of the storm. Warming and cooling associated with deposition and sublimation, respectively, impacted the synoptic‐scale dynamics, whereby removing warming from deposition resulted in an increased meridional temperature gradient near the jet stream, thus increasing the jet strength and causing it to be more westerly with less curvature aloft. This in turn limited upper‐level divergence, creating a weaker surface low and shifting the precipitation shield southward. The opposite occurred with the removal of latent cooling due to sublimation. This study highlights the potential importance of latent energy associated with ice sublimation and deposition and fall speeds in the larger‐scale characteristics of winter storms. Key Points: Systematically omitting latent energy from different microphysical processes reveals large effects in a wintertime midlatitude cycloneOmitting warming from deposition results in less snowfall and a more eastward cyclone track, and vice versa for cooling from sublimationFall speed uncertainty has large impacts on the cloud microphysical characteristics, albeit with minor effects on snowfall [ABSTRACT FROM AUTHOR]

The structures of two Al(III) and Fe(III) β-diketonates with a γ-substituted ligand are studied by single crystal X-ray diffraction at 150(2) K. Crystallographic data for Al(γ-Me-hd)3 (I) are: space group , a = 10.855(1) Å, b = 11.129(1) Å, с = 11.894(1) Å, α = 85.634(3)°, F0200062 = 73.118(3)°, γ = 66.771(3)°, V = 1262.2(2) Å3, Z = 2, R1 = 0.0438. For Fe(γ-Me-hd)3 (II): space group P21/с, a = 10.0374(5) Å, b = 17.0798(7) Å, с = 15.7213(6) Å, F0200062 = 107.459(1)°, V = 2571.1(2) Å3, Z = 4, R1 = 0.0364. Compounds I and II are isotypical because their molecules have the same structure but crystallize in different crystal systems. The crystal structures of I and II are molecular and consist of discrete M(γ-Me-hd)3 (M = Al, Fe) molecules. Thermogravimetric studies show that complexes I and II are similarly volatile. For Cu(γ-Me-hd)2 complex (III) the saturated vapor pressure is measured by the Knudsen method in the temperature range 100-150 °C. Sublimation thermodynamic parameters are found and vapor thermolysis is investigated. [ABSTRACT FROM AUTHOR]

In this work experimental vapor pressures of hexahydro‐1,3,5‐trinitro‐1,3,5‐triazine (RDX) and hexahydro‐1,3,5‐trinitroso‐1,3,5‐triazine (TNX) were measured with transpiration method. Corresponding enthalpies of sublimation were determined to be (130.9±2.1) kJ mol−1 and (108.1±1.6) kJ mol−1, respectively. Along with the experimental data fitting equations are reported and p‐T data extrapolated to 298.15 K to be 0.71 μPa for RDX and 823 μPa for TNX. [ABSTRACT FROM AUTHOR]

The non-covalent interactions in organic molecules are known to drive their self-assembly to form molecular crystals. We compare, in the case of anthracene and against experimental (electronic-only) sublimation energy, how modern quantum-chemical methods are able to calculate this cohesive energy taking into account all the interactions between occurring dimers in both first-and second-shells. These include both O(N6)- and O(N5)-scaling methods, Local Pair Natural Orbital-parameterized Coupled-Cluster Single and Double, and Spin-Component-Scaled-Mo\ller-Plesset perturbation theory at second-order, respectively, as well as the most modern family of conceived density functionals: double-hybrid expressions in several variants (B2-PLYP, mPW2-PLYP, PWPB95) with customized dispersion corrections (-D3 and -NL). All-in-all, it is shown that these methods behave very accurately producing errors in the 1-2 kJ/mol range with respect to the experimental value taken into account the experimental uncertainty. These methods are thus confirmed as excellent tools for studying all kinds of interactions in chemical systems. [ABSTRACT FROM AUTHOR]

Scalable growth of high quality III-V semiconductor thin films on non-epitaxial substrates is of profound interest for photovoltaic applications. Here, we demonstrate growth of indium phosphide (InP) crystals directly on metal foils using closed-space sublimation (CSS) method. CSS allows effective transfer of source material to the substrate due to a small (∼2 mm gap between source and substrate) sublimation space. The crystallization kinetics are found to be dependent on the substrate temperature and pressure of the system. Importantly, experiments revealed that both InP nanowires and polycrystalline films could be obtained by tuning the growth conditions. Furthermore, utilizing a silicon dioxide mask, selective nucleation of InP on metal substrates was obtained. Photoluminescence measurements depict the high optical quality of the CSS grown InP. [ABSTRACT FROM AUTHOR]

Growth of epitaxial graphene on the C-face of SiC has been investigated. Using a confinement controlled sublimation (CCS) method, we have achieved well controlled growth and been able to observe propagation of uniform monolayer graphene. Surface patterns uncover two important aspects of the growth, i.e., carbon diffusion and stoichiometric requirement. Moreover, a new 'stepdown' growth mode has been discovered. Via this mode, monolayer graphene domains can have an area of hundreds of square micrometers, while, most importantly, step bunching is avoided and the initial uniformly stepped SiC surface is preserved. The stepdown growth provides a possible route towards uniform epitaxial graphene in wafer size without compromising the initial flat surface morphology of SiC. [ABSTRACT FROM AUTHOR]

Thin films of water under nanoscopic confinement are prevalent in natural and manufactured materials. To investigate the equilibrium and dynamic behavior of water in such environments, we perform molecular dynamics simulations of water confined between atomistically detailed hydrophobic plates at T = 298 K for pressures (-0.1) <= P <= 1.0 GPa and plate separations of 0.40 <= d <= 0.80 nm. From these simulations, we construct an expanded P-d phase diagram for confined water, and identify and characterize a previously unreported confined monolayer ice morphology. We also study the decompression-induced sublimation of bilayer ice in a d = 0.6 nm slit, employing principal component analysis to synthesize low-dimensional embeddings of the drying trajectories and develop insight into the sublimation mechanism. Drying is observed to proceed by the nucleation of a bridging vapor cavity at one corner of the crystalline slab, followed by expansion of the cavity along two edges of the plates, and the subsequent recession of the remaining promontory of bilayer crystal into the bulk fluid. Our findings have implications for the understanding of diverse phenomena in materials science, nanofluidics, and protein folding and aggregation. [ABSTRACT FROM AUTHOR]

Single crystals of three at bay area tetraphenoxy‐substituted perylene bisimide dyes are grown by vacuum sublimation. X‐ray analysis reveals the self‐assembly of these highly twisted perylene bisimides (PBIs) in the solid state via imide–imide hydrogen bonding into hydrogen‐bonded PBI chains. The crystallographic insights disclose that the conformation and sterical congestion imparted by the phenoxy substituents can be controlled by ortho‐substituents. Accordingly, whilst sterically less demanding methyl and isopropyl substituents afford double‐stranded PBI chains of complementary P and M atropo‐enantiomers, single hydrogen‐bonded chains of homochiral PBIs are observed for the sterically more demanding ortho‐phenyl substituents. Investigation of the absorption and fluorescence properties of microcrystals and thin films of these PBIs allow for an unambiguous interpretation of these exciton systems. Thus, the J‐aggregates of the double‐stranded crystals exhibit a much larger (negative) exciton coupling than the single‐stranded one, which in contrast has the higher solid‐state fluorescence quantum yield. [ABSTRACT FROM AUTHOR]

• Two major species (mono-oxo, di-oxo) occur within deposited ReO x on TiO 2 (P25). • Reversible T-dependent tuning of termination configuration of dispersed ReO x. • Mono-oxo species favored with increasing temperature at constant coverage. • Di-oxo species favored with increasing coverage at constant temperature. • Terminal stretching wavenumbers blue shift with increasing coverage. A holistic approach based on in situ molecular vibrational spectroscopy (Raman-FTIR and Raman-18O/16O isotope exchange) is applied to unravel the molecular structure and termination configuration of dispersed ReVIIO x on TiO 2 (P25) at surface densities of 0.16–2.5 Re/nm2 and temperatures of 120–430 °C. It is shown that the deposited ReVIIO x phase is heterogeneous, consisting of two distinct species: Species–I with mono-oxo termination configuration and Species–II with di-oxo termination configuration. A meticulous study of temperature and coverage effects shows that the mono-oxo Species–I prevails with increasing temperature and/or low surface coverage, whilst the di-oxo Species–II is favored at low temperature and/or high surface coverage. At constant coverage, a reversible temperature dependent di-oxo ↔ mono-oxo interconversion renders possible to tune the termination configuration of the majority deposited species. The wavenumbers of the mono-oxo and di-oxo terminal stretching modes undergo a blue shift with increasing surface coverage due to a cascade effect caused by the diversity of the support's hydroxyls' basicity. The wavenumber of the terminal ν Re = O mode of Species–I is at 1004 cm−1 for 0.48 Re/nm2 and gradually shifts to 1009 cm−1 for 2.5 Re/nm2; correspondingly, the symmetric stretching ν O = Re = O mode of the di-oxo Species–II is at 996 cm−1 for 0.48 Re/nm2 shifting to 1003 cm−1 for 2.5 Re/nm2. Above 275 °C part of the deposited ReO x phase is lost by sublimation. [ABSTRACT FROM AUTHOR]

Various precursors of divalent copper have been treated with the meta-disubstituted phenylene-based proligand POC(H)OP (1,3-(i-Pr2PO)2C6H4) with the objective of preparing classical pincer complexes (POCOP)CuX. However, in no case was such species obtained, presumably owing to the difficult C–H metallation step. Analogous reactions of monovalent precursors were also unsuccessful, whereas reaction of POC(H)OP with CuI under different conditions gave the non-metallated adducts {(μ, κP, --> κ P ′ --> -POC(H)OP)Cu(μ-Ι)}2, 1, {(μ, κP, --> κ P ′ --> -POC(H)OP)Cu2(μ-Ι)2(DMAP)2}, 2 (DMAP = 4-dimethylaminopyridine), and {(μ, κP, --> κ P ′ --> -POC(H)OP)Cu2(μ3-Ι)2}2, 3. Treating 1 with DMAP gave the adduct 2, whereas 3 could be obtained by treating 1 with BuLi or by sublimation of 1. The solid state structures of these complexes revealed the tetrahedral geometry that might be anticipated for the d10 Cu(I) centers, in addition to fairly close I–H distances; on the other hand, no C–H interaction (agostic or otherwise) was observed with the Cu centers in any of these structures. The unsuccessful metallation of the C(2)–H moiety is thought to be a result of the strong preference of monovalent copper center to form bridging interactions with iodide and the POC(H)OP ligand; this appears to prevent the approach of the central carbon of the ligand to the Cu centers. [ABSTRACT FROM AUTHOR]

The continuous improvement of analytical procedures using multi‐collector technologies in ICP‐mass spectrometry has led to an increased demand for isotope standards with improved homogeneity and reduced measurement uncertainty. For magnesium, this has led to a variety of available standards with different quality levels ranging from artefact standards to isotope reference materials certified for absolute isotope ratios. This required an intercalibration of all standards and reference materials, which we present in this interlaboratory comparison study. The materials Cambridge1, DSM3, ERM‐AE143, ERM‐AE144, ERM‐AE145, IRMM‐009 and NIST SRM 980 were cross‐calibrated with expanded measurement uncertainties (95% confidence level) of less than 0.030‰ for the δ25/24Mg values and less than 0.037‰ for the δ26/24Mg values. Thus, comparability of all magnesium isotope delta (δ) measurements based on these standards and reference materials is established. Further, ERM‐AE143 anchors all magnesium δ‐scales to absolute isotope ratios and therefore establishes SI traceability, here traceability to the SI base unit mole. This applies especially to the DSM3 scale, which is proposed to be maintained. With ERM‐AE144 and ERM‐AE145, which are product and educt of a sublimation–condensation process, for the first time a set of isotope reference materials is available with a published value for the apparent triple isotope fractionation exponent θapp, the fractionation relationship ln α(25/24Mg)/ln α(26/24Mg). [ABSTRACT FROM AUTHOR]

Dans le cadre du présent travail, nous proposons d'appréhender l'épidémie mondiale de coronavirus de type COVID-19, en tant que phénomène sociobiologique. Pour mener à bien notre réflexion, nous nous appuierons sur une expérience d'écoute psychologique d'orientation psychanalytique menée lors des attentats de Nice ayant eu lieu en 2016, et poursuivie ce jour dans le contexte pandémique actuel. Plus précisément, nous nous pencherons sur le signifiant « victime », avec tout ce qu'il engage comme questionnements quant au sujet. Notre proposition sera de considérer le statut de victime comme une traversée. Au cours de cette dernière, il est important que la souffrance des sujets soit écoutée, reconnue, jugée et indemnisée. Et cela, afin que chacun puisse trouver sa façon singulière de donner sa réponse au réel du virus, tel qu'il s'est imposé à nous ; mais, nous verrons aussi que l'une des conclusions possibles de cette traversée consiste à passer par des formes diverses de sublimation. As part of this work, we propose to understand the global epidemic of COVID-19 coronavirus, as a sociobiological phenomenon. To carry out our reflection, we will base ourselves on a psychological listening experience (in a psychoanalytic orientation) conducted during the Nice attacks in 2016, and continued today, during the current pandemic context. More specifically, we will look at the signifier "victim", including all that it involves as questions about the subject. Our proposal will be to consider the victim status as a crossing. During this one, it is important that the suffering of the subjects is listened to, recognised, judged and compensated. In order for this to happen, everyone can find his own way of giving an answer to the reality of the virus, as it has imposed itself on us; but we will also see that one of the possible conclusions of this crossing consists in going through various forms of sublimation. [ABSTRACT FROM AUTHOR]

Atomic/molecular layer deposition (ALD/MLD) is strongly emerging as the state-of-the-art gas-phase fabrication technique for novel functional inorganic-organic thin-film materials. In the actual ALD/MLD process development, selecting the proper sublimation temperatures for the inorganic and organic precursors is an important task. In particular, the latter ones tend to require higher sublimation temperatures. In this work, we systematically investigate a representative set of most common ALD/MLD organic precursors using low-pressure (4 mbar) thermogravimetric (TG) analysis. The onset temperature (TGonset) where the weight loss starts is found to well foretell us the optimal precursor source temperature (TMLD) for ALD/MLD; typically, the TMLD value used in a practical ALD/MLD experiment is lower by approximately 14% than the TGonset value. Moreover, we discuss the possibility to utilize the melting point of the compound as a starting point if such vacuum TG measurements are not available. [ABSTRACT FROM AUTHOR]

Soil hydrothermal regime of the active layer in the permafrost regions of the Qinghai‐Tibet Plateau (QTP) is important to the underlying permafrost and the climate change dynamics in Asia. However, a large bias still exists in current land surface models in the representation of soil temperature and moisture. This study assessed and augmented the Noah land surface model with multiparameterization options (Noah‐MP) for simulating soil hydrothermal dynamics at the Tanggula (alpine meadow) and Beiluhe (alpine swamp) stations located in the permafrost regions of the QTP. The results showed that the default Noah‐MP tended to underestimate soil temperature and moisture. Specifically, the default model overestimated the snow depth and duration due to the low snow sublimation rate. This resulted in a cold deviation in the soil temperature at two stations. Such underestimation was reduced by introducing a scheme that considered the sublimation loss from wind. Moreover, the remaining cold bias in the soil profiles of two stations was greatly resolved by a combined scheme of roughness length for heat (Z0h) and undercanopy aerodynamic resistance (ra,g). A soil thermal conductivity scheme, which can produce more realistic soil thermal conductivity in frozen soil, further improved the deep soil temperature simulation. The consideration of soil organic matter could mitigate the underestimation of the shallow soil moisture to some extent, but this improvement was more obvious at the Tanggula station, which had coarser mineral soil than the Beiluhe station. Key Points: Noah‐MP tends to underestimate soil temperature and moistureAdding snow sublimation from wind, combination of Z0h and ra,g, and realistic frozen soil thermal conductivity improves soil temperatureOrganic matter plays an important role in functioning coarse soil moisture [ABSTRACT FROM AUTHOR]

The so-called buffer layer (BL) is a carbon rich reconstructed layer formed during SiC (0001) sublimation. The covalent bonds between some carbon atoms in this layer and underlying silicon atoms makes it different from epitaxial graphene. We report a systematical and statistical investigation of the BL signature and its coupling with epitaxial graphene by Raman spectroscopy. Three different BLs are studied: bare buffer layer obtained by direct growth (BL 0), interfacial buffer layer between graphene and SiC (c-BL 1) and the interfacial buffer layer without graphene above (u-BL 1). To obtain the latter, we develop a mechanical exfoliation of graphene by removing an epoxy-based resin or nickel layer. The BLs are ordered-like on the whole BL growth temperature range. BL 0 Raman signature may vary from sample to sample but forms patches on the same terrace. u-BL 1 share similar properties with BL 0 , albeit with more variability. These BLs have a strikingly larger overall intensity than BL with graphene on top. The signal high frequency side onset upshifts upon graphene coverage, unexplainable by a simple strain effect. Two fine peaks (1235, 1360 cm−1), present for epitaxial monolayer and absent for BL and transferred graphene. These findings point to a coupling between graphene and BL. Image 1 [ABSTRACT FROM AUTHOR]

The volatile composition of a planet is determined by the inventory of gas and ice in the parent disk. The volatile chemistry in the disk is expected to evolve over time, though this evolution is poorly constrained observationally. We present Atacama Large Millimeter/submillimeter Array observations of C18O, C2H, and the isotopologues H13CN, HC15N, and DCN toward five Class 0/I disk candidates. Combined with a sample of 14 Class II disks presented in Bergner et al., this data set offers a view of volatile chemical evolution over the disk lifetime. Our estimates of C18O abundances are consistent with a rapid depletion of CO in the first ∼0.5–1 Myr of the disk lifetime. We do not see evidence that C2H and HCN formation are enhanced by CO depletion, possibly because the gas is already quite under-abundant in CO. Further CO depletion may actually hinder their production by limiting the gas-phase carbon supply. The embedded sources show several chemical differences compared to the Class II stage, which seem to arise from shielding of radiation by the envelope (impacting C2H formation and HC15N fractionation) and sublimation of ices from infalling material (impacting HCN and C18O abundances). Such chemical differences between Class 0/I and Class II sources may affect the volatile composition of planet-forming material at different stages in the disk lifetime. [ABSTRACT FROM AUTHOR]

This work provides a qualitative description of the pellet response to the ambient runaway electrons. For ITER-relevant parameters, our estimates suggest that the cryogenic pellets will be sublimated instantly at the edge of the runaway beam. The subsequent rapid expansion of the sublimated material spreads the impurities over the poloidal cross-section of a tokamak on a millisecond time scale prior to the complete ionization of the expanding cloud. The injected solid pellet turns into a rapidly expanding gas cloud before it reaches the core of the runaway beam. As a result, the pellet acts similar to the massive gas injection. [ABSTRACT FROM AUTHOR]

Hot corino chemistry and warm carbon chain chemistry (WCCC) are driven by gas–grain interactions in star-forming cores: radical–radical recombination reactions to form complex organic molecules (COMs) in the ice mantle, sublimation of CH4 and COMs, and their subsequent gas-phase reactions. These chemical features are expected to depend on the composition of the ice mantle, which is set in the prestellar phase. We calculated the gas–grain chemical reaction network considering a layered ice mantle structure in star-forming cores to investigate how the hot corino chemistry and WCCC depend on the physical condition of the static phase before the onset of gravitational collapse. We found that WCCC becomes more active if the temperature is lower, or the visual extinction is lower in the static phase, or the static phase is longer. The dependence of hot corino chemistry on the static-phase condition is more complex. While CH3OH is less abundant in the models with a warmer static phase, some COMs are formed efficiently in those warm models because there are various formation paths of COMs. If the visual extinction is lower, photolysis makes COMs less abundant in the static phase. Once the collapse starts and visual extinction increases, however, COMs can be formed efficiently. The duration of the static phase does not largely affect COM abundances. The chemical diversity between prototypical hot corinos and hybrid sources, in which both COMs and carbon chains are reasonably abundant, can be explained by the variation of prestellar conditions. Deficiency of gaseous COMs in prototypical WCCC sources is, however, hard to reproduce within our models. [ABSTRACT FROM AUTHOR]

Spherical ZrB 2 -SiC powder with a eutectic phase was synthesised via induction plasma spheroidisation (IPS) in this study. The influence of H 2 flow and reaction chamber pressure on the powder microstructure was investigated during the induction plasma spheroidisation process. The powders have an evidently better fluidity (< 44 s/50 g) and a larger apparent density (>1.65 g/cm3) after IPS treatment. With an increase in H 2 flow or pressure, the shape of surface grains successively shows an irregular, hexagonal, and rectangular shape because the grain growth mechanism changes from surface energy to diffusion activation energy. There is serious mass loss of SiC on the surface because of pure active oxidation and sublimation during the IPS treatment. The cross section of the ZrB 2 -SiC powder indicates a dense microstructure comprising coarse ZrB 2 and intergranular eutectic phases. Furthermore, the corresponding ZrB 2 -SiC bulk ceramics and coating fabricated using the IPS-treated powder both contain eutectic phase. Unlabelled Image • The best fluidity and apparent density of powder is 21.116 s/50 g and 3.1024 g/cm3. • The ZrB 2 growth is controlled by surface energy and diffusion activation energy. • SiC loss is caused by sublimation, active oxidation of SiC and SiO 2 volatilisation. • The eutectic can improve the densification and properties of powder and coating. [ABSTRACT FROM AUTHOR]

210Pb is an environmental radionuclide with a half-life of 22.3 years, formed in the atmosphere via radioactive decay of radon (222Rn). 222Rn itself is a noble gas with a half-life of 3.8 days and is formed via radioactive decay of uranium (238U) contained in the Earth crust from where it constantly emanates into the atmosphere. 210Pb atoms attach to aerosol particles, which are then deposited on glaciers via scavenging with fresh snow. Due to its half-life, ice cores can be dated with this radionuclide over roughly one century, depending on the initial 210Pb activity concentration. Optimum 210Pb dating is achieved for cold glaciers with no – or little – influence by percolating meltwater. This paper presents an overview which not only includes dating of cold glaciers but also some special cases of 210Pb applications in glaciology addressing temperate glaciers, glaciers with negative mass balance, sublimation processes on glaciers in arid regions, determination of annual net snow accumulation as well as glacier flow rates. [ABSTRACT FROM AUTHOR]

Atomic force microscopy, Kelvin-probe microscopy and Raman spectroscopy have been used to examine graphene films grown by thermal decomposition of the Si face of semi-insulating substrates of 6H-SiC and 4H-SiC polytypes in the atmosphere of argon. It was demonstrated that the quality of graphene grown on substrates of various polytypes at identical technological growth regimes is about the same. A conclusion was made that the differences in crystal structure between 6H-SiC and 4H-SiC does not lead to significant dissimilarities in the mechanism of sublimation of silicon carbide components from the surface of a crystal and in that of graphene crystallization. [ABSTRACT FROM AUTHOR]

The problem of one-dimensional intense evaporation waves is considered. It concerns with unsteady instantaneous expansion of overheated material vapors into a vacuum or a low-density medium from a plate, a cylinder, or a sphere, whereupon constant ("sonic") boundary conditions are imposed on the surfaces of these bodies. [ABSTRACT FROM AUTHOR]

Growth of organic thin films using physical vapor deposition typically follows a three-dimensional mode, resulting in a rough surface, which undermines their application potential. To address this issue, we have studied the effect of electric field and temperature on the growth dynamics, especially the heterogeneous nucleation process, of croconic acid (CA) films, taking advantage of the large dipole moment of the molecules and the ferroelectric polarization of the molecular crystals. We found that the nucleation rate reaches the maximum at intermediate temperature, and the electric field shifts the maximum nucleation rate towards lower temperature. An analysis using the classical nucleation theory suggests that the electric field decreases the sublimation temperature, increases the wetting angle, and decreases the surface diffusion barrier. These results provide important insight into the growth of molecular crystal films under electric fields and pave the way to fabricating films with better surface characteristics for molecular ferroelectric films. [ABSTRACT FROM AUTHOR]

Films of (111)-textured Cu, Ni, and CuxNiy were evaluated as substrates for chemical vapor deposition of graphene. A metal thickness of 400 nm to 700 nm was sputtered onto a substrate of α-Al2O3(0001) at temperatures of 250 °C to 650 °C. The films were then annealed at 1000 °C in a tube furnace. X-ray and electron backscatter diffraction measurements showed all films have (111) texture but have grains with in-plane orientations differing by 60°. The in-plane epitaxial relationship for all films was [110]metal||[1010]Al2O3. Reactive sputtering of Al in O2 before metal deposition resulted in a single in-plane orientation over 97% of the Ni film but had no significant effect on the Cu grain structure. Transmission electron microscopy showed a clean Ni/Al2O3 interface, confirmed the epitaxial relationship, and showed that formation of the 60° twin grains was associated with features on the Al2O3 surface. Increasing total pressure and Cu vapor pressure during annealing decreased the roughness of Cu and CuxNiy films. Graphene grown on the Ni(111) films was more uniform than that grown on polycrystalline Ni/SiO2 films, but still showed thickness variations on a much smaller length scale than the distance between grains. [ABSTRACT FROM AUTHOR]

A benchmark for non-covalent interactions in solids (C21) based on the experimental sublimation enthalpies and geometries of 21 molecular crystals is presented. Thermal and zero-point effects are carefully accounted for and reference lattice energies and thermal pressures are provided, which allow dispersion-corrected density functionals to be assessed in a straightforward way. Other thermal corrections to the sublimation enthalpy (the 2RT term) are reexamined. We compare the recently implemented exchange-hole dipole moment (XDM) model with other approaches in the literature to find that XDM roughly doubles the accuracy of DFT-D2 and non-local functionals in computed lattice energies (4.8 kJ/mol mean absolute error) while, at the same time, predicting cell geometries within less than 2% of the experimental result on average. The XDM model of dispersion interactions is confirmed as a very promising approach in solid-state applications. [ABSTRACT FROM AUTHOR]

We have studied, via laser absorption spectroscopy, the velocity distribution of 7Li atoms released from cryogenic matrices of solid neon or molecular hydrogen. The Li atoms are implanted into the Ne or H2 matrices - grown onto a sapphire substrate - by laser ablation of a solid Li or LiH precursor. A heat pulse is then applied to the sapphire substrate sublimating the matrix together with the isolated atoms. With a NiCr film resistor deposited directly onto the sapphire substrate we are able to transfer high instantaneous power to the matrix, thus reaching a fast sublimation regime. In this regime the Li atoms can get entrained in the released matrix gas, and we were also able to achieve matrix sublimation times down to 10 μs for both H2 or Ne matrix, enabling us to proceed with the trapping of the species of our interest such as atomic hydrogen, lithium, and molecules. The sublimation of the H2 matrix, with its large center-of-mass velocity, provides evidence for a new regime of one-dimensional thermalization. The laser ablated Li seems to penetrate the H2 matrix deeper than it does in Ne. [ABSTRACT FROM AUTHOR]

Fully relativistic, four-component density functional theory electronic structure calculations were performed for MBr5, MOBr3, MBr6-, KMBr6, and MBr5Cl- of group-5 elements Nb, Ta, and element 105, Db, with the aim to predict adsorption behaviour of the bromides in gas-phase chromatography experiments. It was shown that in the atmosphere of HBr/BBr3, the pentabromides are rather stable, and their stability should increase in the row Nb < Db < Ta. Several mechanisms of adsorption were considered. In the case of adsorption by van der Waals forces, the sequence in volatility of the pentabromides should be Nb < Ta < Db, being in agreement with the sublimation enthalpies of the Nb and Ta pentabromides. In the case of adsorption by chemical forces (on a quartz surface modified with KBr/KCl), formation of the MBr5L- (L = Cl, Br) complex should occur, so that the volatility should change in an opposite way, i.e., Nb > Ta > Db. This sequence is in agreement with the one observed in the 'one-atom-at-a-time' chromatography experiments. Some other scenarios, such as surface oxide formation were also considered but found to be irrelevant. [ABSTRACT FROM AUTHOR]

We investigate the low-temperature magneto-transport properties of monolayer epitaxial graphene films formed on the Si-face of semi-insulating 4 H-SiC substrates by a high-temperature sublimation process. A high-k top-gate on the epitaxial graphene is realized by inserting a fully oxidized nanometer-thin aluminum film as a seeding layer, followed by an atomic layer deposition process. At low temperatures, the devices demonstrate a strong field effect by the top gate with an on/off ratio of ∼7 and an electron mobility up to ∼3250 cm2/Vs. After the observation of the half-integer quantum-Hall effect for monolayer epitaxial graphene films, detailed magneto-transport measurements have been carried out including varying densities, temperatures, magnetic fields, and currents. We study the width of the distinguishable quantum-Hall plateau to plateau transition (Landau level index n = 0 to n = 1) as temperature (T) and current are varied. For both gate voltage and magnetic field sweeps and T > 10 K, the transition width goes as T-κ with exponent k ∼ 0.42. This universal scaling exponent agrees well with those found in III-V heterojunctions with short-range alloy disorders and in exfoliated graphene. [ABSTRACT FROM AUTHOR]

We have studied, via laser absorption spectroscopy, the velocity distribution of 7Li atoms released from a solid neon matrix at cryogenic temperatures. The Li atoms are implanted into the Ne matrix by laser ablation of a solid Li precursor. A heat pulse is then applied to the sapphire substrate sublimating the matrix together with the isolated atoms at around 12 K. We find interesting differences in the velocity distribution of the released Li atoms from the model developed for our previous experiment with Cr [R. Lambo, C. C. Rodegheri, D. M. Silveira, and C. L. Cesar, Phys. Rev. A 76, 061401(R) (2007)]. This may be due to the sublimation regime, which is at much lower flux for the Li experiment than for the Cr experiment, as well as to the different collisional cross sections between those species to the Ne gas. We find a drift velocity compatible with Li being thermally sublimated at 11-13 K, while the velocity dispersion around this drift velocity is low, around 5-7 K. With a slow sublimation of the matrix we can determine the penetration depth of the laser ablated Li atoms into the Ne matrix, an important information that is not usually available in most matrix isolation spectroscopy setups. The present results with Li, together with the previous results with Cr suggest this to be a general technique for obtaining cryogenic atoms, for spectroscopic studies, as well as for trap loading. The release of the isolated atoms is also a useful tool to study and confirm details of the matrix isolated atoms which are masked or poorly understood in the solid. [ABSTRACT FROM AUTHOR]

The structural evolution, epitaxy, and sublimation temperature of silver nanoclusters (NCs) on TiO2 (110) surfaces prepared in two different ways are reported here based on a combination of in situ reflection high energy electron diffraction characterization and ex situ electron imaging. It is shown that silver NCs deposited at room temperature on oxidized TiO2 (110) surfaces are unable to form a single epitaxy prior to sublimation. When heated close to sublimation, two particle orientations dominate: (111)Ag∥(110)TiO2, [-110]Ag∥[001]TiO2 and (112)Ag∥(110)TiO2, [-110]Ag∥[001]TiO2. Single twinned silver NCs are found to be stable even at temperatures close to sublimation. On the other hand, silver NCs prepared similarly on reduced TiO2 (110) surfaces behave very differently when heated to higher temperatures. On the reduced surface, the NCs are able to evolve into a single epitaxy-(111)Ag∥(110)TiO2, [-110]Ag∥[001]TiO2. The sublimation temperature for silver NCs on the reduced surface is found to be less than those on the oxidized surface by about 35°. The epitaxy formed by annealing is the same as the one formed by depositing silver onto reduced TiO2 (110) at 350 °C (>0.5 Tm of Ag). [ABSTRACT FROM AUTHOR]

Homogeneous nucleation rates of the n-alkanes (CiH2i+2; i=7–10) were determined by combining information from pressure trace measurements and small angle x-ray scattering (SAXS) experiments in a supersonic Laval nozzle. The condensible vapor pressure pJ max, the temperature TJ max, the characteristic time ΔtJ max, and supersaturation SJ max corresponding to the peak nucleation rate Jmax were determined during the pressure trace measurements. These measurements also served as the basis for the subsequent SAXS experiments. Fitting the radially averaged SAXS spectrum yielded the mean droplet radius , 5≤/nm≤31, the width of the aerosol size distribution σ, 2≤σ/nm≤6, and the particle number density N, 7×1010

31P NMR spectroscopy has been used to elucidate the role of glass-forming sugars in the preservation of dipalmitoylphosphatidylcholine (DPPC) lipid bilayers. 31P wideline NMR spectra of freeze-dried pure DPPC, DPPC/trehalose, DPPC/glucose, and DPPC/hydroxyethyl starch (HES) mixtures collected in the temperature range of 25–80 °C have been simulated to obtain quantitative information about rotational dynamics and orientation of the lipid head groups in these media. In the case of pure DPPC, DPPC/glucose, and DPPC/HES, the gel-to-liquid crystalline phase transition of DPPC bilayer is characterized by a sudden increase in the rate of rotational diffusion of the PO4 head groups near 40 °C. The corresponding rotational jump frequency increases from a few kilohertz in the gel phase to at least several megahertz in the liquid crystalline phase. On the other hand, in the case of DPPC/trehalose mixture the temperature of this onset of rapid head group dynamics is increased by ∼10 °C. Trehalose reduces the lipid head group motions most effectively in the temperature range of T≤50 °C relevant for biopreservation. Additionally, and possibly more importantly, trehalose is found to strongly restrict any change in the orientation of the diffusion axis of the PO4 head groups during the phase transformation. This unique ability of trehalose to maintain the dynamical and orientational rigidity of lipid head groups is likely to be responsible for its superior ability in biopreservation. [ABSTRACT FROM AUTHOR]

Angular distributions of 13 different metals ejected by laser ablation using fourth harmonics (wavelength=266 nm) of neodymium doped yttrium aluminum garnet laser and a fluence close to near-threshold value (2.3 J/cm2) have been investigated with a high angular resolution. The angular distribution which is characterized by the exponent n of cosn θ distribution showed very broad range of values between 3 and 24 for different metals. A simple relation that the exponent n is proportional to the square root of particle atomic weight as reported previously has not been observed. Instead, a general trend has been found that the metals with higher sublimation energy such as Ta and Zr show narrower angular distribution than those with lower sublimation energy such as Sn and In. While the sublimation energy of metals has a great influence on the angular distribution of ejected atoms, a simple consideration suggests that their thermal conductivity and specific heat have little effect on it. [ABSTRACT FROM AUTHOR]

Photoluminescence (PL) measurements were used to study the effect of postdeposition treatments by annealing and CdCl2 activation on polycrystalline CdS layer grown by close-spaced sublimation (CSS) and chemical bath deposition (CBD). CdS films were either annealed in a temperature range of 200–600 °C or CdCl2 treated between 300–550 °C. The development of “red,” “intermediate orange,” “yellow,” and “green” luminescence bands is discussed in comparison with PL assignments found in literature. PL spectra from CdS layer grown by CSS are dominated by the yellow band with transitions at 2.08 and 1.96 eV involving (Cdi-A), (VS-A) complex states where A represents an acceptor. Green luminescence bands are observed at 2.429 and 2.393 eV at higher annealing temperature of 500–600 °C or CdCl2 treatment above 450 °C, and these peaks are associated with zero and a longitudinal optical phonon replica of “free-to-bound” transitions. As grown CBD-CdS films show a prominent red band with four main peaks located at 1.43, 1.54, 1.65, and 1.77 eV, believed to be phonon replicas coupled with local vibrational modes. This remains following postdeposition treatment. The red luminescence is associated with VS surface states and in the case of CdCl2 treatment with (VCd-ClS) centers. Postdeposition treatments of CBD and CdS promote the evolution of an intermediate orange band at 2.00 eV, most likely a donor-acceptor pair, and a yellow band at 2.12 eV correlated with (Cdi-VCd) centers. The green luminescence bands observed at 2.25 and 2.34 eV are associated with transitions from deep donor states (e.g., Cdi) to the valence band. These states form due to crystallinity enhancement and lattice conversion during annealing or CdCl2 activation. Observed changes in PL bands provide detailed information about changes in radiative recombination centers in CdS layer, which are suggested to occur during device processing of CdTe/CdS thin film solar cells. [ABSTRACT FROM AUTHOR]

A three-dimensional numerical finite element modeling method is applied to compare interfacial residual thermal stress distribution in AlN single crystals grown by using different substrates such as silicon carbide, boron nitride, tungsten, tantalum carbide, and niobium carbide. A dimensionless coordinate system is used which reduces the numbers of computations and hence simplifies the stress analysis. All components of the stress distribution, both in the film and in the substrate, including the normal stress along the growth direction as well as in-plane normal stresses and shear stresses are fully investigated. This information about the stress distribution provides insight into understanding and controlling the AlN single crystal growth by the sublimation technique. The normal stress in the film at the interface along the growth direction and the shear stresses are zero except at the edges, whereas in-plane stresses are nonzero. The in-plane stresses are compressive when TaC and NbC substrates are used. A small compressive stress might be beneficial in prohibiting crack growth in the film. The compressive stress in the AlN is lower for the TaC substrate than that for the NbC. Tensile in-plane stresses are formed in the AlN for 6H-SiC, BN, and W substrates. This tensile stress in the film is detrimental as it will assist in the crack growth. The stress concentration at the edges of the AlN film at the interface is compressive in nature when TaC and NbC are used as a substrate. This causes the film to bend downward (i.e., convex shape) and assist it to adhere to the substrate. The AlN film curves upward or in a concave shape when SiC, BN, and W substrates are used since the stress concentration at the edges of the AlN film is tensile at the interface and this may cause detachment of the film from the substrate. [ABSTRACT FROM AUTHOR]

Thermoelectric (TE) properties of the coevaporated Bi2Te3 and Sb2Te3 films are measured from 100 to 300 K for Seebeck coefficient αS and from 5 to 300 K for electrical resistivity ρe, mobility μe, and Hall coefficient RH. For the low-temperature characterization of TE films, the conditions for coevaporation deposition of Bi, Te, and Sb to form Bi2Te3 and Sb2Te3 films are also investigated, including substrate material, substrate temperature Tsub, and elemental flux ratio (FR). The resublimation of Te occurring above 473 K significantly affects the film composition and quality. Our optimal deposition conditions for Bi2Te3 films are Tsub=533 K and FR=2.4, and those for Sb2Te3 films are Tsub=503 K and FR=3.0. The TE properties of both films are strongly temperature dependent, while Bi2Te3 films show a stronger temperature dependence than Sb2Te3 films due to different major scattering mechanisms. αS of both the coevaporated films are close to or higher than those of bulk materials, but ρe is much higher (due to lower carrier concentrations for Sb2Te3 films and lower μe for Bi2Te3 films). Also, no freeze-out regime is found for both Bi2Te3 and Sb2Te3 films at low temperatures. The room-temperature power factors of αS2/ρe for Bi2Te3 and Sb2Te3 films are 2.3 and 2.0 mW/K2 m, and the maxima are 2.7 mW/K2 m for Bi2Te3 at T=220 K and 2.1 mW/K2 m for Sb2Te3 at T=280 K. Shadow mask technique is successfully used for the micropatterning (20 μm) of TE films with no significant change in properties. [ABSTRACT FROM AUTHOR]

We employed organic heterojunction films as all-organic connecting units to fabricate tandem organic photovoltaic cells by continuous deposition. The all-organic connecting units with a better transparence and a lower sublimation temperature became an effective recombination center for electrons and holes photogenerated in front cell and back cell, respectively. Tunnel mechanism was proposed to explain the combination of photogenerated carrier. In the optimized tandem solar cell in which tin phthalocyanine dichloride/copper hexadecafluorophthalocyanine heterojunction is used as connecting units, the open-circuit voltage of 1.04 V is double of the single unit cells, and the PCE was increased by 60%, reaching to 1.8%. Therefore, it is an effective way to use the organic heterojunction films as connecting units in organic tandem cells to improve the device performance dramatically. [ABSTRACT FROM AUTHOR]

Single and multiwalled nitrogen-doped carbon nanotubes were grown by chemical vapor deposition varying the feedstock composition between pure acetonitrile and ethanol/acetonitrile mixtures. The advantage of using C/N sources that develop close vapor pressure values has been used in order to elucidate the effects of the reaction atmosphere in the synthesis of N-doped nanotubes. Our findings show that the morphology of the nanotube material depends strongly on the composition of the reaction atmosphere. When carrying out the experiments in an atmosphere solely determined by the vapor pressure of the feedstock components, improved homogeneity is achieved with pure C/N sources or low concentration of the foreign solute. Under these conditions the temperature has strong influence in the diameter distribution. [ABSTRACT FROM AUTHOR]

Homogeneous nucleation of argon droplets has been measured with a newly designed cryogenic nucleation pulse chamber presented already in a previous paper [Fladerer and Strey, J. Chem. Phys. 124, 16 (2006)]. Here we present the first systematic nucleation onset data for argon measured in a temperature range from 42 to 58 K and for vapor pressures from 0.3 to 10 kPa. For these data we provide an analytical fit function. From the geometry of the optical detection system and the time of nucleation the experimental nucleation-rate range can be estimated. This allows a comparison of the data with the predictions of classical nucleation theory. We found 16–26 orders of magnitude difference between theory and experiment, and a too strong theoretical dependence of the nucleation rate on temperature. A comparison with the self-consistent theory of Girshick and Chiu [J. Chem. Phys. 93, 1273 (1990)] showed improved temperature dependence but still discrepancies of 11–17 orders of magnitude compared to experimental data. The thermodynamically consistent theory of Kashchiev [J. Chem. Phys. 118, 1837 (2003)] was found to agree rather well with experiment in respect to the temperature dependence and to predict rates about 5-7 orders of magnitude below the experimental ones. With the help of the Gibbs-Thomson equation we were able to evaluate the size of the critical nucleus to be 40–80 argon atoms. [ABSTRACT FROM AUTHOR]

The authors present new measurements of thermal and electrical properties for two porphyrin derivatives. They determine their sublimation enthalpy from the temperature dependence of the effusive beam intensity. The authors study H2TPP and Fe(TPP)Cl in matter-wave interferometry. Both molecules have nearly equal de Broglie wavelengths but different internal characteristics: only Fe(TPP)Cl exhibits an electric dipole moment of about 2.7 D and the authors discuss its influence on the molecular interference pattern. The authors add an external electric force field to the interferometer and use it to measure the scalar polarizability. They compare their experimental values α(H2TPP)=105±4±6 Å3 and α(Fe(TPP)Cl)=102±9±6 Å3 to ab initio calculations and they discuss the influence of thermal excitations on the polarizability. [ABSTRACT FROM AUTHOR]

Using molecular dynamics simulations, The authors studied the solid-vapor coexistence states of Lennard-Jones methane confined in slit-shaped graphite nanopores. Both the intrapore solid and extrapore vapor were simulated using a unit cell which they previously developed. Frozen critical condensates in the pores were cooled stepwise, and the equilibrium vapor pressure was determined at each temperature. The obtained solid-vapor coexistence curves were remarkably lower than that of the bulk phase. Their thermodynamic model successfully predicts the simulation results without the need to introduce any adjustable parameter, and thus proves its reliability. [ABSTRACT FROM AUTHOR]

The authors performed Gibbs ensemble simulations on the vapor-liquid equilibrium of water to investigate the influence of incorporating intramolecular degrees of freedom in the simple point charge (SPC) water model. Results for vapor pressures, saturation densities, heats of vaporization, and the critical point for two different flexible models are compared with data for the corresponding rigid SPC and SPC/E models. They found that the introduction of internal vibrations, and also their parametrization, has an observable effect on the prediction of the vapor-liquid coexistence curve. The flexible SPC/Fw model, although optimized to describe bulk diffusion and dielectric constants at ambient conditions, gives the best prediction of saturation densities and the critical point of the examined models. [ABSTRACT FROM AUTHOR]

A parameter-free model using ab initio chemical potentials is developed to analyze transport and growth rate in sublimation deposition of AlN. The model predicts that spontaneous mass transport is limited by a chemical potential barrier, which in turn determines the range of effective source-crystal temperature drops. The contributions to the barrier from Al and N2, which are the dominant species in the gas phase, almost cancel so that the barrier is sensitive to trace species such as Al3N. This result explains the experimentally observed decrease in growth rate with increasing inlet pressure as being due to a decreasing Al3N concentration. Using first principles chemical potentials may present potential opportunities to study other practical systems in which trace species plays an important role but where transport coefficients have to be determined empirically. Examples include atmospheric transport of contaminants and photosynthetic assimilation of CO2. [ABSTRACT FROM AUTHOR]

We present a new thermodynamic integration method that directly connects the vapor and solid phases by a reversible path. The thermodynamic integration in the isothermal-isobaric ensemble yields the Gibbs free energy difference between the two phases, from which the sublimation temperature can be easily calculated. The method extends to the binary mixture without any modification to the integration path simply by employing the isothermal-isobaric semigrand ensemble. The thermodynamic integration, in this case, yields the chemical potential difference between the solid and vapor phases for one of the components, from which the binary sublimation temperature can be calculated. The coexistence temperatures predicted by our method agree well with those in the literature for single component and binary Lennard-Jones systems. [ABSTRACT FROM AUTHOR]

• Vapor pressure of drug were determined and sublimation thermodynamics were evaluated. • Solubility of nifedipine was measured in buffers (pH 2.0 and 7.4), n-hexane and 1-octanol. • Thermodynamic parameters of solubility and solvation were calculated. • Solid state of compound was characterized by DSC and PXRD. • Transfer process nifedipine between aqueous and organic phases was discussed. The saturated vapour pressure of the cardiovascular drug nifedipine is measured within the temperature range (390.15–404.15) K by the inert gas-carrier method. The thermodynamic functions of sublimation of the compounds are calculated at a reference temperature. The standard molar enthalpy of nifedipine sublimation is found to be equal to 144.8 kJ∙mol−1. The drug solubility in solvents modeling various media of the human body is determined in the temperature range (293.15–313.15) K. In the ascending order of solubility values of the studied compound, the solvents can be arranged as follows: buffer pH 7.4, buffer pH 2.0, n -hexane, 1-octanol. The solute–solvent intermolecular interactions are discussed based on the thermodynamic functions of solubility, solvation and transfer. [ABSTRACT FROM AUTHOR]

This study examines the differences in using two primary methods for adsorbing trimethylphosphine oxide (TMPO) onto acid catalysts and their influence on the NMR spectra of TMPO-loaded zeolites. The findings show that TMPO molecules interact with both Brønsted and Lewis acid sites, and that the amount of (TMPO) 2 H+ dimers formed increases with the amount of TMPO added. The use of dichloromethane as a solvent inhibits the formation of dimers and crystalline TMPO but may lead to inaccurate estimations of acid site strength and quantification due to interactions with residual solvent molecules. The gas-phase method is preferred for adsorbing TMPO onto zeolites, but caution is needed to avoid forming a high number of dimers that ca pose challenges in the interpretation of the NMR spectra. [Display omitted] • TMPO was successfully adsorbed onto HZSM-5 zeolites using dichloromethane as solvent and through sublimation of TMPO. • Even under high vacuum conditions, it is difficult to remove solvent molecules from zeolite pores. • The presence of residual solvent molecules adds significant complexity to the interpretation of NMR spectra. • The gas-phase method is superior for adsorbing TMPO as it eliminates interactions with residual solvent molecules. [ABSTRACT FROM AUTHOR]

The liquid-vapor-phase equilibrium properties of the previously developed TIP4P-Ew water model have been studied using thermodynamic integration free-energy simulation techniques in the temperature range of 274–400 K. We stress that free-energy results from simulations need to be corrected in order to be compared to the experiment. This is due to the fact that the thermodynamic end states accessible through simulations correspond to fictitious substances (classical rigid liquids and classical rigid ideal gases) while experiments operate on real substances (liquids and real gases, with quantum effects). After applying analytical corrections the vapor pressure curve obtained from simulated free-energy changes is in excellent agreement with the experimental vapor pressure curve. The boiling point of TIP4P-Ew water under ambient pressure is found to be at 370.3±1.9 K, about 7 K higher than the boiling point of TIP4P water (363.7±5.1 K; from simulations that employ finite range treatment of electrostatic and Lennard-Jones interactions). This is in contrast to the approximately +15 K by which the temperature of the density maximum and the melting temperature of TIP4P-Ew are shifted relative to TIP4P, indicating that the temperature range over which the liquid phase of TIP4P-Ew is stable is narrower than that of TIP4P and resembles more that of real water. The quality of the vapor pressure results highlights the success of TIP4P-Ew in describing the energetic and entropic aspects of intermolecular interactions in liquid water. [ABSTRACT FROM AUTHOR]

The electrical properties of Al2O3 as a gate dielectric in metal-oxide-semiconductor structures based on n- and p-type 4H-SiC grown by sublimation method have been investigated and compared to the properties of similar structures utilizing SiO2. The electrically active defects in the structures are studied by capacitance–voltage (C–V) and current–voltage (I–V) methods. The results show that the type as well as spatial and energy distributions of defects in Al2O3/SiC and SiO2/SiC samples are different. The structures with Al2O3 on p-type 4H-SiC demonstrate much better electrical characteristics than the p-type 4H-SiC/SiO2 structures. It is demonstrated that the conduction process in the former is governed by Fowler–Nordheim electron tunneling from the Al gate whereas in the latter the hole tunneling from SiC is the more probable process. This difference combined with the higher defect density in p-type SiC/SiO2 structures defines the higher leakage currents compared to the structures utilizing Al2O3. [ABSTRACT FROM AUTHOR]