H2O HCl Research Articles

A minimal model of potential energy surface for H2OHCl

AbstractIn this paper, we present a model of potential energy surface for the H2OHCl system, consisting in the exact transformation of quantum chemical input data related to a minimal number of significant configurations. Both molecules are assumed as rigid. The interaction potential is given by an expansion in real spherical harmonics depending on the distance between the two centers of mass of the molecules and on four angles that define their mutual orientation. The main target of this work is the construction of a model of potential energy surface that requires a limited number of single energy points, which is suitable for applications to classical and quantum molecular dynamics simulations, permitting interpolation and further implementation of different sets of input data.

Synthesis and redox reactions of amphiphilic metal(II) complexes of 5,10,15,20-tetraaryl-5,15-diazaporphyrinoids containing triethylene glycol or tetraethylene glycol units

In this paper, we report the first examples of amphiphilic metal(II) complexes of 5,10,15,20-tetraaryl-5,15-diazaporphyrinoids (M-TADAPs) containing triethylene glycol (TriEG) or tetraethylene glycol (TetEG) auxiliaries. A common dipyrrin precursor substituted with TriEG or TetEG groups underwent metal-templated cyclization with zinc(II), nickel(II), or copper(II) acetate to afford the corresponding TriEG- or TetEG-appended M-TADAPs (M = Zn, Ni, Cu) as air-stable 19[Formula: see text]-electron radical cations. These 19[Formula: see text]-electron M-TADAPs were reversibly interconvertible with 20[Formula: see text]-electron antiaromatic M-TADAPs and 18[Formula: see text]-electron aromatic M-TADAP dications by redox reactions. The newly prepared M-TADAPs were basically amphiphilic, but their water solubilities varied considerably depending on the charge of the diazaporphyrin (DAP) ring and the number of ethylene glycol units. The neutral 20[Formula: see text]-electron M-TADAPs were poorly soluble in water, whereas the 18[Formula: see text]-electron M-TADAP dications were soluble in water. Cyclic voltammetry of all M-TADAP derivatives revealed 20[Formula: see text]/19[Formula: see text]-electron and 19[Formula: see text]/18[Formula: see text]-electron redox couples in both CH2Cl2 and H2O with appropriate electrolytes. The addition of M[Formula: see text]X (M[Formula: see text] = Li, Na; X = Cl, OH) or HCl to aqueous solutions of the M-TADAPs highlighted their reactivities with anions and changes in pH. When treated with M[Formula: see text]X in H2O, the 19[Formula: see text]-electron M-TADAP radical cations underwent anion exchange but the 18[Formula: see text]-electron Zn-TADAP dications were reduced to the corresponding 19[Formula: see text]-electron species. Upon treatment with HCl in H2O, the 19[Formula: see text]-electron M-TADAP radical cations underwent one-electron oxidation of the DAP ring, and the resulting 18[Formula: see text]/19[Formula: see text]-electron abundance ratio increased with decreasing solution pH.

Consistent thermodynamic modeling of H2O–HCl–KOH–KCl between 200 K and 1,000 K

Over the last few decades, thermochemical databases for aqueous solutions and for high-temperature salt solutions have been developed separately from each other. This is largely due to the fact that the models used for the liquid phases are inconsistent. However, there is interest in highly concentrated aqueous solutions, as well as in the hydrolysis of salt melts, closing the gap between the two communities. Here, the liquid phase was consistently modeled, covering the complete composition space between H2O, HCl, KOH, and KCl at temperatures between 200 K and 1,000 K. Thermodynamic modeling of phase equilibria in the KCl–K2O–HCl–H2O reciprocal system was carried out using an associate solution model for the liquid phase, spanning from water to pure liquid acid and base, and liquid salt. Using the Calphad technique, the H2O–KCl, H2O–HCl, H2O–K2O, and KOH–KCl binary systems were critically assessed. While the model does not cover classical aqueous thermochemical properties (pH and osmotic coefficient), an excellent representation of phase diagrams and heat of reactions was achieved.

Thermochemical prediction of runaway energetic reactions involving organometallic (Al, In) and silane precursors in deposition tools

In the manufacturing of integrated circuits (ICs), many deposition systems use solid, liquid, and gaseous precursors that can form potentially hazardous by-products in the exhaust lines. To assess the likelihood of an energetic reaction taking place, Gibbs free energy minimization was used to examine the reactions between chemical precursors, such as trimethylaluminum, trimethylindium, silane, and silane derivatives with H2O, O3, and Cl2. For the trimethyl-metal precursors, CH4 is a major by-product in both the O3 and H2O environments, and CH4, HCl, and CCl4 are possible products in the Cl2 environment. For silanes, a small H2O to silane ratio leads predominantly to the formation of H2 and siloxane while a large H2O to silane ratio leads primarily to the formation of H2 and more H2O. In addition to depositing reaction by-products, unreacted precursors may also deposit on the interior surfaces of the exhaust system, narrowing the cross-sectional area of the pipes. These narrowed regions can become temperature, pressure, and concentration hot spots where energetic reactions are more likely to occur. Results from this analysis may be helpful in designing a safer downstream exhaust system that minimizes the risk of energetic events.

Ultrasonic Shaking of Glauconite Pellets with Diverse Reagents for a Comparison of Their K–Ar with Already Published Rb–Sr Results

A combined ultrasonic treatment, with de-ionized H2O, dilute HAc or dilute HCl, of three Mid-Miocene glauconite samples was applied to K–Ar date the different separates in order to compare the results with those obtained by the Rb–Sr method using the same three samples and that were analyzed strictly in the same way. Two aliquots yield opposite elemental and K–Ar trends, which suggests different initial mineral compositions for the various pellets. The K–Ar data of two untreated and leached L7 and L8 aliquots are almost within analytical uncertainty from 17.3 ± 0.6 Ma to 19.6 ± 0.7 Ma (2σ), while those of the third L10 sample are slightly higher at 22.1 ± 1.2 Ma (2σ). Comparatively, the earlier published Rb–Sr ages of the three untreated samples and of the leached aliquots gave similar data for the L7 aliquots by an isochron at 18.1 ± 3.1 (2σ) Ma and for the sample L8 by an isochron with an age of 19.6 ± 1.8 (2σ) Ma, while the untreated L10 aliquot yields a very high Rb–Sr date of 42.1 ± 1.6 (2σ) Ma. This untreated L10 glauconite fraction contains blödite, a Sr-rich carbonate that impacted the two isotopic systems differently. Generally, dilute HCl or HAc acids dissolve carbonates, sulfates, sulfites and oxides, while they do not affect the clay-type crystals such as glauconites. These soluble minerals can be identified indirectly, as here, by X-ray diffraction and the amounts of leached Na2O, CaO and Fe2O3 contents. Together with the leaching of some metallic trace elements, those of NaO confirm the leaching of metals and of blödite that are both hosted by the glauconite pellets. The occurrence of this Sr-enriched mineral explains the age differences of the non-treated aliquots and suggests a systematic leaching of any glauconite separate before isotope determination and, possibly, a comparison of the Rb–Sr and K–Ar results. Ultrasonic shaking appears appropriate for physical disaggregation of any contaminating grains that may remain hosted within the pellets, even after a preliminary H2O wash, which may dissolve and remove the soluble minerals but not the H2O-insoluble silicates. The K–Ar study completed here as a complement to a previous Rb–Sr study highlights, again, the importance of the preparation step in isotopic studies of glauconite-type and, by extension, of any clay material, as all occurring minerals can interfere in the final age determinations and, therefore, differently in the mineral assemblages. All those not in isotopic equilibrium need to be removed before analysis, including the soluble Sr or alkali-enriched ones.

COMPETITION BETWEEN METHANOL AND WATER MOLECULES UPON THE FORMATION AND SOLVATION OF IONS IN THE CH3OH–H2O–HCl SYSTEM

IR spectroscopy and density functional theory (B3LYP/6-31++G(d, p)) are used to study the competition between methanol and water molecules during the formation of (CH3(H)O∙∙∙H∙∙∙O(H)CH3)+, (CH3(H)O∙∙∙H∙∙∙OH2)+, and (H2O∙∙∙H∙∙∙OH2)+ ions with strong quasi-symmetrical H-bonds and their solvation in the CH3OH–H2O–HCl system. When water is added to a solution of HCl in methanol, H2O molecules substitute CH3OH molecules in (CH3(H)O∙∙∙H∙∙∙O(H)CH3)+ ions to form mixed disolvates. Conversely, when methanol is added to an aqueous solution of HCl, (H2O∙∙∙H∙∙∙OH2)+ ions are maintained and CH3OH molecules are involved in their solvation. Provided that the fractions of methanol and water are commensurate, the solutions contain simultaneously (CH3(H)O∙∙∙H∙∙∙OH2)+ and (H2O∙∙∙H∙∙∙OH2)+ ions. The ratio between their concentrations depends on the content of HCl in the system. It is shown that the energy of the hydrogen bond system per one dissociated HCl molecule is the main factor determining the structure of CH3OH–H2O–HCl solutions, in particular, the composition of proton disolvates.

Evaluation of nutritional requirements of medicinal fungus, Pyrofomes demidoffii under submerged fermentation

Abstract Pyrofomes demidoffii is a medicinal wood decay fungus that exhibit antimicrobial and also antioxidant properties. The aim of this study was to evaluate the optimal nutritional requirements for growth of P. demidoffii under submerged fermentation expressed in terms of mycelial dry weight. For this study, carbon, nitrogen, macro-mineral elements and vitamins sources were evaluated under submerged cultures using one-factor-at-a-time and in orthogonal design method. In one-factor-at-a-time analysis, soluble starch, yeast extract, MgSO4.7H2O and thiamine HCL produced the highest mycelial dry weight among carbon-, nitrogen-, macro-mineral element-sources and vitamins sources, respectively. In the orthogonal design method, maximum mycelial dry weight of 4.19 ± 0.03 g/L were produced under nutrient conditions of starch, 40 g/L; yeast extract, 3 g/L; MgSO4.7H2O, 0.5 g/L and thiamine HCl, 0.01 g/L. The magnitude order of the effect of all factors (R value) was in the order of soluble starch (1.75 g/L) > yeast extract (0.99 g/L) > thiamine HCl (0.87 g/L) > MgSO4.7H2O (0.51 g/L). The optimal mycelial dry weight could be produced at concentration of 40 g soluble starch, 3 g yeast extract, 0.01 g thiamine HCl and 0.75g MgSO4.7H2O in 1 L of distilled water. In conclusion, this study identified the optimal nutrient sources for the optimal growth of P. demidoffii in one-factor-at-a-time, and the optimum concentration in the orthogonal design. This is the first report on optimal nutritional requirements of the Ethiopian strain of P. demidoffii. The results of this study provide a basis for industrial fermentation and for various biotechnological uses.

Experimental Study of Amphibole Interaction with H2O–HCl Fluid at 650–750°C, 5–7 Kbar: Implications for High-Temperature Metasomatism of Metabasites

Interaction between amphibole and H2O–HCl fluid was experimentally studied in an internally heated pressure vessel (IHPV) at 650–800°C and 5–7 kbar. The stability of the anorthite–amphibole association was approved to be constrained at T = 650–800°C, (P = 5–7 kbar) within a range of HCl fugacity (fHCl) 50 100 µm) corundum and quartz crystals. Based on experimental data, it is demonstrated that interaction between metabasite with acidified fluid resulted in Ca, Fe, and no so much Mg removal from the metabasite (as inferred for rocks cropping out on Kii Island in the White Sea). The HCl fugacity in the metasomatizing fluid was approximately 50–200 bar at T = 650 – 800°C, P = 5–7 kbar. Rock depletion in bases led to that the residual matrix enriched in Al2O3 and SiO2, and this was favorable for the origin of corundum, on the one hand, and highly silicic rocks, like quartzite, on the other.

Environment of the Al3+ ion in Water–Acetone Solutions of Aluminum Chloride

Water–acetone solutions in the AlCl3–(CH3)2CO–H2O and AlCl3–(CH3)2CO–H2O–HCl systems were obtained and studied. In both cases, the solution separated into layers to form liquid fractions of lower and higher density. The IR spectra of the fractions were studied. In the light fraction, no AlCl3 was present, but hydrogen-bonded acetone–water complexes were detected. The spectra of the heavy fraction exhibited a broad band at ~3020–3040 cm–1 corresponding to the OH groups of water from aluminum hexahydrate. As the solvent is evaporated, the band narrows down, with its position being retained. The IR spectrum of the obtained solid becomes identical to the IR spectrum of the crystal hydrate AlCl3.(H2O)6. The structures and spectral and energetic parameters of Al(H2O) 6 3+ , Al(H2O) 6+12 3+ , Al((CH3)2CO) 6 3+ , Al((CH3)2CO) 4 3+ , and (CH3)2CO.H2O were calculated by the density functional theory method (B3LYP/6-31++G(d,p)). Relying on the results, an explanation was proposed for the experimentlly observed absence of acetone molecules in the Al3+ first coordination shell.

Resin-based dental sealants as a source of human exposure to bisphenol analogues, bisphenol A diglycidyl ether, and its derivatives

Although studies have examined leaching of bisphenol A (BPA) from dental sealants into saliva, occurrence of BPA, bisphenol A diglycidyl ether (BADGE), and their derivatives in dental sealants themselves has not been investigated. In this study, concentrations of eight bisphenol analogues (BPs), BADGE and its derivatives (BADGEs), including BADGE‧H2O, BADGE‧HCl, BADGE‧2H2O, BADGE‧2HCl, and BADGE‧H2O‧HCl, were determined in 70 dental sealants collected from the U.S. market. Of the 70 dental sealants analyzed, 65 contained at least one of the target chemicals measured. BADGE‧2H2O was the most abundant compound, found at concentrations of up to 1780µg/g. The geometric mean (GM) concentration of total BADGEs was 47.8µg/g, which was two to three orders of magnitude higher than that of total BPs (GM: 539ng/g). BPA was found in 46% of the sealants and BADGEs was found in 87% of the sealants analyzed. Majority of the dental sealants analyzed in this study were manufactured in the United States and Korea; no significant differences were observed in the concentrations of BPs and BADGEs between the two countries. An exposure assessment was made based on the concentrations of BPs and BADGEs measured in sealants and their application rates in dentistry. The worst-case exposure scenario with the highest measured concentration of total BPs and BADGEs and application on 8 teeth at 8mg each yielded an estimated daily intake (EDI) of 1670 and 5850ng/kg·bw/day for adults and children, respectively. Although the EDI is below the specific migration limit set by the European Food Safety Authority, dental sealants are a source of exposure to BPs and BADGEs, especially in children.

Synthesis and crystal structure of pyrroloquinoline quinol (PQQH2) and pyrroloquinoline quinone (PQQ).

Pyrroloquinoline quinone (PQQ) is a water-soluble quinone compound first identified as a cofactor of alcohol- and glucose-dehydrogenases (ADH and GDH) in bacteria. For example, in the process of ADH reaction, alcohol is oxidized to the corresponding aldehyde, and inversely PQQ is reduced to pyrroloquinoline quinol (PQQH2). PQQ and PQQH2 molecules play an important role as a cofactor in ADH and GDH reactions. However, crystal structure analysis has not been performed for PQQ and PQQH2. In the present study, the synthesis of PQQH2 powder crystals was performed under air, by utilizing vitamin C as a reducing agent. By reacting a trihydrate of disodium salt of PQQ (PQQNa2·3H2O) with excess vitamin C in H2O at 293 and 343 K, yellowish brown and black powder crystals of PQQH2 having different properties were obtained in high yield, respectively. The former was PQQH2 trihydrate (PQQH2·3H2O) and the latter was PQQH2 anhydrate (PQQH2). Furthermore, sodium-free red PQQ powder crystal (a monohydrate of PQQ, PQQ·H2O) was prepared by the reaction of PQQNa2·3H2O with HCl in H2O. Single crystals of PQQH2 and PQQ were prepared from Me2SO/CH3CN mixed solvent, and we have succeeded in the crystal structure analyses of PQQH2 and PQQ for the first time.

Surface chemical cleaning of the extended blue varied-doping Ga0.37Al0.63As photocathode

To improve the quantum efficiency of the extended blue varied-doping Ga0.37Al0.63As photocathode, different cleaning methods for oxide and carbon on the surface of the Ga0.37Al0.63As photocathode were investigated. The surface structure and atomic compositions of the Ga0.37Al0.63As photocathode were measured by X-ray photoelectron spectroscopy and Ar+ ion sputtering. After preparation and activation of the Ga0.37Al0.63As photocathode in an ultra-high vacuum system, the spectral response curves and quantum efficiency curves were measured, and then, curve fitting and analysis were performed. The experimental results showed that in regard to surface chemical cleaning of the Ga0.37Al0.63As samples, it was difficult to effectively remove the oxide with only the H2SO4:H2O2:H2O (4:1:100) solution, while carbon could not be removed with the HCl:H2O (1:3) solution alone. A two-step chemical cleaning method with the H2SO4:H2O2:H2O (4:1:100) solution and HCl:H2O (1:3) solution could effectively remove the oxide as well as the carbon. After cleaning, the quantum efficiency was increased from 18% to 27% at 532nm and the electron escape probability was increased from 0.51 to 0.71.

Etching Silicon with Aqueous Acidic Ozone Solutions: Reactivity Studies and Surface Investigations

Aqueous acidic ozone (O3)-containing solutions are increasingly used for silicon treatment in photovoltaic and semiconductor industries. We studied the behavior of aqueous hydrofluoric acid (HF)-containing solutions (i.e., HF–O3, HF–H2SO4–O3, and HF–HCl–O3 mixtures) toward boron-doped solar-grade (100) silicon wafers. The solubility of O3 and etching rates at 20 °C were investigated. The mixtures were analyzed for the potential oxidizing species by UV–vis and Raman spectroscopy. Concentrations of O3 (aq), O3 (g), and Cl2 (aq) were determined by titrimetric volumetric analysis. F–, Cl–, and SO42– ion contents were determined by ion chromatography. Model experiments were performed to investigate the oxidation of H-terminated silicon surfaces by H2O–O2, H2O–O3, H2O–H2SO4–O3, and H2O–HCl–O3 mixtures. The oxidation was monitored by diffuse reflection infrared Fourier transformation (DRIFT) spectroscopy. The resulting surfaces were examined by scanning electron microscopy (SEM) and X-ray photoelectron spectrosc...

Water‐Soluble Platinum(II) Complexes Featuring 2‐Alkyl‐2H‐tetrazol‐5‐ylacetic Acids: Synthesis, Characterization, and Antiproliferative Activity

2‐R‐2H‐Tetrazol‐5‐ylacetic acids (abbreviated as 2‐R‐taa; R = Me, iPr, tBu) react with K2[PtCl4] in 1 m HCl in H2O at r.t. furnishing trans‐platinum(II) complexes trans‐[PtCl2(2‐R‐taa)2] (1–3), whereas cis‐isomeric species cis‐[PtCl2(2‐R‐taa)2] (R = iPr, 4; tBu, 5) are isolated at lower temperature (4–6 °C). In the presence of EtOH in the reaction mixture, esterification of the tetrazol‐5‐ylacetoxy group of 2‐tBu‐taa leads to trans‐[PtCl2(ethyl 2‐tert‐butyl‐2H‐tetrazol‐5‐ylacetate)2] (6). Complexes 1–6 were characterized by elemental analyses (CHN), HRESI+‐MS, 1H, 13C{1H}, 195Pt{1H} NMR and IR spectroscopy, differential scanning calorimetry/thermogravimetry (DSC/TG), and X‐ray diffraction (for 1·H2O, 2, 3·2H2O, 4, 5·2H2O, and 6). The generation of the tetrazole‐based complexes in solution (1 m DCl in D2O, 25 °C) was studied by 1H NMR spectroscopy and HPLC‐MS. The obtained data indicate the initial formation of anionic [PtCl3(2‐R‐taa)]– complexes that are subsequently converted into disubstituted isomeric platinum(II) species cis‐ and trans‐[PtCl2(2‐R‐taa)2]. By contrast to cis‐ and trans‐[PtCl2(2‐R‐taa)2] that were inactive in two human cancer models in vitro (IC50 > 100 µm), complex 6 demonstrated noticeable antiproliferative effects in HT‐29 colon and MCF‐7 breast carcinoma cell lines with IC50 values of 14.2 ± 1.1 and 5.8 ± 1.2 µm, respectively.

Determination of flavonoids as complexes with Al3+ in microemulsion media by HPLC method with fluorescence detection

ABSTRACTThe scheme of postcolumn complexation reaction of flavonoids with aluminum (III) ions in various microemulsion media followed by fluorimetric detection is proposed. It is shown that fluorescence intensity of such complexes is five, three, and three times higher for quercetin, isorhamnetin, and kaempferol, respectively, when compared with the complexes obtained by dissolving flavonoids in MeCN/0.1 M HCl (30/70) and AlCl3 in H2O. The prospect of using microemulsions for quantitative quercetin extraction from plant raw material is demonstrated. Recovery of quercetin from onion peel is 98% with detection limits being 100, 45, and 15 ng/L for quercetin, isorhamnetin, and kaempferol, respectively. Quercetin content in three types of onion peel is determined. This content is found to be 34 ± 3 and 5 ± 1 mg/g for yellow and purple onion peel, respectively, while the content in white onion peel is below the detection limit.

Optimization of the CeO2/CeCl3 cycle by cerium IV oxide reductive dissolution catalysis

While thermochemical cycles can be a way to produce hydrogen, physiochemical studies show that implementing them is often difficult for reactivity reasons. Most of the cycles actually involve solid–gas type systems with limited reactivity due to interface passivation processes. To overcome this difficulty, studies have shown that using the CeO2/CeCl3 pair, in which the cerium undergoes a reversible oxidation–reduction cycle, has enormous potential since it may partially be carried out in aqueous phase by reductive dissolution from cerium oxides (IV) to cerium chloride (III).If the first reaction of the cycle is well known for industrial application, its second and its third reaction still need some investigation. Thus, this article primarily describes the work done on the second reaction to assess the possibility of carrying out cerium reduction in aqueous phase. The extremely positive results have highlighted the possibility of achieving 100% reaction efficiency in systems catalyzed by fluoride ions. Conducting the reaction with in-line distillation of the excess water also helps significantly reduce reaction time which offers good potential for the next stage. A ratio of 8 ml of a 20 w% HCl solution per gram of CeO2 containing 6w% of CaF2 leads to ensure a total reaction in a few minutes at 108.6 °C (boiling temperature of the H2O–HCl azeotrope).The work presented herein also describes a brief feasibility study for the third reaction cycle which could be carried out by spraying the solution from the second reaction, in a hot column whose temperature will be determined by further work. These results have allowed upgrading the first flowsheet proposed in a previous publication.

H<sub>2</sub>O and HCl trace gas kinetics on crystalline HCl hydrates and amorphous HCl / H<sub>2</sub>O in the range 170 to 205 K: the HCl / H<sub>2</sub>O phase diagram revisited

Abstract. In this laboratory study, H2O ice films of 1 to 2 μm thickness have been used as surrogates for ice particles at atmospherically relevant conditions in a stirred flow reactor (SFR) to measure the kinetics of evaporation and condensation of HCl and H2O on crystalline and amorphous HCl hydrates. A multidiagnostic approach has been employed using Fourier transform infrared spectroscopy (FTIR) absorption in transmission to monitor the condensed phase and residual gas mass spectrometry (MS) for the gas phase. An average stoichiometric ratio of H2O : HCl = 5.8 ± 0.7 has been measured for HCl · 6H2O, and a mass balance ratio between HCl adsorbed onto ice and the quantity of HCl measured using FTIR absorption (Nin – Nesc – Nads) / NFTIR = 1.18 ± 0.12 has been obtained. The rate of evaporation Rev(HCl) for crystalline HCl hexahydrate (HCl · 6H2O) films and amorphous HCl / H2O mixtures has been found to be lower by a factor of 10 to 250 compared to Rev(H2O) in the overlapping temperature range 175 to 190 K. Variations of the accommodation coefficient α(HCl) on pure HCl · 6H2O up to a factor of 10 at nominally identical conditions have been observed. The kinetics (α, Rev) are thermochemically consistent with the corresponding equilibrium vapour pressure. In addition, we propose an extension of the HCl / H2O phase diagram of crystalline HCl · 6H2O based on the analysis of deconvoluted FTIR spectra of samples outside its known existence area. A brief evaluation of the atmospheric importance of both condensed phases – amorphous HCl / H2O and crystalline HCl · 6H2O – is performed in favour of the amorphous phase.

Texture-etched broad surface features of double-layered ZnO:Al transparent conductive films for high haze values

A multi-step chemical wet-etching method, with a process of ZnO:Al (AZO) deposition, NH3⋅H2O etching, AZO re-deposition and HCl re-etching, is developed to obtain a wide range distribution of texture features for improving the light trapping. The first mild step with a NH3⋅H2O etching process (for 4min) results in tiny craters with a lateral feature size of 100–400nm and root mean square (RMS) roughness of 34.5nm, which provides an effective light trapping for the short wavelength. The second HCl etching (for 15s) aims at texturing strong pits with ∼1.5μm feature size and ∼75nm RMS, which leads to enhanced light trapping in the long wavelength. The diffuse transmittance increases from 9.0% to 51.6% due to the enhanced light scattering by the double-layered texture with the NH3⋅H2O and HCl etching processes. The corresponding highest haze value of 59.6% is obtained compared to that of 6.8% at 550nm due to the re-etching process for the NH3⋅H2O-etched sample. This multi-step method will lead to a broad surface feature distribution of 100–1500nm, where the electrical properties remain a slight change. Such good double texture surfaces prepared by the novel etching method promote the potential application of AZO films in thin film solar cells.

The metastable HCl · 6H<sub>2</sub>O phase – IR spectroscopy, phase transitions and kinetic/thermodynamic properties in the range 170–205 K

Abstract. In this laboratory study a multidiagnostic experimental approach including Fourier transform infrared (FTIR) absorption of 1 to 2 μm thick polycrystalline ice films, residual gas mass spectrometry (MS) and total pressure measurement were employed. Both amorphous HCl–H2O and crystalline HCl hexahydrate (HCl · 6H2O) have been investigated. After controlled doping with HCl and evaporation of excess H2O from the ice film, transmission FTIR of pure HCl · 6H2O films and use of calibrated mass spectrometry enabled the measurement of differential (peak) IR cross sections at several mid-IR frequencies, for example σ = (6.5 ± 1.9) × 10−19 cm2 molec−1 at 1635 cm−1. Two types of kinetic experiments on pure HCl · 6H2O have been performed under SFR conditions: (a) evaporation of pure HCl · 6H2O over a narrow T range after evaporation of excess H2O, and (b) observation of the phase transition from crystalline HCl · 6H2O to amorphous HCl–H2O under H2O-rich conditions at increasing T. The temperature dependence of the zero-order evaporation flux of HCl in pure HCl · 6H2O led to logJev molec cm−2 s−1 = (36.34 ± 3.20) – (80 810 ± 5800)/2.303 RT with R = 8.314 JK−1 mol−1, which turned out to be rate-limiting for evaporation. HCl · 6H2O has a significant intrinsic kinetic barrier to HCl evaporation of 15.1 kJ mol−1 in excess of the HCl sublimation enthalpy of 65.8 kJ mol−1 at 200 K but is kinetically unstable (metastable) at T ≥ 173 K. The atmospheric importance of HCl · 6H2O is questioned in view of its large nucleation barrier and its dependence on T and P(HCl) compared to the amorphous HCl–H2O phase at upper tropospheric–lower stratospheric (UT/LS) conditions.

An experimental study of the transport of gold through hydration of AuCl in aqueous vapour and vapour-like fluids

Gold solubility and speciation in low density H2O–HCl vapour were investigated experimentally at temperatures between 300 and 450°C, and pressures up to 366bar using batch-type titanium autoclaves. Concentrations of total dissolved gold in the experimental condensates ranged from 0.9ppb at 300°C and 48bar to 4.6ppm at 400°C and 297bar. The hydrated gold monochloride species (AuCl(H2O)y) is the dominant gold species under the experimental conditions. Gold solubility increases with increasing water vapour pressure and can be expressed by the reaction,Aus+xHClg+yH2Og=AuClxH2Oy+x/2H2,gKs,yThe hydration number (y) increases with increasing pressure, thereby indicating that solvation by H2O molecules in the gas-phase is analogous to that in liquid-like fluids. Results of extrapolation of the data using a linear relationship of logKs,y with reciprocal temperature compare well with published experimental data for the solubility of gold at 1000°C in dilute HCl-bearing water vapour. At high water vapour pressure, the solubility of gold in an aqueous vapour with an HCl fugacity of 0.1bar is similar to that in a vapour with approximately 50bar H2S, in which AuS is the dominant gaseous gold species. This indicates that hydrated gold monochloride species may play an important role in magmatic–hydrothermal systems dominated by low density aqueous fluids with high HCl concentrations. Modelling of the cooling and decompression of HCl-bearing intermediate-density (0.35gcm−3) aqueous fluids shows that gold solubility reaches a maximum of 253ppm at 500°C. In fluids with densities of 0.20 and 0.10gcm−3 the corresponding solubility maxima are reached at ∼400°C, and are of 14.8 and 0.49ppm, respectively.