Reaction Of Oxygen Atoms Research Articles

Surface reconstruction and entropy engineering of Ni(OH)2 nanosheets for enhanced electrocatalytic performances of oxygen evolution reaction in alkaline seawater

Hydrogen production via electrochemical splitting of seawater is highly desirable but still facing great challenges. Herein, we report the facile preparation of medium-entropy oxyhydroxides on Ni(OH)2 nanosheets via surface reconstruction and entropy engineering strategies, achieving enhanced electrocatalytic activity and stability for oxygen evolution reaction (OER) in alkaline seawater. The electrochemical oxidation is conducted on Ni(OH)2 nanosheets to create abundant reactive oxygen (reactive-O) atoms on the reconstructed surface, thus forming a reactive-O enriched surface on Ni(OH)2 (NiOx/Ni(OH)2). Additionally, cations are incorporated onto the reconstructed surface of NiOx/Ni(OH)2 via an electrodeposition method, forming the medium-entropy oxyhydroxides on Ni(OH)2 nanosheets ((FeCoCrNi)Ox/Ni(OH)2). Benefiting from the composition and structure advantages, the resulting (FeCoCrNi)Ox/Ni(OH)2@NF demonstrates obviously enhanced performances for OER electrocatalysis, with an overpotential of 239 mV at the current density of 10 mA cm−2 and a low Tafel slope of 24.66 mV dec−1 in 1.0 M KOH + 0.5 M NaCl solution. Furthermore, it exhibits exceptional durability for OER electrocatalysis in alkaline seawater, maintaining over 90.7 % of the OER current density after 100 h.

Kinetics and Mechanism of the Singlet Oxygen Atom Reaction with Dimethyl Ether.

We combine in situ laser spectroscopy, quantum chemistry, and kinetic calculations to study the reaction of a singlet oxygen atom with dimethyl ether. Infrared laser absorption spectroscopy and Faraday rotation spectroscopy are used for the detection and quantification of the reaction products OH, H2O, HO2, and CH2O on submillisecond time scales. Fitting temporal profiles of products with simulations using an in-house reaction mechanism allows product branching to be quantified at 30, 60, and 150 Torr. The experimentally determined product branching agrees well with master equation calculations based on electronic structure data and transition state theory. The calculations demonstrate that the dimethyl peroxide (CH3OOCH3) generated via O-insertion into the C-O bond undergoes subsequent dissociation to CH3O + CH3O through energetically favored reactions without an intrinsic barrier. This O-insertion mechanism can be important for understanding the fate of biofuels leaking into the atmosphere and for plasma-based biofuel processing technologies.

Dual electron microregion with oxygen vacancy of Fe0.8La/MCM-48 in bridging peracetic acid and ozonation: Taking the pathway of free radical or nonradical generation?

Efficient tetracycline hydrochloride (TCH) degradation and interface reaction mechanism were investigated by constructing nonradical pathways in heterogeneous peracetic acid coupling with ozonation (O3/PAA) process. Ball-milling assisted Fe–La anchoring MCM-48 catalysts with dual electron microregion was designed to trigger 1O2-dominated non-radical for strong immunity to environment interference. Results exhibited that 83.4% degradation efficiency of TCH was achieved by Fe0.8La/MCM-48/O3/PAA system in only 2 min and 94% TCH was degraded in a 12-hour continuous flow experiment. La with oxygen vacancy regulated the local atomic environment and electron structure of Fe sites, which could initiate peracetic acid activation to promote 1O2 production by surface adsorbed atomic oxygen (*Oad) reaction and this process overcame a lower reaction energy barrier than the binding of surface *Oad to O3. This work offers a reasonable interpretation for Fe–La synergy for inducing non-free radical route, which furnishes theoretical support and practical application for heterogeneous O3/PAA.

Interface reconfiguration of MnCO3/Mn3O4 heterostructure enhances the ozone decomposition in the entire humidity range

The catalytic efficiency of manganese-based catalysts in practical ozone decomposition applications is limited by challenging desorption of intermediate oxygen species and competitive adsorption of H2O molecules in humid environments. In this work, MnCO3/Mn3O4 composites with heterogeneous structures were synthesized through a facile one-step strategy. The obtained MnCO3/Mn3O4-1/2 catalyst exhibited high content of oxygen vacancies, fast electron mobility rate and obvious advantages in catalytic ozone decomposition performance at a space velocity of 600 L g−1 h−1 and 95% RH. In-situ DRIFT spectra indicated that the rate-determining steps for ozone decomposition of MnCO3 and Mn3O4 are the reaction of atomic oxygen with ozone to form O22- and desorption of O22-, respectively. MnCO3/Mn3O4 heterogeneous catalyst undergoes reconfiguration under ozone atmosphere, inducing discontinuous MnOx coatings on the MnCO3 surface, which form a potential difference with Mn3O4. MnCO3/Mn3O4 heterogeneous structure modulates the electronic state of active site, and the synergistic effect of MnCO3 and Mn3O4 improves catalytic performance.

Phosphorus adsorbed by HCl desorption–activated red mud adsorbents: a molecular dynamics studys

In this study, modified red mud after phosphorus adsorption was used as the adsorbent, and HCl and deionized water were used as desorbents to desorb phosphorus. The components in the adsorbent were optimized based on density functional theory, and adsorbent and desorbent models were established. Molecular dynamics simulation was performed to determine the phosphorus concentration before and after desorption, interaction energies, radial distribution function(RDF), mean-square displacement(MSD), and diffusion coefficient. The Monte Carlo method was used to simulate the desorption isotherm, desorption site, heat of desorption, and desorption energy. Simulation results showed that deionized water could only desorb phosphorus on the adsorbent surface, and the stability of the system deteriorated upon adding HCl. HCl destroyed the ionic and hydrogen bonding between the O atoms in H2PO4 − and reactive metal and oxygen atoms in the activated red mud particles. Moreover, the van der Waals force decreased considerably. The ionic and hydrogen bonds between H2PO4 − and the surface of activated red mud particles were broken by HCl, which accelerated the desorption of phosphorus from the adsorbent surface. The interaction between HCl and phosphorus accelerated the diffusion, which decreased the adsorption capacity. Moreover, the desorption capacity increased with increasing temperature.

Loss of Oxygen Atoms on Well-Oxidized Cobalt by Heterogeneous Surface Recombination.

Calorimetry is a commonly used method in plasma characterization, but the accuracy of the method is tied to the accuracy of the recombination coefficient, which in turn depends on a number of surface effects. Surface effects also govern the kinetics in advanced methods such as atomic layer oxidation of inorganic materials and functionalization of organic materials. The flux of the reactive oxygen atoms for the controlled oxidation of such materials depends on the recombination coefficient of materials placed into the reaction chamber, which in turn depends on the surface morphology, temperature, and pressure in the processing chamber. The recombination coefficient of a well-oxidized cobalt surface was studied systematically in a range of temperatures from 300 to 800 K and pressures from 40 to 200 Pa. The coefficient increased monotonously with decreasing pressure and increasing temperature. The lowest value was about 0.05, and the highest was about 0.30. These values were measured for cobalt foils previously oxidized with oxygen plasma at the temperature of 1300 K. The oxidation caused a rich morphology with an average roughness as deduced from atomic force images of 0.9 µm. The results were compared with literature data, and the discrepancy between results reported by different authors was explained by taking into account the peculiarities of their experimental conditions.

Understanding of the synergy effect of DBD plasma discharge combined to photocatalysis in the case of Ethylbenzene removal: Interaction between plasma reactive species and catalyst

Hybrid non-thermal plasma combined with photocatalysis is an efficient technology for the degradation of volatile organic compounds (VOCs) and leads to a synergetic boosting effect of the degradation process. Herein, the degradation of ethylbenzene (EB) in a hybrid lab-scale reactor was performed. In the combined mode (plasma DBD and photocatalysis [TiO2 + UVA]), the degradation of EB was synergetically boosted, and a higher degradation efficiency was reached. In this study, the behavior of the synergetic effect was investigated whilst varying several operational conditions, including the UV light source (UVA and UVC), the TiO2 weight (7.5–22.51 g·m-²), the addition of metallic dopants to the TiO2 at different weight ratios (x%Cu-TiO2 and x%MnO2-TiO2, where x = 1, 3, 5 and 10 for the weight ratios of Cu:TiO2 and MnO2:TiO2) and the catalyst support (glass fiber tissue [GFT] and nickel foam [NF] with different thicknesses [0.3–3.3 mm]). Moreover, the oxygen content (0–100%) in the reactor atmosphere was examined. The results showed an enhancement of the synergetic effect under UVC (TiO2 + UVC + DBD), which may be a consequence of intensive ozone decomposition under UVC and the generation of reactive atomic oxygen. The improvement of the synergetic effect under 1% Cu-TiO2 and 10% MnO2-TiO2 catalysts is assumed to reflect the role of metallic species in the production of oxygen species on the TiO2 surface via the ozone depletion mechanism. Furthermore, TiO2/NF (3.3 mm) showed the highest synergetic effect, likely due to the conductive character and the 3D porous structure of NF. Finally, the rich oxygen composition had an apparent impact on the synergetic effect.

IR Spectra of Entrance and Exit Channels of Methane Molecule and Oxygen Atom Reaction at MP2 Theory

IR spectra of entrance and exit channels of methane and radical oxygen reaction are predicted in the ground state energy. Ab initio calculations at perturbation theory (MP2) with Dunning correction- consistent basis set (aug-cc-pVDZ) have been used. The calculations predicted structures, vibrational frequencies and potential energy surface. Three van der Waals minima from three adiabatic potential energy surfaces have been predicted in entrance and exit channels. Vibration frequency of 3209 cm-1 and 3212 cm-1 of C-H stretching in entrance structures are predicted while O-H vibrational frequency is predicted to be at 3673 cm-1 in the other channel. The lowest energy structure in entrance channel has - 0.18 kJ/ mol minimum energy.

Elucidation of Molecular‐level Mechanisms of Oxygen Atom Reactions with Chlorine Ion in NaCl Solutions using Molecular Dynamics Simulations Combined with Density Functional Theory

AbstractMolecular dynamics simulations combined with density functional theory were performed to investigate the reaction mechanisms for oxygen atom and chlorine ion in NaCl solutions. Considering the ground and first excited states of the oxygen atom, four bulk systems, O(3P)‐NaCl‐63H2O, O(1D)‐NaCl‐63H2O, O(3P)‐4NaCl‐63H2O, and O(1D)‐4NaCl‐63H2O were studied. The main reaction pathway depended on the concentration of the aqueous electrolyte solution. For a dilute solution with a 1 : 64 ratio of NaCl to H2O, the singlet oxygen atom first attached a water molecule to produce a neutral OH radical, and then the OH radical and chlorine ion approach each other to form an intermediate structure [Cl…OH]−. Synchronously, the intermediate transferred charge to the solvated OH radical by accessing the hydrogen bond network. Finally, neutral HOCl and OH− ions were formed. For a dense solution with a 4 : 64 ratio of NaCl to H2O, a singlet oxygen atom was directly combined with Cl− to produce ClO− via an oxygen transfer reaction. The subsequent ab‐initio energy computations indicated the most probable mechanism, where the O atom directly combines with Cl− ion to OCl−. This study provides insights into the fundamental mechanisms of the behavior of dissolved oxygen radicals in aqueous electrolyte solutions.

Ag Anchored Atomically Around Nanopores of Porous Co(OH)2 for Efficient Bifunctional Oxygen Catalysis

AbstractVarious clean energy storage and conversion systems highly depend on rational design of efficient electrocatalysts for oxygen reactions. Increasing both gas molecular diffusion and intrinsic activity is critical to boosting its efficiency for bifunctional oxygen electrocatalysis. However, controllable synthesis of catalysts that combines gas molecular diffusion and intrinsic activity remains a fundamental challenge. Herein, a two‐step synthetic strategy is adopted to fabricate a composite oxygen reduction reaction (ORR)/oxygen evolution reaction (OER) bifunctional catalyst (P‐Ag‐Co(OH)2), of which, atomic Ag is anchored in reactive oxygen atoms around nanopores of Co(OH)2 nanosheets. Abundant nanopores provide enough gas molecular diffusion channels, and the special Ag‐O‐Co‐OH catalytic groups around nanopores display high intrinsic catalytic activity, which jointly result in an excellent ORR/OER performance. In alkaline electrolyte, P‐Ag‐Co(OH)2 displays a high half‐wave potential (0.902 V versus RHE) for ORR, and a low overpotential (235 mV at 10 mA cm−2) for OER, which is superior to non‐noble catalysts in previous studies and Pt/C (Ir/C) catalyst. At the same time, the single‐cell zinc‐air battery is prepared with an extremely high discharge peak power density of 435 mW cm−2 and excellent discharge–charge cycle stability.

Reactions O(3P, 1D) + HCCCN(X1Σ+) (Cyanoacetylene): Crossed-Beam and Theoretical Studies and Implications for the Chemistry of Extraterrestrial Environments.

Cyanoacetylene (HCCCN), the first member of the cyanopolyyne family (HCnN, where n = 3, 5, 7, ...), is of particular interest in astrochemistry being ubiquitous in space (molecular clouds, solar-type protostars, protoplanetary disks, circumstellar envelopes, and external galaxies) and also relatively abundant. It is also abundant in the upper atmosphere of Titan and comets. Since oxygen is the third most abundant element in space, after hydrogen and helium, the reaction O + HCCCN can be of relevance in the chemistry of extraterrestrial environments. Despite that, scarce information exists not only on the reactions of oxygen atoms with cyanoacetylene but with nitriles in general. Here, we report on a combined experimental and theoretical investigation of the reactions of cyanoacetylene with both ground 3P and excited 1D atomic oxygen and provide detailed information on the primary reaction products, their branching fractions (BFs), and the overall reaction mechanisms. More specifically, the reactions of O(3P, 1D) with HCCCN(X1Σ+) have been investigated under single-collision conditions by the crossed molecular beams scattering method with mass spectrometric detection and time-of-flight analysis at the collision energy, Ec, of 31.1 kJ/mol. From product angular and time-of-flight distributions, we have identified the primary reaction products and determined their branching fractions (BFs). Theoretical calculations of the relevant triplet and singlet potential energy surfaces (PESs) were performed to assist the interpretation of the experimental results and clarify the reaction mechanism. Adiabatic statistical calculations of product BFs for the decomposition of the main triplet and singlet intermediates have also been carried out. Merging together the experimental and theoretical results, we conclude that the O(3P) reaction is characterized by a minor adiabatic channel leading to OCCCN (cyanoketyl) + H (experimental BF = 0.10 ± 0.05), while the dominant channel (BF = 0.90 ± 0.05) occurs via intersystem crossing to the underlying singlet PES and leads to formation of 1HCCN (cyanomethylene) + CO. The O(1D) reaction is characterized by the same two channels, with the relative CO/H yield being slightly larger. Considering the recorded reactive signal and the calculated entrance barrier, we estimate that the rate coefficient for reaction O(3P) + HC3N at 300 K is in the 10-12 cm3 molec-1 s-1 range. Our results are expected to be useful to improve astrochemical and photochemical models. In addition, they are also relevant in combustion chemistry, because the thermal decomposition of pyrrolic and pyridinic structures present in fuel-bound nitrogen generates many nitrogen-bearing compounds, including cyanoacetylene.

Reactions of oxygen atoms with fluoroform and its radiolysis products: matrix isolation and ab initio study.

The investigation of the reactions of oxygen atoms with fluoroform (CHF3) molecules and products of their degradation present significant interest for better understanding of the impact of chemically inert fluorinated compounds on atmospheric chemistry and may provide a deeper insight into mechanisms of chemical processes occurring under the action of hard UV and ionizing radiation. In the present study we applied a matrix isolation technique with FTIR spectroscopic detection combined with ab initio calculations to address this issue. It was found that the reactions of "hot" (translationally excited) O(1D) atoms produced by X-ray or UV radiation from appropriate precursors (N2O or H2O) resulted in the formation of carbonyl fluoride (COF2) and its complex with HF. The complex was detected and characterized for the first time. Singlet oxygen atoms also probably react with the products of radiation-induced degradation of fluoroform (CF3 and CF2). Additionally, the reaction of "hot" O(3P) atoms with fluoroform may occur to a certain extent yielding the CF3 radical. No evidence for the reactions of thermal O(3P) atoms with CHF3 or products of its degradation was found under the experimental conditions used. The implications of the results of this model study for understanding the evolution of fluoroform in the upper layers of the stratosphere and ionosphere are discussed.

Performance and mechanism study of Ce2(SO4)3 for methane chemical looping partial oxidation

Partially oxidizing methane into syngas via a two-step chemical looping scheme was a promising option for methane transformation. Ce2(SO4)3 was selected to explore the performance and mechanism of methane chemical looping partial oxidation (CLPOM) to syngas. Thermodynamic and kinetic analysis forecast the Ce2(SO4)3 as a promising candidate for CLPOM. Compared with literature, Ce2(SO4)3 not only had an outstanding syngas selectivity, but also an appropriate CH4 conversion and molar ratio, and CH4 conversion could reach 90.5 % of thermodynamic result. As revealed via characterization, Ce2(SO4)3(102) surface had the highest peak intensity and the migration of lattice oxygen played an important role in CLPOM. Some of them were tend to agglomeration and these small particles were less than 5 μm. Density functional theory calculations demonstrated that CH4 series dehydrogenation products tended to adsorb at O site and CH3 → CH2 + H was the rate-determining step. The reaction of surface lattice oxygen atoms and migration of the internal lattice oxygen atoms could inhibit carbon deposition, promote CH4 conversion and syngas generation in experiment. Compared with NiO, Ce2(SO4)3 had a lower energy barrier of lattice oxygen migration, which could increase the reaction rate.

Diabatic potential energy surfaces and semiclassical multi-state dynamics for fourteen coupled 3 A′ states of O3

Dissociation and energy transfer in high-energy collisions of O2 play important roles in simulating thermal energy content and heat flux in flows around hypersonic vehicles. Furthermore, atomic oxygen reactions on the vehicle surface are an important contributor to heat shield erosion. Molecular dynamics modeling is needed to better understand the relevant rate processes. Because it is necessary to model the gas flows in high-temperature shock waves, electronically excited states of O2 and O can be populated, and molecular dynamics simulations should include collisions of electronically excited species and electronically nonadiabatic collisions. This requires potential energy surfaces and state couplings for many energetically accessible electronic states. Here we report a systematic strategy to calculate such surfaces and couplings. We have applied this method to the fourteen lowest-energy potential energy surfaces in the 3 A′ manifold of O3, and we report a neural-network fit to diabatic potential energy matrix (DPEM). We illustrate the use of the resulting DPEM by carrying out semiclassical dynamics calculations of cross sections for excitation of O2 in 3 A′ collisions with O at two collision energies; these dynamics calculations are carried out by the curvature-driven coherent switching with decay of mixing method.

Stability of Wafer-Scale Thin Films of Vertically Aligned Hexagonal BN Nanosheets Exposed to High-Energy Ions and Reactive Atomic Oxygen.

Stability of advanced functional materials subjected to extreme conditions involving ion bombardment, radiation, or reactive chemicals is crucial for diverse applications. Here we demonstrate the excellent stability of wafer-scale thin films of vertically aligned hexagonal BN nanosheets (hBNNS) exposed to high-energy ions and reactive atomic oxygen representative of extreme conditions in space exploration and other applications. The hBNNS are fabricated catalyst-free on wafer-scale silicon, stainless steel, copper and glass panels at a lower temperature of 400 °C by inductively coupled plasma (ICP) assisted chemical vapor deposition (CVD) and subsequently characterized. The resistance of BNNS to high-energy ions was tested by immersing the samples into the plasma plume at the anode of a 150 W Hall Effect Thruster with BNNS films facing Xenon ions, revealing that the etching rate of BNNS is 20 times less than for a single-crystalline silicon wafer. Additionally, using O2/Ar/H2 plasmas to simulate the low Earth orbit (LEO) environment, it is demonstrated that the simulated plasma had very weak influence on the hBNNS surface structure and thickness. These results validate the strong potential of BNNS films for applications as protective, thermally conductive and insulating layers for spacecrafts, electric plasma satellite thrusters and semiconductor optoelectronic devices.

Effect of ozone addition and ozonolysis reaction on the detonation properties of C2H4/O2/Ar mixtures

Ozone is one of the strongest oxidizers and can be used to enhance detonation. Detonation enhancement by ozone addition is usually attributed to the ozone decomposition reaction which produces reactive atomic oxygen and thereby accelerates the chain branching reaction. Recently, ozonolysis reaction has been found to be another mechanism to enhance combustion for unsaturated hydrocarbons at low temperatures. In this study, the effects of ozone addition and ozonolysis reaction on steady detonation structure and transient detonation initiation and propagation processes in C2H4/O2/O3/Ar mixtures are examined through simulations considering detailed chemistry. Specifically, the homogeneous ignition process, the ZND detonation structure, the transient direct detonation initiation, and pulsating instability of one-dimensional detonation propagation are investigated. It is found that the homogenous ignition process consists of two stages and the first stage is caused by ozonolysis reactions which consume O3 and produces CH2O as well as H and OH radicals. The ozonolysis reaction and ozone decomposition reaction can both reduce the induction length though they have little influence on the Chapman–Jouguet (CJ) detonation speed. The supercritical, critical and subcritical regimes for direct detonation initiation are identified by continuously decreasing the initiation energy or changing the amount of ozone addition. It is found that direct detonation initiation becomes easier at larger amount of ozone addition and/or larger reaction progress variable. This is interpreted based on the change of the induction length of the ZND detonation structure. Furthermore, it is demonstrated that the ozonolysis reaction can reduce pulsating instability and make the one-dimensional detonation propagation more stable. This is mainly due to the reduction in activation energy caused by ozone addition and/or ozonolysis reaction. This work shows that both ozone decomposition reaction and ozonolysis reaction can enhance detonation for unsaturated hydrocarbon fuels.

Simple cleaning and regeneration of tip‐enhanced Raman spectroscopy probe with UV sources

AbstractTip‐enhanced Raman spectroscopy (TERS) is a powerful nano‐optical approach that allows the extraction of nanometer resolved chemical information. The key to a successful TERS measurement is the quality of the TERS tip. However, tip contamination, which usually occurs during measurements on samples that include organic molecules or after long‐term storage, remains a critical problem for TERS experiments. It not only affects the reliability of TERS results but also hinders the long‐term development of the TERS technique. Herein, we propose a method that enables the regeneration of contaminated TERS tips. For this purpose, we prepared a TERS tip contaminated by stable organic molecules, which was subjected to a simple and rapid ultraviolet (UV) cleaning procedure to remove the contaminants and to regenerate the tip. This method is demonstrated to be effective in removing the contaminants from the TERS tip by directly breaking the bonds in the contaminated molecules and oxidizing organic compounds with the generated reactive oxygen atom. This simple method could propel the development of the TERS technique.

Interfacial dependent reactive oxygen species generation over Pt-ZrO2 nanoparticles for catalytic oxidation of formaldehyde at room temperature

Producing the strong metal-support interaction (SMSI) interface and highly reactive oxygen species is a great challenge for catalytic oxidation of formaldehyde (HCHO) at room temperature over supported metal catalysts. Herein, we report a conceptual oxygen vacancy (VO) associated SMSI interface of Pt-ZrO2 nanoparticles for HCHO catalysis at room temperature, exhibiting interfacial dependent reactive oxygen species (O*) formation. The VO on the ZrO2 support captures and activates the molecular O2, then proceeds to generating the reactive oxygen atom (O*) with a lower activation barrier of 0.3 eV. The generated O* tends to link the (110) surface of ZrO2 and the (111) surface of Pt as an electronic transmission channel for the selective catalytic oxidation of HCHO adsorbed on the (110) surface of ZrO2, accelerating the direct generation of formate species and mineralization of HCHO. The Pt-VO-ZrO2 achieves high HCHO removal and HCHO conversion (>95%) at 20 °C. These findings will consolidate the fundamental theories of room temperature catalytic reactions via constructing the SMSI interface engineering for wide environmental applications.

Rate constant and products of the reaction of O(3P) atoms with thiirane over the temperature range 220–950 K

AbstractA discharge‐flow modulated molecular beam mass spectrometry technique has been used to determine the rate constant for the reaction of ground state oxygen atoms with C2H4S in the temperature range 220–950 K. The reaction rate constant has been determined directly by monitoring C2H4S in an excess of O atoms and through competitive reaction of oxygen atoms with C2H4S and Br2. Weak, negative temperature dependence is observed below 300 K, whereas positive temperature dependence is observed above 380 K: k = 1.13 × 10–12 (T/298)2.18 exp(733/T) cm3 molecule–1 s–1. We estimate this expression to be accurate within 15% over the investigated temperature range. SO and C2H4 have been detected as reaction products and a branching ratio of unity (with uncertainty of 10%) has been found for the channel forming these two species in the temperature range 300–900 K, confirming that the title reaction is an efficient source of SO radicals.

Gas-Phase Preparation of Subvalent Germanium Monoxide (GeO, X1Σ+) via Non-Adiabatic Reaction Dynamics in the Exit Channel.

The subvalent germanium monoxide (GeO, X1Σ+) molecule has been prepared via the elementary reaction of atomic germanium (Ge, 3Pj) and molecular oxygen (O2, X3Σg-) with each reactant in its electronic ground state by means of single-collision conditions. The merging of electronic structure calculations with crossed beam experiments suggests that the formation of germanium monoxide (GeO, X1Σ+) commences on the singlet surface through unimolecular decomposition of a linear singlet collision complex (GeOO, i1, C∞v, 1Σ+) via intersystem crossing (ISC) yielding nearly exclusively germanium monoxide (GeO, X1Σ+) along with atomic oxygen in its electronic ground state [p1, O(3P)]. These results provide a sophisticated reaction mechanism of the germanium-oxygen system and demonstrate the efficient "heavy atom effect" of germanium in ISC yielding (nearly) exclusive singlet germanium monoxide and triplet atomic oxygen compared to similar systems (carbon dioxide and dinitrogen monoxide), in which non-adiabatic reaction dynamics represent only minor channels.