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Understanding the structures and reaction mechanisms of interfacial active sites in the Fisher-Tropsch synthesis reaction is highly desirable but challenging. Herein, we show that the ZrO 2 -Ru interface could be engineered by loading the ZrO 2 promoter onto silica-supported Ru nanoparticles (ZrRu/SiO 2 ), achieving 7.6 times higher intrinsic activity and ~45% reduction in the apparent activation energy compared with the unpromoted Ru/SiO 2 catalyst. Various characterizations and theoretical calculations reveal that the highly dispersed ZrO 2 promoter strongly binds the Ru nanoparticles to form the Zr-O-Ru interfacial structure, which strengthens the hydrogen spillover effect and serves as a reservoir for active H species by forming Zr-OH* species. In particular, the formation of the Zr-O-Ru interface and presence of the hydroxyl species alter the H-assisted CO dissociation route from the formyl (HCO*) pathway to the hydroxy-methylidyne (COH*) pathway, significantly lowering the energy barrier of rate-limiting CO dissociation step and greatly increasing the reactivity. This investigation deepens our understanding of the metal-promoter interaction, and provides an effective strategy to design efficient industrial Fisher-Tropsch synthesis catalysts. Understanding the structures of interfacial active sites is crucial in heterogeneous catalysis. Here the authors demonstrate that a ZrO 2 -Ru interface site significantly enhances reactivity in the Fischer-Tropsch to olefins process by altering the H-assisted CO dissociation route due to the presence of hydroxy species associated with Zr-OH*.

Large haloes of diffuse molecular gas discovered around high-redshift starburst galaxies show that galactic feedback, coupled to turbulence and gravity, extends the starburst phase instead of quenching it. Far-away gas feeds star formation Starburst galaxies in the early Universe form stars so rapidly that the gas reservoirs that feed star formation should quickly be depleted. However, star formation goes on for longer than can be explained by the amount of gas inside the galaxies. CH + is a useful tracer of the physical conditions of these galaxies because it can form in cold gas only in the presence of strong ultraviolet radiation or mechanical shocks. Edith Falgarone et al . report spectra in which they see CH + in both emission and absorption in a sample of starburst galaxies at redshifts of around 2.5. In emission, the CH + lines are very wide and result from shocks. In absorption, the lines reveal the presence of very turbulent gas extending far outside the star-forming cores of the galaxies. These findings suggest that the feedback process that regulates star formation involves reservoirs of gas far outside the galaxies. Starburst galaxies at the peak of cosmic star formation 1 are among the most extreme star-forming engines in the Universe, producing stars over about 100 million years (ref. 2 ). The star-formation rates of these galaxies, which exceed 100 solar masses per year, require large reservoirs of cold molecular gas 3 to be delivered to their cores, despite strong feedback from stars or active galactic nuclei 4 , 5 . Consequently, starburst galaxies are ideal for studying the interplay between this feedback and the growth of a galaxy 6 . The methylidyne cation, CH + , is a most useful molecule for such studies because it cannot form in cold gas without suprathermal energy input, so its presence indicates dissipation of mechanical energy 7 , 8 , 9 or strong ultraviolet irradiation 10 , 11 . Here we report the detection of CH + ( J  = 1–0) emission and absorption lines in the spectra of six lensed starburst galaxies 12 , 13 , 14 , 15 at redshifts near 2.5. This line has such a high critical density for excitation that it is emitted only in very dense gas, and is absorbed in low-density gas 10 . We find that the CH + emission lines, which are broader than 1,000 kilometres per second, originate in dense shock waves powered by hot galactic winds. The CH + absorption lines reveal highly turbulent reservoirs of cool (about 100 kelvin), low-density gas, extending far (more than 10 kiloparsecs) outside the starburst galaxies (which have radii of less than 1 kiloparsec). We show that the galactic winds sustain turbulence in the 10-kiloparsec-scale environments of the galaxies, processing these environments into multiphase, gravitationally bound reservoirs. However, the mass outflow rates are found to be insufficient to balance the star-formation rates. Another mass input is therefore required for these reservoirs, which could be provided by ongoing mergers 16 or cold-stream accretion 17 , 18 . Our results suggest that galactic feedback, coupled jointly to turbulence and gravity, extends the starburst phase of a galaxy instead of quenching it.

Facile C-C bond formation is essential to the formation of long hydrocarbon chains in Fischer-Tropsch synthesis. Various chain growth mechanisms have been proposed previously, but spectroscopic identification of surface intermediates involved in C-C bond formation is scarce. We here show that the high CO coverage typical of Fischer-Tropsch synthesis affects the reaction pathways of C 2 H x adsorbates on a Co(0001) model catalyst and promote C-C bond formation. In-situ high resolution x-ray photoelectron spectroscopy shows that a high CO coverage promotes transformation of C 2 H x adsorbates into the ethylidyne form, which subsequently dimerizes to 2-butyne. The observed reaction sequence provides a mechanistic explanation for CO-induced ethylene dimerization on supported cobalt catalysts. For Fischer-Tropsch synthesis we propose that C-C bond formation on the close-packed terraces of a cobalt nanoparticle occurs via methylidyne (CH) insertion into long chain alkylidyne intermediates, the latter being stabilized by the high surface coverage under reaction conditions. The mechanism by which C-C bonds form during Fischer-Tropsch synthesis remains debated while spectroscopic identification of reaction intermediates remains scarce. Here, the authors identify alkylidynes as reactive intermediates for C-C bond formation on cobalt terrace sites and moreover show that these intermediates are stabilized by the high surface coverage typical for Fischer-Tropsch synthesis.

Laser-induced fluorescence is a widely used technique for measuring the concentrations of gaseous species in reactive environments. To determine absolute number densities from laser-induced fluorescence signals, the collisional quenching rate of the excited state molecule needs to be known. The methylidyne (CH) radical is an important species in combustion, catalysis, and plasma applications, the latter two of which require laser-induced fluorescence measurements at lower temperatures. Quantitative detection of CH is also needed for photofragmentation laser-induced fluorescence measurements, where CH is produced by photolysis of a larger molecule, such as the methyl radical (CH3), by a pump laser, and then is excited by a probe laser to induce fluorescence. We have measured the collisional quenching rates of CH(A) by methanol, methane, oxygen, nitrogen, and acetone at temperatures between 300 and 600 K. The CH(A) quenching rate by methanol, which is highly relevant in catalysis, has not previously been studied. The quenching rates for acetone, which is used as a precursor to photolytically produce methyl, and methane have been studied but not at elevated temperatures. We find that methanol and acetone both have high quenching rate coefficients of 2.2·10-10 to 2.5·10-10 cm3/s with only a small temperature dependence. We also find that the quenching rate of methane has a significant temperature dependence ranging from 2.5·10-11 cm3/s at 300 K to 5.0·10-11 cm3/s at 600 K. The quenching rates determined in this work are important for laser-induced fluorescence studies of catalysis, plasmas, and combustion processes.

Since the postulation of carbenes by Buchner (1903) and Staudinger (1912) as electron-deficient transient species carrying a divalent carbon atom, carbenes have emerged as key reactive intermediates in organic synthesis and in molecular mass growth processes leading eventually to carbonaceous nanostructures in the interstellar medium and in combustion systems. Contemplating the short lifetimes of these transient molecules and their tendency for dimerization, free carbenes represent one of the foremost obscured classes of organic reactive intermediates. Here,we afford an exceptional glance into the fundamentally unknown gas-phase chemistry of preparing two prototype carbenes with distinct multiplicities—triplet pentadiynylidene (HCCCCCH) and singlet ethynylcyclopropenylidene (c-C₅H₂) carbene—via the elementary reaction of the simplest organic radical—methylidyne (CH)—with diacetylene (HCCCCH) under single-collision conditions. Our combination of crossed molecular beam data with electronic structure calculations and quasi-classical trajectory simulations reveals fundamental reaction mechanisms and facilitates an intimate understanding of bond-breaking processes and isomerization processes of highly reactive hydrocarbon intermediates. The agreement between experimental chemical dynamics studies under single-collision conditions and the outcome of trajectory simulations discloses that molecular beam studies merged with dynamics simulations have advanced to such a level that polyatomic reactions with relevance to extreme astrochemical and combustion chemistry conditions can be elucidated at the molecular level and expanded to higher-order homolog carbenes such as butadiynylcyclopropenylidene and triplet heptatriynylidene, thus offering a versatile strategy to explore the exotic chemistry of novel higherorder carbenes in the gas phase.

Complex organosulfurmolecules are ubiquitous in interstellarmolecular clouds, but their fundamental formation mechanisms have remained largely elusive. These processes are of critical importance in initiating a series of elementary chemical reactions, leading eventually to organosulfur molecules—among them potential precursors to iron-sulfide grains and to astrobiologically important molecules, such as the amino acid cysteine. Here, we reveal through laboratory experiments, electronic-structure theory, quasi-classical trajectory studies, and astrochemical modeling that the organosulfur chemistry can be initiated in star-forming regions via the elementary gas-phase reaction of methylidyne radicals with hydrogen sulfide, leading to thioformaldehyde (H₂CS) and its thiohydroxycarbene isomer (HCSH). The facile route to two of the simplest organosulfur molecules via a single-collision event affords persuasive evidence for a likely source of organosulfur molecules in star-forming regions. These fundamental reaction mechanisms are valuable to facilitate an understanding of the origin and evolution of the molecular universe and, in particular, of sulfur in our Galaxy.

In this study a high‐performance hybrid X‐ray detector incorporating CdSe nanoplatelets (NPLs) is presented into a PBDB‐T(Poly[[4,8‐bis[5‐(2‐ethylhexyl)‐2‐thienyl]benzo[1,2‐b:4,5‐b′]dithiophene‐2,6‐diyl]‐2,5‐thiophenediyl[5,7‐bis(2‐ethylhexyl)‐4,8‐dioxo‐4H,8H‐benzo[1,2‐c:4,5‐c′]dithiophene‐1,3‐diyl]]polymer):ITIC (2,2′‐[[6,6,12,12‐Tetrakis(4‐hexylphenyl)‐6,12‐dihydrodithieno[2,3‐d:2′,3′‐d′]‐s‐indaceno[1,2‐b:5,6‐b′]dithiophene‐2,8‐diyl]bis[methylidyne(3‐oxo‐1H‐indene‐2,1(3H)‐diylidene)]]bis[propanedinitrile])organic semiconductor matrix. Organic semiconductors offer advantages such as flexibility and low‐cost fabrication, but their limited X‐ray sensitivity restricts their application in radiation detection. To overcome this, hybrid active layers incorporating inorganic nanomaterials such as CdSe nanoplatelets have emerged as promising candidates for enhancing performance. The 5‐monolayer CdSe NPLs are synthesized with precise thickness control, exhibiting strong absorption and photoluminescence at 556 nm, which effectively matches the emission spectrum of CsI(Tl) scintillators. The hybrid active layer is optimized by investigating various PBDB‐T:ITIC ratios and CdSe NPLs concentrations. The optimal device configuration, achieved with a 1:1 ratio of PBDB‐T:ITIC and 1.5 mg of CdSe NPLs, demonstrates a power conversion efficiency of 7.18% and a photocurrent density of 18.74 mA/cm−2. The incorporation of CdSe NPLs enhanced the X‐ray detector's sensitivity by 31.9% compared to the pure organic device, reaching 1.86 mA/Gy cm−2. The enhanced performance is attributed to the improved light absorption and charge transport properties of the hybrid active layer, despite a slight increase in surface roughness. This work demonstrates the potential of organic–inorganic hybrid systems for next‐generation X‐ray detection applications. A hybrid semiconductor is fabricated by directly synthesizing 5ML CdSe Core into two organic semiconductors PBDB‐T:ITIC (see). The fabricated hybrid device is systematically analyzed for parameter values such as PCE, Jsc, Rs, and mobility, and corresponding TEM, AFM, XRD, etc. images are included.

The C–H bond of the methylidyne radical, CH•, is abnormally long and weak, even longer and weaker than that of methane, CH4. This is remarkable given the fact that the C–H bond has been shown to contract as the number of substituents around the pertinent carbon atom decreases (e.g., from ethane to ethene to ethyne) because of the accompanying reduction in steric congestion. To elucidate the origin of this anomaly, we have analyzed the C–H bonding mechanism of quartet CH••• and doublet CH• and compared this with the sterically more encumbered triplet CH2••, doublet CH3•, and singlet CH4, using quantitative (Kohn‐Sham) molecular orbital theory. Our analyses reveal that, depending on the effective electronic configuration of the methylidyne radical, its relatively long and weak C–H bond originates from: (i) the position at which the maximum electron‐pair bonding overlap is achieved (quartet CH•••); and (ii) the destabilizing steric Pauli repulsion between the valence orbitals on the interacting fragments (doublet CH•). Key points The C–H bond of the methylidyne radical is remarkably longer and weaker than that of the sterically more encumbered methane molecule. The position of maximum electron‐pair bonding overlap determines the long C–H bond of the methylidyne quartet CH•••. The C–H bond of the methylidyne doublet CH• expands even further, due to its effective 2s22p2 electronic configuration, yielding a significant destabilizing Pauli repulsion between the valence orbitals on the interacting fragments. Our quantum chemical analyses show that the C–H bond of the methylidyne radical is abnormally long, even longer than that of the sterically more encumbered methane molecule. This is so for both, the doublet ground state and the quartet excited state, however, for opposite reasons: (i) Pauli repulsion of the H atom with the closed‐shell carbon 2s AO; and (ii) maximum electron‐pair bonding overlap of the H atom with the carbon 2p AO a long C–H distance, respectively.

To explore the potential reactivity of the methylidyne radical (CH) toward 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), the reaction mechanism between them has been systematically investigated employing the density functional theory (DFT) and ab initio molecular dynamics simulations. The relevant thermodynamic and kinetic parameters in the possible reaction pathways have been discussed as well as the IR spectra and hyperfine coupling constants (hfcc’s) of the major products. Different from the reaction of the CH radical with 2,3,7,8-tetrachlorodibenzofuran, CH radical can attack all the C-C bonds of TCDD to form an initial intermediate barrierlessly via the cycloaddition mechanism. After then, the introduced C-H bond can be further inserted into the C-C bond of TCDD, resulting in the formation of a seven-membered ring structure. The whole reactions are favorable thermodynamically and kinetically. Moreover, the major products have been verified by ab initio molecular dynamics simulations. The distinct IR spectra and hyperfine coupling constants of the major products can provide some help for their experimental detection and identification. In addition, the reactivity of the CH radical toward the F- and Br-substituted TCDDs has also been investigated. Hopefully, the present findings can provide new insights into the reactivity of the CH radical in the transformation of TCDD-like dioxins.

Methylidyne (CH) has long been considered a reliable tracer of molecular gas in the low-to-intermediate extinction range. Although extended CH 3.3 GHz emission is commonly observed in diffuse and translucent clouds, observations in cold, dense clumps are rare. In this work, we conducted high-sensitivity CH observations toward 27 PGCCs with the Arecibo 305m telescope. Toward each source, the CH data were analyzed in conjunction with \\(^{13}\\)CO (1--0), HINSA, and H\\(_2\\) column densities. Our results revealed ubiquitous subsonic velocity dispersions of CH, in contrast to \\(^{13}\\)CO, which is predominantly supersonic. The findings suggest that subsonic CH emissions may trace dense, low-turbulent gas structures in PGCCs. To investigate environmental effects, particularly the cosmic-ray ionization rate (CRIR), we estimated CRIR upper limits from HINSA, yielding values from \\((8.1\\pm4.7)\\times10^{-18}\\) to \\((2.0\\pm0.8)\\times10^{-16}\\) s\\(^{-1}\\) (\\(N_{H_2}\\) from \\((1.7\\pm0.2)\\times10^{21}\\) to \\((3.6\\pm0.4)\\times10^{22}\\)~cm\\(^{-2}\\)). This result favors theoretical predictions of a cosmic-ray attenuation model, in which the interstellar spectra of low-energy CR protons and electrons match {\\it Voyager} measurements, although alternative models cannot yet be ruled out. The abundance of CH decreases with increasing column density, while showing a positive dependence on the CRIR, which requires atomic oxygen not heavily depleted to dominate CH destruction in PGCCs. By fitting the abundance of CH with an analytic formula, we place constraints on atomic O abundance (\\(2.4\\pm0.4\\times10^{-4}\\) with respect to total H) and C\\(^+\\) abundance (\\(7.4\\pm0.7\\times10^{13}\\zeta_2/n_{\\rm H_2}\\)). These findings indicate that CH formation is closely linked to the C\\(^+\\) abundance, regulated by cosmic-ray ionization, while other processes, such as turbulent diffusive transport, might also contribute a non-negligible effect.