H2O Bands Research Articles

JWST Ice Band Profiles Reveal Mixed Ice Compositions in the HH 48 NE Disk

Planet formation is strongly influenced by the composition and distribution of volatiles within protoplanetary disks. With JWST, it is now possible to obtain direct observational constraints on disk ices, as recently demonstrated by the detection of ice absorption features toward the edge-on HH 48 NE disk as part of the Ice Age Early Release Science program. Here, we introduce a new radiative transfer modeling framework designed to retrieve the composition and mixing status of disk ices using their band profiles, and apply it to interpret the H2O, CO2, and CO ice bands observed toward the HH 48 NE disk. We show that the ices are largely present as mixtures, with strong evidence for CO trapping in both H2O and CO2 ice. The HH 48 NE disk ice composition (pure versus polar versus apolar fractions) is markedly different from earlier protostellar stages, implying thermal and/or chemical reprocessing during the formation or evolution of the disk. We infer low ice-phase C/O ratios around 0.1 throughout the disk, and also demonstrate that the mixing and entrapment of disk ices can dramatically affect the radial dependence of the C/O ratio. It is therefore imperative that realistic disk ice compositions are considered when comparing planetary compositions with potential formation scenarios, which will fortunately be possible for an increasing number of disks with JWST.

CO2‐Dependence of Longwave Clear‐Sky Feedback Is Sensitive to Temperature

AbstractCO2 absorbs and emits radiation, which allows it to act both as radiative forcing and feedback. Recent work has shown CO2’s feedback effect becomes dominant in hothouse climates, giving rise to a non‐monotonic climate sensitivity around 310 K. However, CO2’s feedback effect in colder climates is less clear. We use a line‐by‐line model to explore the CO2‐dependence of the longwave clear‐sky feedback and identify a dividing temperature. Above 290 K, feedback increases with CO2 concentration; below 290 K, feedback decreases with CO2 concentration. We explain this dependence in terms of spectral competition under CO2 increases. In hot climates, CO2’s moderate feedback replaces near‐zero feedback from the H2O bands; in cold climates, CO2’s moderate feedback replaces the large feedback from the surface. Given that global mean temperature is currently close to 290 K, our results suggest that feedback CO2‐dependence is weak at present but can be important in past and future climates.

GOALS-JWST: Mid-infrared Molecular Gas Excitation Probes the Local Conditions of Nuclear Star Clusters and the Active Galactic Nucleus in the LIRG VV 114

The enormous increase in mid-IR sensitivity and spatial and spectral resolution provided by the JWST spectrographs enables, for the first time, detailed extragalactic studies of molecular vibrational bands. This opens an entirely new window for the study of the molecular interstellar medium in luminous infrared galaxies (LIRGs). We present a detailed analysis of rovibrational bands of gas-phase CO, H2O, C2H2, and HCN toward the heavily obscured eastern nucleus of the LIRG VV 114, as observed by NIRSpec and the medium resolution spectrograph on the Mid-InfraRed Instrument (MIRI MRS). Spectra extracted from apertures of 130 pc in radius show a clear dichotomy between the obscured active galactic nucleus (AGN) and two intense starburst regions. We detect the 2.3 μm CO bandheads, characteristic of cool stellar atmospheres, in the star-forming regions, but not toward the AGN. Surprisingly, at 4.7 μm, we find highly excited CO (T ex ≈ 700–800 K out to at least rotational level J = 27) toward the star-forming regions, but only cooler gas (T ex ≈ 200 K) toward the AGN. We conclude that only mid-infrared pumping through the rovibrational lines can account for the equilibrium conditions found for CO and H2O in the deeply embedded starbursts. Here, the CO bands probe regions with an intense local radiation field inside dusty young massive star clusters or near the most massive young stars. The lack of high-excitation molecular gas toward the AGN is attributed to geometric dilution of the intense radiation from the bright point source. An overview of the relevant excitation and radiative transfer physics is provided in an appendix.

Machine learning model for deep exploration: Utilizing short wavelength infrared (SWIR) of hydrothermal alteration minerals in the Qianchen gold deposit, Jiaodong Peninsula, Eastern China

The Jiaodong Peninsula in the eastern North China Craton is renowned globally as a major gold province. Notably, the Jiaojia orefield is an important gold-producing district in this region, and its depths are inferred to offer substantial prospecting potential, underscoring the need for innovative exploration tools to uncover concealed orebodies. The Qianchen gold deposit in the southern part of the Jiaojia orefield is characterized by the disseminated-stockwork-style orebodies at depths of ca. –1000 to –1800 m, with three mineralization stages, namely (I) pre-ore K-feldspar-quartz stage, (II) quartz-sericite-gold-polymetallic sulfide stage (main Au mineralization stage), and (III) post-ore quartz-calcite stage. Systematic short-wavelength infrared (SWIR) spectral analysis reveals that sericite group minerals developing in Stage II are the predominant and wide-distributed alteration minerals at Qianchen. Their spectral characteristics demonstrate a shift in the Al-OH absorption feature wavelength positions (Pos2200) to longer wavelengths (>2205 nm) within the orebodies. This shift is likely due to strong water–rock interactions leading to Fe and Mg substituting for Al in octahedral sites. Orthogonal partial least squares discriminant analysis (OPLS-DA) indicates that the H2O, OH, and FeOH spectral bands (Variable Importance in the Projection (VIP) ≥ 1) of sericite are crucial for distinguishing between gold ores and barren wall rocks. Additionally, Long Short-Term Memory (LSTM) models demonstrate that spectral data of sericite can be used to predict ore samples with an accuracy of 82 %, validated by receiver operating characteristic analysis (84 %), and blind test results demonstrate that the predicted grade closely aligns with the actual grade. Therefore, it is concluded that SWIR spectral characteristics of sericite group minerals can serve as an effective indicator for prospecting the Qianchen concealed gold mineralization. This study highlights the potential of coupling between machine learning and SWIR spectral data of alteration minerals to uncover the concealed lode gold mineralization.

Infrared Characterization of the Products of the Reaction between the Criegee Intermediate CH3CHOO and HCl.

The rapid reactions between Criegee intermediates and hydrogen halides play important roles in atmospheric chemistry, particularly in the polluted urban atmosphere. Employing a step-scan Fourier transform spectrometer, we recorded infrared absorption spectra of transient species and end products of the reaction CH3CHOO + HCl in a flowing mixture of CH3CHI2/HCl/O2/N2 irradiated at 308 nm. Bands at 1453.6, 1383.7, 1357.9, 1323.8, 1271.8, 1146.2, 1098.2, 1017.5, 931.5, and 847.0 cm-1 were observed and assigned to the anti-conformer of chloroethyl hydroperoxide (anti-CEHP or anti-CH3CHClOOH). In addition, absorption bands of H2O and acetyl chloride [CH3C(O)Cl, at 1819.1 cm-1] were observed; some of them were produced from the secondary reactions of CH3CHClO + O2 → CH3C(O)Cl + HO2 and OH + HCl → H2O + Cl, according to temporal profiles of H2O and CH3C(O)Cl. These secondary reactions are conceivable because the nascent formation of CH3CHClO + OH via decomposition of internally excited CEHP was predicted by theory, and both HCl and O2 are major species in the system. The nascent formation of CH3CHClO + OH appears to be more important than that of CH3C(O)Cl + H2O, consistent with theoretical predictions. By adding methanol to deplete some anti-CH3CHOO, we observed only anti-CEHP with a reduced proportion; this observation indicates that the conversion from syn-CEHP, expected to be produced from syn-CH3CHOO + HCl, to anti-CEHP is facile. We also estimated the overall rate coefficient of the reaction syn-/anti-CH3CHOO + HCl to be kHCl = (2.7 ± 1.0) × 10-10 cm3 molecule-1 s-1 at ∼70 Torr and 298 K; this rate coefficient is about six times the only literature value kHClsyn = (4.77 ± 0.95) × 10-11 cm3 molecule-1 s-1 reported for syn-CH3CHOO + HCl by Liu et al., indicating that anti-CH3CHOO reacts with HCl much more rapidly than syn-CH3CHOO.

The First JWST Spectral Energy Distribution of a Y Dwarf

We present the first JWST spectral energy distribution of a Y dwarf. This spectral energy distribution of the Y0 dwarf WISE J035934.06−540154.6 consists of low-resolution (λ/Δλ ∼100) spectroscopy from 1–12 μm and three photometric points at 15, 18, and 21 μm. The spectrum exhibits numerous fundamental, overtone, and combination rotational–vibrational bands of H2O, CH4, CO, CO2, and NH3, including the previously unidentified ν 3 band of NH3 at 3 μm. Using a Rayleigh–Jeans tail to account for the flux emerging at wavelengths greater than 21 μm, we measure a bolometric luminosity of 1.523 ± 0.090 × 1020 W. We determine a semiempirical effective temperature estimate of K using the bolometric luminosity and evolutionary models to estimate a radius. Finally, we compare the spectrum and photometry to a grid of atmospheric models and find reasonably good agreement with a model having T eff = 450 K, log g = 3.25 [cm s−2], and [M/H] = −0.3. However, the low surface gravity implies an extremely low mass of 1 M Jup and a very young age of 20 Myr, the latter of which is inconsistent with simulations of volume-limited samples of cool brown dwarfs.

The H2O–CO2 continuum around 3.1, 5.2 and 8.0 [formula omitted]m: New measurements and validation of a previously proposed [formula omitted] factor

The H2O–CO2 continuum has been measured, at room temperature, at discrete spectral points in the 1100–1500, 1800–2000, and 3100–3300 cm−1 intervals. Our results are in good agreement with previous experimental values in the low frequency wing of the ν2 band of H2O when the associated uncertainties are taken into account. Furthermore, they confirm the quality, in this region, of a χ factor previously adjusted on measurements in the 100–1500 cm−1 range, and prove its validity in the blue side of the ν2 band as well as in the region around 3.1 μm, which have been experimentally studied for the first time in this work. Together with recent measurements in the 1.6 μm, 2.3 μm and far infrared regions, our results contribute to the progressive building-up of a data set for the modeling of the absorption by CO2+H2O mixtures throughout the infrared, which is needed for studies of CO2-rich planetary atmospheres.

Infrared H2O Absorption in Massive Protostars at High Spectral Resolution: Full Spectral Survey Results of AFGL 2591 and AFGL 2136

We have performed a high-resolution 4–13 μm spectral survey of the hot molecular gas associated with the massive protostars AFGL 2591 and AFGL 2136. Here we present the results of the analysis of the ν 2 band of H2O, detected with the Echelon Cross Echelle Spectrograph on board the Stratospheric Observatory for Infrared Astronomy between wavelengths of 5 and 8 μm. All lines are seen in absorption. Rotation diagrams indicate that the gas is optically thick and lines are observed to saturate at 40% and 15% relative to the continuum for AFGL 2136 and AFGL 2591, respectively. We applied two curve of growth analyses to derive the physical conditions, one assuming a foreground origin and one a circumstellar disk origin. We find temperatures of 400–600 K. A foreground origin would require the presence of externally heated clumps that are smaller than the continuum source. The disk analysis is based on stellar atmosphere theory, which takes into consideration the temperature gradient in the disk. We discuss the challenges with each model, taking into consideration the properties of other species detected in the spectral survey, and conclude that further modeling efforts are required to establish whether the absorption has a disk or foreground origin. The main challenge to the foreground model is that molecules are expected to be observed in emission. The main challenges to the disk model are the midplane heating mechanism and the presence of narrow absorption lines shifted from the systemic velocity.

Top-of-the-atmosphere and Vertical Cloud Structure of a Fast-rotating Late T Dwarf

Only a handful of late T brown dwarfs have been monitored for spectrophotometric variability, leaving incomplete the study of the atmospheric cloud structures of the coldest brown dwarfs, which share temperatures with some cold, directly imaged exoplanets. 2MASS J00501994–332240 is a T7.0 rapidly rotating, field brown dwarf that showed low-level photometric variability in data obtained with the Spitzer Space Telescope. We monitored 2MASS J00501994–332240 during ∼2.6 hr with MOSFIRE, installed at the Keck I telescope, with the aim of constraining its near-infrared spectrophotometric variability. We measured fluctuations with a peak-to-peak amplitude of 1.48% ± 0.75% in the J-band photometric light curve, an amplitude of 0.62% ± 0.18% in the J-band spectrophotometric light curve, an amplitude of 1.26% ± 0.93% in the H-band light curve, and an amplitude of 5.33% ± 2.02% in the CH4 − H2O band light curve. Nevertheless, the Bayesian information criterion does not detect significant variability in any of the light curves. Thus, given the detection limitations due to the MOSFIRE sensitivity, we can only claim tentative low-level variability for 2M0050–3322 in the best-case scenario. The amplitudes of the peak-to-peak fluctuations measured for 2MASS J00501994–332240 agree with the variability amplitude predictions of general circulation models for a T7.0 brown dwarf for an edge-on object. Radiative transfer models predict that the Na2S and KCl clouds condense at pressures lower than that traced by the CH4–H2O band, which might explain the higher peak-to-peak fluctuations measured for this light curve. Finally, we provide a visual recreation of the map provided by general circulation models and the vertical structure of 2MASS J00501994–332240 provided by radiative transfer models.

Remarkably High Conductivity and Power Factor in D–D′‐type Thermoelectric Polymers Based on Indacenodithiophene

AbstractThree p‐type thermoelectric (TE) polymers based on the indacenodithiophene moiety substituted with bis(alkylsulfanyl)methylene side‐chains (IDTS) are synthesized. The TE characteristics of IDTS‐based donor–donor’ (D–D′) type PIDTSDTTT and donor–acceptor (D–A) type polymers, PIDTSBT and PIDTS2FBT are investigated. Remarkably higher electrical conductivity (σ = ≈1000 S cm−1) and power factor (PF = ≈120 μW m−1 K−2) by doping with AuCl3 are measured for PIDTSDTTT compared to D–A type polymers. The higher σ of PIDTSDTTT originates from its higher carrier concentration compared to those of PIDTSBT and PIDTS2FBT. Moreover, the facile polaron‐to‐bipolaron transition is measured, and the charge carriers are calculated to be more stable with extended delocalization in PIDTSDTTT compared to D–A polymers. The significantly higher doping stability in PIDTSDTTT can be explained in terms of the higher conduction band of bipolarons than the valence band of O2 and H2O, which blocks the facile reduction of bipolarons in air. The energetic structures of doped polaron and bipolaron states, as well as pristine TE polymers, must be carefully considered to realize efficient and stable p‐type thermoelectric polymers, where a D–D′ type structure with further enhanced carrier mobility can be considered as a potential molecular framework.

The annual cycle of water vapor above gale crater as retrieved by CRISM and compared to ChemCam passive sky spectroscopy

Using spectra returned from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) aboard the Mars Reconnaissance Orbiter (MRO), we report atmospheric water vapor column abundances at a spatial resolution of ~ 1 km from observations taken over Gale crater, the landing site of the Mars Science Laboratory (MSL). The observations span a little more than 3 Mars years (MY) from MY 28 at Ls = 116° (October 04, 2006) to MY 31 at Ls = 101° (April 24, 2012). The retrievals were performed using an improved algorithm to correct for the changes in wavelength in the cross-track direction of CRISM images, also known as the “spectral smile”, allowing for a larger fraction of area from each observation to be covered. The water vapor column abundances are retrieved using the strong absorption band of H2O centered at 2600 nm. The seasonal cycle of water vapor above Gale is compared against that from reprocessed and new MSL Curiosity rover ChemCam passive sky observations using updated gas absorption parameters and covering the period between MY 31 at Ls = 291° (March 30, 2013) and MY 35 at Ls = 42° (June 20, 2019). The retrieved annual variation of water vapor from CRISM and ChemCam both display a similar trend with respect to the timing of the maximum and minimum in water abundance, with only minor differences caused by the interannual differences in water vapor and the different retrieval approaches between both instruments, addressing a previously existing discrepancy between ChemCam and CRISM water vapor column abundances.

The adsorption capacity of root exudate organic carbon onto clay mineral surface changes depending on clay mineral types and organic carbon composition

Organic compounds released by plant roots may be protected from microbial decomposition through mineral-organic association. Yet, the adsorption characteristics of root exudates organic compounds by 2:1 clay minerals and the underlying mechanisms remain not fully understood. This study considers glucose and oxalic acid separately and added into quartz, illite, vermiculite, and montmorillonite in solution at different concentrations and shaking for 4 h before performing total organic carbon (TOC), Fourier Transformation Infrared (FTIR) spectroscopy, conventional X-Ray Diffraction (XRD) analysis and Brunauer-Emmett-Teller measurement with N2 gas adsorption. According to the results, the Langmuir-Freundlich isotherm curves showed that quartz and the 2:1 clay minerals can adsorb oxalic acid more than glucose and the adsorption capacity fell in the order of quartz < illite < vermiculite < montmorillonite for each compound. The glucose and oxalic acid adsorption increased with the decrease of main mineral reflection (d001), external specific surface area (ESSA), and the reduction of specific mineral functional groups, such as OH–Mg2–Al, Al–OH, Si–O, and Si–O–Si. In addition, the FWHM increased for montmorillonite and vermiculite following the addition of glucose and oxalic acid. These results indicated that the adsorption of either glucose or oxalic acid caused a modification of the crystalline structures of the clay minerals. The high signal of the H2O band for glucose addition and new bands of oxalic acid (COO−; CO−, COOH−) for oxalic acid addition were observed, indicating that glucose and oxalic acid were entrapped into micropores of the minerals, including quartz through hydrogen bonding and oxalic acid functional groups, respectively. Our study suggested that the adsorption of glucose and oxalic acid were controlled by the clay mineral properties (types, external surface areas, and modified crystalline structure), and organic carbon types. This study reveals the characteristics of the adsorption of root exudate organic compounds by clay minerals surface and highlights the role of 2:1 clay minerals in the stabilization of root exudate organic compounds.

CdS nanodots adorned (020)-featured WO3·H2O nanoplates heterojunction with augmented photocatalytic hydrogen production under Z-scheme charge transfer mechanism

In this paper, controllable nucleation and growth of CdS nanodots on the (020)-featured WO3·H2O nanoplates has been successfully accomplished to prepare CdS-WO3·H2O heterojunction with high-quality interfacial contact through a slow release of Cd2+ and S2- from the gradual self-loop hydrolysis of cadmium acetate and thioacetamide. The chemical and structural characteristics of as-prepared samples before and after heat treatment are detailedly investigated by TG-DSC, XRD, Raman, XPS, FESEM and HRTEM, as well as their light absorption performance from UV-Vis DRS. The maximum average hydrogen production rate for CdS-WO3·H2O reaches 2.15 mmol·g−1·h−1 under 300 W Xe lamp irradiation (λ > 420 nm) using lactic acid as sacrificial reagent, which is 8.27 and 2.72 times as much as CdS and CdS-WO3, respectively. According to band alignment, CdS-WO3·H2O exhibits greater energy difference of Fermi level than CdS-WO3, and augmented photocatalytic performance should arise from efficient Z-scheme charge transfer mechanism under stronger built-in electric field, in which the conduction band electrons of WO3·H2O and valence band holes of CdS are expected to effectively recombine at their interfacial zones, while the conduction band electrons of CdS and valence band holes of WO3·H2O contribute to the reduction of H+ and oxidation of lactic acid.

Measurements and calculations of Xe-broadening and shift parameters of water vapour transitions in a wide spectral region

The water vapour line broadening (γ) and shifting (δ) coefficients for 687 lines of 14 vibrational bands ν1, ν3, 2ν2, ν1 + ν2, ν2 + ν3, 3ν2, 2ν2 + ν3, ν1 + 2ν2, ν1 + ν3, 2ν1, 2ν3, 4ν2, 6ν2, and 3ν2 + ν3 induced by xenon pressure were measured with Bruker IFS 125 FTIR spectrometer. The measurements were performed at room temperature, at the spectral resolution of 0.01 cm−1 and in a wide pressure range of Xe. The broadening and shift coefficients were calculated using a semi-classical method. The intermolecular potential was taken as the sum of the anisotropic atom–atom potential and vibrationally and rotationally dependent isotropic Lennard-Jones potential. The optimal sets of potential parameters that gave the best agreements with measured coefficients γ and δ for each vibrational band were found. The measured coefficients γ were combined with the data found earlier for the ν1 + ν2 + ν3 bands as well as with those reported in literature for the ν2, ν1, ν3, 2ν1 + 2ν3, 2ν1 + 2ν2 + ν3 and 3ν1 + ν3 bands and N = 820 coefficients γ of19 vibrational bands of H2O perturbed by Xe were fitted to the empirical functions. The computed coefficients γ and δ derived from the semi-classical method as well as from the fitted parameters were compared statistically to measurements.

Water Molecules in Channels of Natural Emeralds from Dayakou (China) and Colombia: Spectroscopic, Chemical and Crystal Structural Investigations

H2O molecules in emerald channels have been extensively discussed over the past half century. Recent studies paid attention to their classification and coordination, but have mostly focused on the type related to Na+. There are few works on the other types, and the related infrared (IR) absorption bands are rather controversial. This paper investigated natural emeralds from China and Colombia by means of micro-Fourier transform infrared (μ-FTIR) spectroscopy, micro-confocal Raman spectroscopy, and laser ablation-inductively coupled plasma mass spectrometry (LA-ICP-MS). The results suggested that doubly (IId) and singly (IIs) coordinated H2O molecules were incorporated in natural emerald channels. Type IId H2O predominated in those emeralds with relatively low alkali content. As the alkali content increased, the proportion of type IIs H2O rose, stemming from the decrease of the H2OII/Na+ apfu ratio. Moreover, IR bands of H2O corresponding to Li+ and Cs+ were tentatively ascribed here. IR bands for D2O and HDO in Colombian sample were observed in the range of 2600–2850 cm−1 and preliminarily assigned, which might be a potential tool for emerald origin determination. Our work expanded the existing classification of water molecules in emerald channels and redefined the controversial IR absorption bands.

Near-IR study of the impact of alkyl-ammonium and -phosphonium cations on the hydration of montmorillonite

Organo-montmorillonites (O-Mts) are attractive inorganic-organic hybrid materials used in numerous industrial applications. In this work the adsorption of water onto montmorillonite saturated with the alkylammonium and alkylphosphonium cations tetramethyl-(Me4-N/P), tetrabutyl-(Bu4-N/P) and tetraoctyl-(Oc4-N/P) was studied. The effect of the organic cation size and particularly of the central atom of the organic cation head-group (N vs P) was followed at different relative humidities (RH). The samples were characterized using carbon analysis, N2 adsorption, X-ray powder diffraction analysis (XRPD), and infrared spectroscopy (IR) in the middle-IR (MIR) and near-IR (NIR) regions. Gravimetric analysis and NIR spectroscopy were used to monitor the hydration of the O-Mts. A gradual shift of the combination band of water molecules, (ν+δ)H2O, to lower wavenumbers on increasing the amount of adsorbed water indicated an increase in the number of H2O molecules involved in stronger hydrogen bonds. A shift of the 2νCH3 band to higher wavenumber with increasing RH, observed for Me4-N/P-Mts and Bu4-N-Mt, provided evidence that water molecules interacted directly with the methyl groups of the Me4-N/P and Bu4-N cations. Gravimetric analysis confirmed that at each RH the content of adsorbed water decreased in the direction Me4-N/P-Mts ⟹ Bu4-N/P-Mts ⟹ Oc4-N/P-Mts due to the increasing hydrophobicity of the organic cations. The area of the (ν+δ)H2O band, reflecting the degree of O-Mt hydration, confirmed the results obtained by gravimetry, i.e. the content of adsorbed water decreased as the size of the organic cation increased. The results of the NIR spectroscopy as well as gravimetric analysis showed a higher hydrophobicity of O-Mts saturated with alkylphosphonium cations compared to their alkylammonium counterparts. The obtained results showed that NIR spectroscopy is a very useful method for the characterization of organo-montmorillonite hydration.

Interactive mechanism of plasma-assisted CO2 capture for calcium looping cycle via in-situ DRIFTS

Plasma-assisted calcium looping (CaL) process has been proposed for improvement of CO2 capture technique. The conventional CaL process has a critical drawback such as low energy efficiency associated with a high temperature required for both the capture and release of CO2. In the present study, the plasma-assisted CO2 capture was proposed to improve the reactivity of CaO carbonation. An in-situ DRIFTS reactor was designed to investigate the carbonation reactivity in the presence of plasma on the CaO. The mixture of CO2 and He was injected into the reactor and the plasma was generated on the CaO surface at the fixed input power of 20 W. The IR spectra were obtained according to the temperature ranging from 100 to 500℃. In general, the reaction of CO2 with CaO is thermodynamically more favorable than that with Ca(OH)2. When the plasma was applied, however, the reaction pathway was changed to enhance the reaction of CO2 with Ca(OH)2. The evidence on the change of reaction pathway was validated by detecting the H2O band at the temperate higher than 200℃ under the plasma, even though the H2O band was removed after the calcination at 900℃. Consequently, the CO2 intensity was notably decreased by 33.33 % at 500 °C, which implied that the reactivity of CaO carbonation was improved. Based on the in-situ DRIFTS analysis, a lab-scale plasma reactor was designed for the CaO carbonation with the plasma-excited CO2. The effect of CO2 concentration on the CO2 conversion and energy efficiency was presented in the plasma-assisted CaL process.

Measurements and calculations of xenon broadening and shift parameters of water vapour transitions for ν1 + ν2 + ν3 band

The water vapour line broadening and shifting of 72 lines in the ν1 + ν2 + ν3 vibrational band of H2O (in the 8603–8997 cm−1 spectral region) induced by xenon pressure were measured with a Bruker IFS HR FTIR spectrometer. These measurements were performed at room temperature, at a spectral resolution of 0.01 cm−1 and over a wide range of Xe pressure. The broadening and shift coefficients were also calculated using a semi-classical method. The intermolecular potential was taken as the sum of the anisotropic atom–atom potential and the effective vibrationally and rotationally dependent isotropic Lennard–Jones potential.The measured coefficients γ and δ were combined with data from the literature on the ν2, ν1, ν3, 2ν1 + 2ν3, 2ν1 + 2ν2 + ν3, and 3ν1 + ν3 bands, and optimal sets of potential parameters were found that gave the best agreement with the measured broadening coefficients. A strong influence of the imaginary part of the scattering matrix on the calculated values of the γ and δ coefficients was observed. The results were compared with those for He-, Ar-, and Kr-broadenings. The measured broadening coefficients were fitted to empirical expressions. The calculated values of the γ and δ coefficients were compared statistically to the measured values.

Catalytic system based on recyclable Fe0 and ZnS semiconductor for UV-promoted degradation of chlorinated organic compounds

Fe0 (ZVI) is one of the most effective reactants for treatment of water contaminated with chlorinated hydrocarbons, pollutants recalcitrant to degradation. Unfortunately, ZVI use is limited by corrosion and loss of reactivity over time. In order to suppress oxidation and passivation phenomena of iron, in this study ZVI was coupled to a suitable semiconductor (ZnS). Under UV light, electrons in the valence band of ZnS are promoted in the conducting band (ECB = − 1.04 eV vs NHE) and are able to reduce Fe2+ to Fe0 (E0 = − 0.44 eV vs NHE). The ZnS_ZVI composite was simply prepared by coating commercial ZnS with Fe0 obtained by reducing Fe (II) salt with sodium borohydride. The achieved ZnS_ZVI catalytic system was characterized by FESEM, WAXD, Raman and N2 adsorption at −196 °C, with the aim to analyze morphology and crystalline structure of both components of the ZnS_ZVI system. Catalytic activity tests showed that ZnS_ZVI is effective in degrading probe molecules, eriochrome black T dye (EBT) and chlorobenzene (PhCl), from aqueous solutions under UV light irradiation. The experimental results show that in both cases the reductive action of Fe0 on the N = N bond of EBT and C-Cl of PhCl is synergistically coupled to the oxidative action of ZnS towards by-products. OH radicals, generated by the reaction between the electron holes in the valence band of ZnS and H2O (OH−), were indeed confirmed by photoluminescence analysis. Recyclability tests indicate that ZnS_ZVI is highly stable since its catalytic activity, on both probe molecules, remains unchanged even after several cycles of reuse under UV irradiation. ZnS_ZVI catalytic behavior towards EBT has been carefully analyzed and a possible mechanism of EBT degradation has been proposed, which involves the formation of a Fe2+-EBT complex whose structure has also been suggested.

High-Pressure Optical Measurements of Temperature at Turbine Rotor Inlet Conditions

Abstract In gas turbine engines, the measurement of the rotor inlet temperature remains particularly challenging because of harsh operating conditions and limited access. The integrated spectral band ratio (ISBR) method is a nonintrusive optical emission gas temperature measurement technique suitable for this application. Optical fibers made of sapphire were used to transmit the radiative signal from the postcombustion zone to a Fourier transform infrared (FTIR) spectrometer. The ratio of spectral bands of H2O, nominally 100 cm−1 wide between 4600 and 6200 cm−1, was used to infer temperature. ISBR and thermocouple measurements were obtained during two temperature sweeps: one at high load and one at low load (pressures of 1.2 and 0.7 MPa, respectively). The average of three thermocouples 76 mm downstream of the ISBR measurements was on the order of 200 K lower than the ISBR temperatures, consistent with a radiative correction and the heat loss between the two measurements. The change in ISBR temperature (95 K) during the sweep was similar to the change in average thermocouple temperature (89 K). Repeatability of the optical measurement at a given operating condition was on the order of ±15 K and the absolute uncertainty of a single ISBR temperature measurement was estimated to be ±61 K. A linear correlation with an R2 value of 0.97 was also found between raw optical signal and thermocouple measurements, suggesting that once a calibrated measurement is obtained.