Search

New particle formation (NPF) substantially affects the global radiation balance and climate. Iodic acid (IA) is a key marine NPF driver that recently has also been detected inland. However, its impact on continental particle nucleation remains unclear. Here, we provide molecular-level evidence that IA greatly facilitates clustering of two typical land-based nucleating precursors: dimethylamine (DMA) and sulfuric acid (SA), thereby enhancing particle nucleation. Incorporating this mechanism into an atmospheric chemical transport model, we show that IA-induced enhancement could realize an increase of over 20% in the SA-DMA nucleation rate in iodine-rich regions of China. With declining anthropogenic pollution driven by carbon neutrality and clean air policies in China, IA could enhance nucleation rates by 1.5 to 50 times by 2060. Our results demonstrate the overlooked key role of IA in continental NPF nucleation and highlight the necessity for considering synergistic SA-IA-DMA nucleation in atmospheric modeling for correct representation of the climatic impacts of aerosols. [ABSTRACT FROM AUTHOR]

Abstract—Based on regular porous polymeric membranes, the synthesis of metal and dielectric spearhead structures with given morphological characteristics was carried out. Copper structures with the ~1 μm height and dielectric spearhead microstructures made from iodic acid with the 12 μm height and 1 μm diameter were obtained. The possibility is discussed of using such optical elements to solve the problems of increasing the efficiency of IR radiation detection, signal amplification and conversion to visible and near-infrared ranges. [ABSTRACT FROM AUTHOR]

Iodic acid (IA), the key driver of marine aerosols, is widely detected within the gas and particle phases in the marine boundary layer (MBL) and even the free troposphere (FT). Although atmospheric bases like dimethylamine (DMA) and ammonia (NH 3 ) can enhance IA particles formation, their different efficiencies and spatial distributions make the dominant base-stabilization mechanisms of forming IA particles unclear. Herein, we investigated the IA-DMA-NH 3 nucleation system through quantum chemical calculations at the DLPNO-CCSD(T)/aug-cc-pVTZ(-PP)//ωB97X-D/6-311++G(3df,3pd) + aug-cc-pVTZ-PP level of theory and cluster dynamics simulations. We provide molecular-level evidence that DMA and NH 3 can jointly stabilize the IA clusters. The formation rates of IA clusters initially decline before rising from the MBL to the FT, owing to variations in mechanism. In the MBL, IA-DMA nucleation predominates, while the contribution of IA-DMA-NH 3 synergistic nucleation cannot be overlooked in polar and NH 3 -polluted regions. In the lower FT, IA-DMA-NH 3 nucleation prevails, whereas in the upper FT, IA-NH 3 nucleation dominates. The efficiency of IA-DMA-NH 3 nucleation is comparable to that of IA-iodous acid nucleation in the MBL and sulfuric acid-NH 3 nucleation in the FT. Hence, the IA-DMA-NH 3 mechanism holds promise for revealing the missing sources of tropospheric IA particles.

New particle formation (NPF) substantially affects the global radiation balance and climate. Iodic acid (IA) is a key marine NPF driver that recently has also been detected inland. However, its impact on continental particle nucleation remains unclear. Here, we provide molecular-level evidence that IA greatly facilitates clustering of two typical land-based nucleating precursors: dimethylamine (DMA) and sulfuric acid (SA), thereby enhancing particle nucleation. Incorporating this mechanism into an atmospheric chemical transport model, we show that IA-induced enhancement could realize an increase of over 20% in the SA-DMA nucleation rate in iodine-rich regions of China. With declining anthropogenic pollution driven by carbon neutrality and clean air policies in China, IA could enhance nucleation rates by 1.5 to 50 times by 2060. Our results demonstrate the overlooked key role of IA in continental NPF nucleation and highlight the necessity for considering synergistic SA-IA-DMA nucleation in atmospheric modeling for correct representation of the climatic impacts of aerosols., Competing Interests: Competing interests statement:The authors declare no competing interest.

Gaseous sulfur compounds are emitted from many facilities, such as wastewater facilities or biomass power plants, due to the decay of organic compounds. Gaseous dimethyl sulfide removal by ozone catalytic oxidation was investigated in this study. A Vacuum-Ultra-Violet (VUV) xenon excimer lamp of 172 nm was used for ozone generation without NOx generation, and activated carbon impregnated with iodic acid and H2SO4 was utilized as a catalyst. Performance assessment of dimethyl sulfide removal ability was carried out by a dynamic adsorption experiment. Empty-Bed-Contact-Time (EBCT), superficial velocity, concentration of dimethyl sulfide, temperature and humidity were set at 0.48 s, 0.15 m/s, 3.0 ppm, 25 °C and 45%, respectively. Without ozone addition, the adsorption capacity of impregnated activated carbon was 0.01 kg/kg. When ozone of 7.5 ppm was added, the adsorption capacity of impregnated activated carbon was increased to 0.15 kg/kg. Methane sulfonic acid, a reaction product of dimethyl sulfide and ozone, was detected from the activated carbon. The results suggest that the VUV and activated carbon impregnated with iodic acid and H2SO4 are workable for ozone catalytic oxidation for gas treatments. [ABSTRACT FROM AUTHOR]

Analytic Rayleigh wave speed formula in nonlinear orthotropic medium is determined. Speed of Rayleigh waves in iodic acid, a specimen of non-linear orthotropic materials, is calculated and is compared with that of the speed in linear orthotropic iodic acid. In linear iodic acid, three distinct Rayleigh waves propagate with speeds 53.44 km/s, 80.94 km/s, and 125.37 km/s, respectively. While, in nonlinear iodic acid these three waves become coincident and only one Rayleigh wave seem to propagate with velocity 63.68 km/s. [ABSTRACT FROM AUTHOR]

During summer, the Southern Ocean is largely unaffected by anthropogenic emissions, which makes this region an ideal place to investigate marine natural aerosol sources and processes. A better understanding of natural aerosol is key to constrain the preindustrial aerosol state and reduce the aerosol radiative forcing uncertainty in global climate models. We report the concentrations of gaseous sulfuric acid, iodic acid, and methanesulfonic acid (MSA) together with a characterization of new particle formation (NPF) events over a large stretch of the Southern Ocean. Measurements were conducted on board the Russian icebreaker Akademik Tryoshnikov from January to March 2017. Iodic acid is characterized by a particular diurnal cycle with reduced concentration around noon, suggesting a lower formation yield when solar irradiance is higher. Gaseous MSA does not have a diurnal cycle and measured concentrations in gas and condensed phase are compatible with this species being primarily produced via heterogeneous oxidation of dimethyl sulfide and subsequent partitioning into the gas phase. We also found that NPF in the boundary layer is mainly driven by sulfuric acid but it occurred very rarely over the vast geographical area probed and did not contribute to the cloud condensation nuclei budget in a directly observable manner. Despite the near absence of NPF events in the boundary layer, Aitken mode particles were frequently measured, supporting the hypothesis of a free tropospheric source. Iodic acid and MSA were not found to participate in nucleation, however, MSA may contribute to aerosol growth via heterogeneous formation in the aqueous phase. Key Points: Production of methanesulfonic acid occurred predominantly in the condensed phase, followed by enhanced volatilization at lower relative humidityThe observed new particle formation events were probably driven by sulfuric acid and the environmental conditions (mainly temperature and condensation sink)Boundary layer new particle formation over the Southern Ocean in summer occurred very sporadically and does not contribute to the cloud condensation nuclei budget [ABSTRACT FROM AUTHOR]

New particle formation via the ion-mediated sulfuric acid and ammonia molecular clustering mechanism remains the most widely observed and experimentally verified pathway. Recent laboratory and molecular level observations indicate iodine-driven nucleation as a potentially important source of new particles, especially in coastal areas. In this study, we assess the role of iodine species in particle formation using the best available molecular thermochemistry data and coupled to a detailed 1-d column model which is run along air mass trajectories over the Southern Ocean and the coast of Antarctica. In the air masses traversing the open ocean, ion-mediated SA-NH 3 clustering appears insufficient to explain the observed particle size distribution, wherein the simulated Aitken mode is lacking. Including the iodine-assisted particle formation improves the modeled Aitken mode representation with an increase in the number of freshly formed particles. This implies that more particles survive and grow to Aitken mode sizes via condensation of gaseous precursors and heterogeneous reactions. Under certain meteorological conditions, iodine-assisted particle formation can increase cloud condensation nuclei concentrations by 20%-100%.

Gaseous sulfur compounds are emitted from many facilities, such as wastewater facilities or biomass power plants, due to the decay of organic compounds. Gaseous dimethyl sulfide removal by ozone catalytic oxidation was investigated in this study. A Vacuum-Ultra-Violet (VUV) xenon excimer lamp of 172 nm was used for ozone generation without NOx generation, and activated carbon impregnated with iodic acid and H2SO4 was utilized as a catalyst. Performance assessment of dimethyl sulfide removal ability was carried out by a dynamic adsorption experiment. Empty-Bed-Contact-Time (EBCT), superficial velocity, concentration of dimethyl sulfide, temperature and humidity were set at 0.48 s, 0.15 m/s, 3.0 ppm, 25 °C and 45%, respectively. Without ozone addition, the adsorption capacity of impregnated activated carbon was 0.01 kg/kg. When ozone of 7.5 ppm was added, the adsorption capacity of impregnated activated carbon was increased to 0.15 kg/kg. Methane sulfonic acid, a reaction product of dimethyl sulfide and ozone, was detected from the activated carbon. The results suggest that the VUV and activated carbon impregnated with iodic acid and H2SO4 are workable for ozone catalytic oxidation for gas treatments.

Iodic acid (HIO3) is known to form aerosol particles in coastal marine regions, but predicted nucleation and growth rates are lacking. Using the CERN CLOUD (Cosmics Leaving Outdoor Droplets) chamber, we find that the nucleation rates of HIO3 particles are rapid, even exceeding sulfuric acid–ammonia rates under similar conditions. We also find that ion-induced nucleation involves IO3 − and the sequential addition of HIO3 and that it proceeds at the kinetic limit below +10°C. In contrast, neutral nucleation involves the repeated sequential addition of iodous acid (HIO2) followed by HIO3, showing that HIO2 plays a key stabilizing role. Freshly formed particles are composed almost entirely of HIO3, which drives rapid particle growth at the kinetic limit. Our measurements indicate that iodine oxoacid particle formation can compete with sulfuric acid in pristine regions of the atmosphere. [ABSTRACT FROM AUTHOR]

Iodine oxoacids (HIO 3 and HIO 2 )-driven nucleation has been suggested to efficiently contribute to new particle formation (NPF) in marine atmospheres. Abundant atmospheric nucleation precursors may further enhance HIO 3 -HIO 2 -driven nucleation through various multicomponent nucleation mechanisms. However, the specific enhancing potential (EP) of different precursors remains largely unknown. Herein, the EP-based screening model of precursors and enhancing mechanism of the precursor with the highest EP on HIO 3 -HIO 2 nucleation were investigated. The formation free energies (Δ G ), as critical parameters for evaluating EP, were calculated for the dimers of 63 selected precursors with HIO 2 . Based on the Δ G values, (1) a quantitative structure-activity relationship model was developed for evaluating Δ G of other precursors and (2) atmospheric concentrations of 63 (precursor) 1 (HIO 2 ) 1 dimer clusters were assessed to identify the precursors with the highest EP for HIO 3 -HIO 2 -driven nucleation by combining with earlier results for the nucleation with HIO 3 as the partner. Methanesulfonic acid (MSA) was found to be one of the precursors with the highest EP. Finally, we found that MSA can effectively enhance HIO 3 -HIO 2 nucleation at atmospheric conditions by studying larger MSA-HIO 3 -HIO 2 clusters. These results augment our current understanding of HIO 3 -HIO 2 and MSA-driven nucleation and may suggest a larger impact of HIO 2 in atmospheric aerosol nucleation.

Several new electronic states in HI have been identified from resonance-enhanced multiphoton ionization (REMPI) spectra in the 69 600–73 600 cm-1 region. These results have been combined with previously unpublished single-photon absorption data and, in selected wavelength regions, with REMPI spectra of DI to provide a more complete description of the excited electronic structure of HI up to ∼9.2 eV above the ground state. © 1995 American Institute of Physics. [ABSTRACT FROM AUTHOR]

In this study, the production of particulate films of iodine (V) oxides is investigated. The influence that sonication and solvation of suspended particles in various alcohol/ketone/ester solvents have on the physical structure of spin or drop cast films is examined in detail with electron microscopy, powder x-ray diffraction, and UV-visible absorption spectroscopy. Results indicate that sonicating iodine oxides in alcohol mixtures containing trace amounts of water decreases deposited particle sizes and produces a more uniform film morphology. UV-visible spectra of the pre-cast suspensions reveal that for some solvents, the iodine oxide oxidizes the solvent, producing I2 and lowering the pH of the suspension. Characterizing the crystals within the cast films reveal their composition to be primarily HI3O8, their orientations to exhibit a preferential orientation, and their growth to be primarily along the ac-plane of the crystal, enhanced at higher spin rates. Spin-coating at lower spin rates produces laminate-like particulate films versus higher density, one-piece films of stacked particles produced by drop casting. The particle morphology in these films consists of a combination of rods, plates, cubes, and rhombohedra structure.

Iodine oxides are of interest as biocidal components in energetic application such as thermites due to their high energy release and biocidal agent delivery. In this study, various iodine oxides/iodic acids, including I 2 O 5 , HI 3 O 8 and HIO 3 , were employed as oxidizers in thermite systems. Their decomposition behaviors were studied using a home-made time resolved temperature-jump/time-of-flight mass spectrometer (T-Jump/TOFMS), which identified a single step decomposition for all oxides at high heating rates (∼10 5  K/s). In addition, both nano-aluminum (nAl, ∼80 nm) and nano-tantalum (nTa, <50 nm) were adopted as the fuel in order to fully understand how iodine containing oxidizers react with the fuel during ignition. The ignition and reaction process of nAl-based and nTa-based thermites were characterized with T-Jump/TOFMS, and their combustion properties were evaluated in a constant-volume combustion cell and compared to a traditional thermite system (nAl/CuO). The ignition temperatures of nAl-based thermites using these oxidizers were all very close to the melting point of aluminum (∼660 °C), which suggests that the mobility of the aluminum core dominats the ignition/reaction and the gaseous oxygen released from the decomposition of the oxidizer does not participate in the ignition until the molten aluminum is available. Unlike nAl-based thermites, the ignition temperatures of nTa-based thermites are lower than the oxygen release temperatures from the corresponding bare oxidizers. All nTa-based thermites ignited prior to the release of gas phase oxygen. In this case, a condensed phase reaction mechanism is proposed to dominate the ignition process. Moreover, combustion cell tests results show that nAl/a-HI 3 O 8 has the highest pressurization rate and peak pressure and shortest burn time, and since it also has an iodine content of ∼75% as high as I 2 O 5 on a per mass basis, this material may be a very promising candidate in biocidal application. [ABSTRACT FROM AUTHOR]

In iodine-sulfur (I-S) thermo-chemical process for hydrogen production, Bunsen reaction is studied to identify the role of different operating conditions on purity of Bunsen reaction product phases. The focus of this work is to find out the level of contamination in each of the Bunsen reaction product phases. Hydroiodic acid and iodine are contaminants in sulfuric acid phase and sulfuric acid is contaminant in hydroiodic acid phase. Enhancing the level of purity in two product phases will reduce the burden on purification steps in downstream of I-S process. Bunsen reaction has been studied in continuous co-current reactor made of tantalum in the range of 50–75 °C, 2–6 bar (g) with HIx (mixture of hydroiodic acid, water and iodine) flow rate of 0.8 l/h - 3.3 l/h, sulfur dioxide 0.06 g/s – 0.24 g/s & oxygen 0.008 g/s −0.016 g/s. At 4 bar (g), 70 °C with HIx and SO 2 flow rates of 1.8 l/h and 0.24 g/s respectively, purity of sulfuric acid phase is maximum i.e. 99.85 mol percent. At 4 bar (g), 60 °C with HIx and SO 2 flow rates of 1.5 l/h and 0.12 g/s respectively, purity in HIx phase is maximum i.e. 99.66 mol percent. [ABSTRACT FROM AUTHOR]

A new polymorph of iodic acid, δ-HIO3, synthesized via aerosol spray pyrolysis was characterized with powder X-ray diffraction and its crystal structure was solved. We find that a previously misidentified phase of I4O9 hydrate is in fact a new polymorph of HIO3, which crystalizes in the orthorhombic space group P212121. [ABSTRACT FROM PUBLISHER]

Anisotropic acousto-optic diffraction in biaxial crystal of alpha-iodic acid has been studied in the case in which the wave vector of the ultrasound is almost orthogonal to one of the optical axes and the directions of incident and diffracted light beams are close to the optical axis. It is shown that, owing to the complex form of wave surfaces in the field of optical axes of a biaxial crystal, the considered variant of acousto-optic interaction is very sensitive to changes in the direction of the wave vector of the ultrasound that imposes special requirements to accuracy of manufacturing of acousto-optic devices. [ABSTRACT FROM AUTHOR]

Non linear optical single crystals of l-lysine-iodic acid (LLI) of dimensions upto 24 × 14 × 5 mm have been grown successfully by slow evaporation technique from aqueous solution. The crystal structure of the grown material was solved by single crystal X-ray diffraction analysis and it was found that the LLI crystal belongs to monocinic system with space group P2. Functional groups of the grown crystal were identified by Fourier Transform Infrared (FTIR) spectral analysis. The UV-Vis spectral analysis was carried out to measure the transparent range of the LLI crystal which is nearly 85% and the band gap energy is found to be 5.51 eV. Thermal stability and decomposition temperature of LLI crystal was found by means of TGA and DTA analyses. The mechanical behavior of the grown crystal has been employed using Vicker's micro hardness technique. The Second Harmonic Generation (SHG) efficiency of the crystal was investigated and it was found to be 3.2 times of KDP. The particle size dependent SHG studies of LLI crystals were performed using Nd:YAG laser. The laser damage threshold value of LLI crystal is found to be 8.54 GW/cm. Dielectric study indicates the reasonable dielectric constant and low dielectric loss of LLI crystal which are essential properties to develop optoelectronic devices. The ac and dc electrical conductivity measurements were carried out at various temperatures. Photoconductivity study exhibits the negative photoconductivity nature of the LLI crystal and the results are discussed for the first time. [ABSTRACT FROM AUTHOR]

Iodic acid (IA) has recently been recognized as a key driver for new particle formation (NPF) in marine atmospheres. However, the knowledge of which atmospheric vapors can enhance IA-induced NPF remains limited. The unique halogen bond (XB)-forming capacity of IA makes it difficult to evaluate the enhancing potential (EP) of target compounds on IA-induced NPF based on widely studied sulfuric acid systems. Herein, we employed a three-step procedure to evaluate the EP of potential atmospheric nucleation precursors on IA-induced NPF. First, we evaluated the EP of 63 precursors by simulating the formation free energies (Δ G ) of the IA-containing dimer clusters. Among all dimer clusters, 44 contained XBs, demonstrating that XBs are frequently formed. Based on the calculated Δ G values, a quantitative structure-activity relationship model was developed for evaluating the EP of other precursors. Second, amines and O/S-atom-containing acids were found to have high EP, with diethylamine (DEA) yielding the highest potential to enhance IA-induced nucleation by combining both the calculated Δ G and atmospheric concentration of considered 63 precursors. Finally, by studying larger (IA) 1-3 (DEA) 1-3 clusters, we found that the IA-DEA system with merely 0.1 ppt (2.5×10 6 cm -3 ) DEA yields comparable nucleation rates to that of the IA-iodous acid system.

The Ritter-type amination of a tertiary C–H bond using iodic acid (HIO3) as an oxidant, in the presence of N-hydroxyphthalimide (NHPI) is reported. This operationally simple method is conducted under metal-free conditions, is scalable, and efficiently provides valuable α-tertiary amine derivatives. [ABSTRACT FROM AUTHOR]

Various primary and secondary benzylic alcohols were efficiently oxidized to aromatic aldehydes and aromatic ketones with iodic acid in DMF at 60 °C for 2 h and with iodic acid in the presence of TEMPO (5 mol %) in DMF at room temperature, respectively. The former method was effective for the oxidation of sterically hindered alcohols at 60 °C and the latter method was effective for the oxidation of less sterically hindered alcohols at room temperature. [ABSTRACT FROM AUTHOR]

The structures, energetics, and thermodynamic properties of HIO 3 isomers (HOOOI, HOOIO, HOIO 2 , and HIO 3 ) have been computed using CCSD(T)/CBS theoretical method. The spin orbit corrections (SOC) have also been evaluated for the each iodine-containing molecule. The SOC value decreases as the iodine valence increases within the molecule. The results revealed that HOIO 2 was the most stable form and that HOOOI was the next most stable isomer. The standard enthalpies of formation at 298 K have been derived from IO + HO 2 and OH + OIO dissociation pathways. At the CCSD(T)/CBS level on B3LYP geometries, the recommended Δ f H ° 298K is (−95.4 ± 0.3) kJ mol −1 for HOIO 2 , and its computed S ° 298K and C p (300 K) values are respectively 339.12 and 75.28 J mol −1 K −1 . Further, monohydrated and dihydrated complexes of iodic acid have been investigated using DFT and wavefunction methods. Three and six mono- and di-hydrated complexes, respectively, have been identified. The hydrogen bonded complexes (HOIO 2 _1wa and HOIO 2 _2wa) are the lowest lying structures. The thermodynamics of dihydrates have been calculated from the total hydration of iodic acid (HOIO 2 + 2H 2 O). Mono- and di-hydration of iodic acid is a favored process at tropospheric and ambient conditions with the formation of HOIO 2 _1wa and HOIO 2 _2wa at T ⩽ 310 K. The positive Gibbs free energies at high temperatures indicate that gas-phase iodic acid would not be present in a hydrated form inside the nuclear containment building of a pressurized water reactor. [ABSTRACT FROM AUTHOR]

Iodine pentoxide (I 2 O 5 ) is typically synthesized by dehydration of iodic acid such that the produced material inherently includes hydrated iodic acid species that facilitate further water absorption when exposed to ambient environments. This is a detrimental property for I 2 O 5 powder used in energetic systems. A dry-approach for synthesizing I 2 O 5 with either crystalline (nano C I 2 O 5 ) or amorphous (nano A I 2 O 5 ) structure was used for this study and compared to the commercially available material. This synthesis approach enabled isolation of the microstructure as a variable to better understand water absorption behavior of I 2 O 5 and associated reactivity. Material characterization included BET, SEM, TEM, and XRD as well as equilibrium analyses using DSC and TGA along with flame speeds. Results show that nano C I 2 O 5 reacts less with atmospheric water and has a more anhydrous behavior than the crystalline I 2 O 5 powder commercially available. The nano A I 2 O 5 also produced a distinct pre-ignition reaction (PIR) and evidence for smaller PIRs are shown for all mixtures of Al with I 2 O 5 . These properties along with increased specific surface area of the nano C I 2 O 5 and nano A I 2 O increased reactivity and enhanced combustion with Al when compared with commercial I 2 O 5 . [ABSTRACT FROM AUTHOR]

Remarkably effective iodination of reactive aromatics carried out using iodine and iodic acid in 2-methoxyethanol as an efficient and alternative reaction medium. The comparison has been made by carrying out iodination reaction in acetic acid and ethanol. The 2-methoxyethanol is found to be excellent reaction solvent in terms of clean reaction conditions, short reaction time giving quantitative yields of product and no need of further purification.

An efficient, green, rapid multitasking protocol for the selective C-5 substitution of 2-aminothiazole using iodic acid and aqueous PEG-400 was developed. The method found suitable for C-5 substitution i.e. iodination and thiocyanation of 2-amino thiazole using iodine and ammonium thiocyanate respectively. Iodic acid was found to be a good oxidant and aqueous PEG-400 as green reaction solvent. [ABSTRACT FROM AUTHOR]

In this study, the production of particulate films of iodine (V) oxides is investigated. The influence that sonication and solvation of suspended particles in various alcohol/ketone/ester solvents have on the physical structure of spin or drop cast films is examined in detail with electron microscopy, powder x-ray diffraction, and UV-visible absorption spectroscopy. Results indicate that sonicating iodine oxides in alcohol mixtures containing trace amounts of water decreases deposited particle sizes and produces a more uniform film morphology. UV-visible spectra of the pre-cast suspensions reveal that for some solvents, the iodine oxide oxidizes the solvent, producing b and lowering the pH of the suspension. Characterizing the crystals within the cast films reveal their composition to be primarily HI3O8, their orientations to exhibit a preferential orientation, and their growth to be primarily along the ac-plane of the crystal, enhanced at higher spin rates. Spin-coating at lower spin rates produces laminate-like particulate films versus higher density, one-piece films of stacked particles produced by drop casting. The particle morphology in these films consists of a combination of rods, plates, cubes, and rhombohedra structure. [ABSTRACT FROM AUTHOR]

In the first of a series of papers on the iodine(V) oxide system, the chemical and physical properties associated with iodine(V) oxide in its anhydride (I2O5) and hydrated states (HI3O8 and HIO3) are examined. The three forms of the oxide have been investigated utilizing differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and powder X-ray diffraction (PXRD). Furthermore, the hydration rates governing the conversion of the anhydride (I2O5) to the initial hydrate (HI3O8) and later to the final hydrated state (HIO3) are reported and discussed. Results from this study suggest that the hydration mechanism for I2O5→HI3O8 begins with an accelerating period described as a nucleation and growth phase followed by a decelerating period that is diffusion limited. The initial rate of hydration was observed to be governed by a nucleation and growth mechanism, which was inhibited by covering the surface of the particle with an inert metal. Based on this investigation the initial rate of hydration appears to be strongly dependent on the anhydride's available surface area which facilitates nucleation and growth of HI3O8. The final step, HI3O8→HIO3, proceeds through an initial induction period followed by a continuous acceleratory period unlike the first hydration step. [ABSTRACT FROM AUTHOR]

Nucleation of neutral iodine particles has recently been found to involve both iodic acid (HIO 3 ) and iodous acid (HIO 2 ). However, the precise role of HIO 2 in iodine oxoacid nucleation remains unclear. Herein, we probe such a role by investigating the cluster formation mechanisms and kinetics of (HIO 3 ) m (HIO 2 ) n ( m = 0-4, n = 0-4) clusters with quantum chemical calculations and atmospheric cluster dynamics modeling. When compared with HIO 3 , we find that HIO 2 binds more strongly with HIO 3 and also more strongly with HIO 2 . After accounting for ambient vapor concentrations, the fastest nucleation rate is predicted for mixed HIO 3 -HIO 2 clusters rather than for pure HIO 3 or HIO 2 ones. Our calculations reveal that the strong binding results from HIO 2 exhibiting a base behavior (accepting a proton from HIO 3 ) and forming stronger halogen bonds. Moreover, the binding energies of (HIO 3 ) m (HIO 2 ) n clusters show a far more tolerant choice of growth paths when compared with the strict stoichiometry required for sulfuric acid-base nucleation. Our predicted cluster formation rates and dimer concentrations are acceptably consistent with those measured by the Cosmic Leaving Outdoor Droplets (CLOUD) experiment. This study suggests that HIO 2 could facilitate the nucleation of other acids beyond HIO 3 in regions where base vapors such as ammonia or amines are scarce.

A crystalline aluminum iodate acid salt has been synthesized from aluminum particles dissolved in iodic acid solution. The precipitate from solution is aluminum iodate hexahydrate [Al(H 2 O) 6 ](IO 3 ) 3 (HIO 3 ) 2 , as confirmed by X-ray diffraction (XRD) analysis. The method of synthesis first dissolves iodine oxide in water, creating an IO 3 − solution with pH < 0.2. Aluminum nanoparticles are added to the IO 3 − solution and aluminum iodate hexahydrate (AIH) crystals precipitate. The bulk density of the crystalline AIH and Al composite is dependent on the initial water to aluminum concentration ratio during synthesis. Reactivity is characterized in terms of flame speed with measurements purposefully designed to capture less than 1% light emission, resulting in speeds as high as 3200 m/s for AIH + Al composite with a calculated density of 3.43 g/cc. [ABSTRACT FROM AUTHOR]

Transparent conductive graphene films are fabricated by the transfer printing of graphene aqueous dispersion followed by hydrohalic acids and thermal reduction. Results indicate that the graphene film reduced by hydroiodic acid (HI) reduction combined with thermal treatment shows a higher electrical conductivity than that reduced only by thermal treatment at the same transparency. A film with a sheet resistance of ∼ 2400 Ω/sq at a transparency over 72% is obtained at a typical wavelength of 550 nm. [ABSTRACT FROM AUTHOR]

Catalysis of the oxidative processes by iodoarenes has become a promising direction in synthesis. The mechanism, involving the well-known isolable hypervalent iodine species, is generally limited to aromatic iodides, since the corresponding aliphatic species are normally highly unstable. Nevertheless, in this work catalytic amount of several primary, secondary or tertiary iodoalkanes were found to promotes the α-tosyloxylation of a range of ketones with RSO3H, including aliphatic sulfonates. The process, was found to proceed through the oxidative breakdown of the iodoalkane to an inorganic catalytic species (likely IO− or IO2−), thus falling within the previously described catalysis using molecular iodine or inorganic iodides. The catalyst eventually becomes deactivated through the precipitation of an iodine overoxidation product, the structure of which was solved ab initio from the powder diffraction data as a hitherto unreported phase of the iodic acid (HIO3). [ABSTRACT FROM AUTHOR]