Physics

Two-dimensional (2D) materials with ultralow lattice thermal conductivity (kl) are crucial for high-efficiency thermoelectrics. Herein, we investigate the thermal transport properties of monolayer CdIn2Se4 using first-principles calculations combined with the phonon Boltzmann transport equation. An exceptionally low kl of 0.28 W m−1 K−1 is predicted at 300 K. This ultralow kl originates from the synergistic effect of strong lattice anharmonicity and weakened chemical bonds. The strong anharmonicity induces intense phonon scattering, and an extremely strong intraband and interband scattering in the out-of-plane acoustic branch is identified beyond expectation, leading to extremely short phonon relaxation times. Chemical bonding analysis reveals that the filling of antibonding states below the Fermi level weakens the Se–Cd bonds, which significantly reduces the phonon group velocities. Further scattering channel analysis confirms that the strong acoustic–acoustic and acoustic–optical phonon scatterings are the key factors suppressing kl. Our findings not only pinpoint the dual origins of ultralow kl in a promising 2D thermoelectric material but also provide a mechanistic framework for designing materials with engineered thermal transport properties.

From the definitions of parameters of thermionic electron emission, theories of insulators and semiconductors (IS) and field emission, and those of the escape of electron-induced internal secondary electrons (EIISE), the formulas for j, G, EAve, and B of IS and semiconductors with high-density surface energy states (SHS) were deduced, respectively. Here, j, G, and EAve denote the current density, spectrum, and average energy of hot electrons, respectively; B is the average probability that a hot electron escapes into vacuum upon reaching the surface. The deduced formulas were analyzed and compared with existing results. It is concluded that the deduced formulas for j of IS and SHS are theoretically correct, and that the formulas for G, EAve, and B derived here can express those quantities for IS and SHS, respectively. From the definition of Bs and the fact that, when the absolute temperature in the formula for G is taken as a given value, the deduced G of IS can express the spectra of secondary electrons from IS, the formula for Bs and a more accurate method for calculating Bs were deduced and presented, respectively. Here, Bs denotes the mean escape probability of EIISE reaching the emission surface of IS. The method for calculating ΔQ using the formula for j of SHS derived here was presented, where ΔQ is the quantity of band bending due to high-density surface energy states of semiconductors. The two presented methods were analyzed, and it is concluded that they are correct.

Modeling the single Shockley stacking fault (1SSF) in 4H-silicon carbide as a classical well built in the bottom of the conduction band, technical computer-aided design simulations were conducted rigorously incorporating carrier recombination at the 1SSF. The experimentally observed temperature dependences of the critical photoexcitation intensity for 1SSF expansion can be reproduced only if the radiative recombination coefficient in the 1SSF at room temperature is enhanced by a factor of about 103 times larger than the value in the matrix. The primary cause of energy reduction Δγ due to the presence of the 1SSF is such enhanced carrier recombination in the 1SSF. However, the main contribution to Δγ arises from the reduction in electronic energy in the perfect matrix surrounding the 1SSF over the range of minority carrier diffusion length. This provides another reason why 1SSF expansion is suppressed by the reduction in carrier lifetime. The cause of the apparent discrepancy of experimentally evaluated γ1SSF, the formation energy of the 1SSF in thermo-equilibrium, between n- and p-type samples obtained in mechanical stressing experiments can be attributed to the nonlinear dependence of Δγ on the electron–hole generation rate in the low-injection regime and the inherent difference in the degree of the nonlinearity between n- and p-type samples. The value of γ1SSF is considered to be closer to 7.9 ± 1.3 mJ/m2, which is experimentally deduced in p-type samples.

Mechanical stressing experiments devised to evaluate the formation energy of a single Shockley stacking fault (1SSF) γ1SSF have been conducted with the use of photoluminescence imaging of partial dislocations bounding 1SSFs in various 4H-SiC epilayers. Elaborate care was taken to avoid the blocking effect of point obstacles on the glide motion of partial dislocations that enables expansion and contraction of the 1SSFs. Analysis of the experimental results appears to show apparently different values of γ1SSF between n-type and p-type samples. Conversely, the critical ultraviolet light intensity that demarcates 1SSF expansion and contraction showed a similar temperature dependence for n-type and p-type samples.

Biocatalytic generation of reactive oxygen species (ROS) by artificial enzymes offers a promising strategy for treating diverse diseases, including pathogenic infections and malignancies. However, the sluggish ROS biocatalytic efficiency and unstable active sites have hindered their potential clinical translation. Here, inspired by natural vanadium haloperoxidases and NADPH oxidase-based ROS-catalytic systems, we report the de novo design of a sono-activated artificial vanadium enzyme (V^x+-SonoAE) for efficient and renewable ROS nanobiocatalytic therapies. By mimicking the electron transport chains and active VO₄ centers in natural enzymes, our innovative bionic approach not only yields efficient, robust, and precise vanadium active sites on TiO₂ but also enables continuous regeneration of redox centers during ROS biocatalysis via efficient electron transfer from sono-activated TiO₂ to the V^x+ site. Consequently, the V^x+-SonoAE achieves remarkable ROS-catalytic performance with a superior turnover number (TON = 54 × 10^-3 s^-1) that far surpasses the reported state-of-the-art metal oxides-based nanobiocatalysts. Moreover, this new artificial enzyme system demonstrates exceptional therapeutic efficiency in infection control and tumor regression with sustained and sono-activated treatment properties. This work establishes a new paradigm for designing efficient and renewable nanobiocatalysts, combining fundamental insights from natural enzymatic systems with advanced materials engineering to create robust therapeutic platforms with long-term efficacy.

Rapid breakthroughs in IoT and AI have raised demand for portable, self-powered, flexible sensor devices. Hydrogels with high conductivity, mechanical tunability, environmental adaptability, and biocompatibility are a clever way to develop flexible sensors for triboelectric nanogenerators. TENG application is limited by the paucity of suitable biomaterials and the need for highly conductive fillers such 2D materials, which trade off transparency, output, and sensing. A unique, very transparent, highly stretchable, high-output performance biomimetic stevia/PVA hydrogel-based triboelectric nanogenerator (S-TENG) is investigated to overcome this issue. Due to its abundant dynamic hydrogen bonding, cost-effective biomimetic stevia is added to polyvinyl alcohol (PVA) to increase hydrogel cross-linking and crystalline domains. These structural advancements give the S-hydrogel 2-5 times the mechanical strength and 3-8 times the electrical output of 2D-, bio-, and transparent-material-based TENGs, while maintaining transparency. The S-hydrogel may be recycled and recovered by water-assisted dissolution and re-gelation, keeping its voltage output. The improved S-TENG is a self-powered sensor for various human motions with great sensitivity and a 13-ms reaction time. The XGBoost method had the greatest classification accuracy of 95.29% among eleven machine learning models, showing the promise of self-powered sensors for many applications.

Vanadium oxides have emerged as attractive cathode materials for zinc-based batteries owing to their high theoretical capacity and versatile redox chemistry. Nevertheless, their persistent dissolution in aqueous electrolytes remains a long-standing challenge, hindering real-world implementation. Here, we develop a cation-engineered electrolyte strategy enabled by a data-driven framework that integrates density functional theory (DFT) calculations, discrete wavelet transform (DWT)-based multi-scale analysis, and differential feature extraction, to efficiently screen potential hetero-cations and their combinations with objective statistic quantification, while minimizing trial-and-error experimentation and selection bias. As a proof of concept, the Zn/VOx batteries with the predicted Na⁺-Mg²⁺-Zn²⁺ tri-cation electrolyte (NMZ) achieved exceptional reversibility and record-long cycling stability, sustaining 500 cycles at 0.2 A g^-1 (1400 h) and 10,000 cycles at 5 A g^-1. The tri-cation electrolyte successfully triggers a potential-driven sequential ion insertion pathway involving Na⁺, Mg²⁺, and Zn²⁺, thereby fundamentally suppressing proton intercalation above 1.3 V and hydrated Zn²⁺ insertion near 1.0 V (vs Zn²⁺/Zn). This work not only provides valuable data-driven insights into ion-engineering electrochemistry for regulating insertion stability but also uncovers critical ion-related factors that are frequently overlooked. This approach establishes a reusable and statistically robust framework for guiding research across diverse battery chemistries.

Terahertz (THz) spectroscopy, a label-free and noninvasive tool that is used to resolve the characteristic information of biomolecules, has attracted extensive attention in both physics and biochemistry. However, the traditional THz time-domain spectroscopy (THz-TDS) systems are constrained by linear polarization, disregarding the analyte chirality information that is vital for conducting biomedical analyses in the food and pharmaceutical industries. Here, we develop a technique called THz eigenmode-fingerprint chiroptical spectroscopy (TEFCS) on an achiral gradient metasurface (AGM) platform, enabling the unambiguous resolution of heterogeneous chiral biomolecule mixtures (constituents, chiralities, and ratios). The THz chiral phonon signals can be spectrally consistent and significantly enhanced due to the optimized spectral overlap between the broadband AGM resonances and the biomolecule chiral phonons, resulting in augmented eigen circular dichroism (CD) spectra. The enhanced photon‒phonon coupling scheme in the AGM‒biomolecule system is understood via the anisotropic coupled oscillator theory and gives rise to a substantial sensitivity improvement. These findings provide new insights into integrated bioanalyses and pharmaceutical applications.

It is a well-established fact that the energetic offset between the donor and the acceptor components in organic solar cells dictates the tradeoff between photovoltage and photocurrent losses. Yet, a deeper understanding of the photophysical processes that ultimately limit photocurrent generation in low offset blends is needed for more informed future molecular and device design. This Perspective addresses the most important issues surrounding this topic, from the difficulty of accurately determining state energies and driving forces to bottlenecks in free-charge generation arising from low energy offsets. Using experimental, analytical, and theoretical evidence, we then substantiate our view that the primary-if not the sole-cause of photocurrent losses in low offset non-fullerene acceptor blends is the decay of excitons that did not undergo charge transfer. We conclude that the offset between the local exciton and the interfacial charge transfer state must be at least 100 meV, which translates into a frontier orbital offset of approximately 300 meV, similar to what has been proposed for fullerene-based blends. We discuss the relevance of this finding with regard to the non-radiative voltage loss of current high-performance solar cells, and what measures should be taken to reduce this loss without impairing photovoltaic power generation.

Modulating catalytic reaction pathways and site reaction behaviors to break the activity/stability trade-off poses significant challenges for the acid oxygen evolution reaction (OER). Herein, a sol-gel method is proposed to prepare high entropy rare earth (HERE) perovskite oxides HERECoO₃/RuO₂ (RE = La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu) for pH-universal OER for the first time. (LaPrNdSmEu)CoO₃/RuO₂ achieves a current density of 10 mA cm^-2 for OER with overpotentials of only 115 mV and operates stably over 1000 h at 0.1 A cm^-2 under the acidic condition. Experimental results indicate that the novel spin regulation-lattice oxygen mechanism (SR-LOM) induces a shift in the OER mechanism from the adsorption evolution mechanism (AEM) to LOM, and promotes the spin state transition of Co to optimize intermediate adsorption. Theoretical calculations have confirmed that the high entropy strategy has induced stronger interactions at the heterointerface, which not only accelerates the electron transfer but also promotes the electroactivity of the surface. Moreover, the lattice oxygen becomes more flexible in HERECO₃/RuO₂, enabling the LOM process to promote the superior OER with reduced energy barriers. Our findings provide a new way for the rational design of highly active RE-based electrocatalysts.

Direct arylation polycondensations (DArP), including the DArP of C─Br and C─H monomers and oxidative DArP of C─H monomer(s), are characterized by their atom economy and simplicity compared with conventional transition-metal-catalyzed polycondensations. In the past decade, DArP have emerged as promising protocols for synthesizing high-performance polymer semiconductors used in organic thin-film transistors (OTFTs), organic solar cells (OSCs), organic electrochemical transistors (OECTs), etc. Several existing high-performance polymer semiconductors with high molecular weight and low structural defects have been successfully synthesized via optimizing the polymerization conditions of C─Br/C─H DArP, achieving device performances comparable to or even exceeding the counterparts obtained from conventional methods. Particularly, new C─H monomers, such as β-halogenated thiophene derivatives and 5-thiazoyl-terminated aryls, have been designed with consideration of both the enhancement of C─H-bond reactivity and semiconducting properties of the resulting polymers, enabling the synthesis of novel conjugated polymers with superior semiconducting properties via DArP as efficient as conventional protocols such as Stille and Suzuki polycondensations. In this article, we summarize the progress in high-performance polymer semiconductors synthesized via DArP as mentioned above and discuss mechanistic insights underlying the improved polymerization outcomes.

Wavelength-selective photodetectors are essential for applications such as hyperspectral imaging, biomedical diagnostics, and secure optical communication. Conventional photodetection systems typically rely on external filters or post-processing to resolve spectral information, leading to increased system complexity and data transfer overhead. Here, we report a reconfigurable photodiode based on spatially patterned doped tungsten diselenide (WSe₂), which exhibits two runtime switchable photodetection modes and a bidirectional wavelength-dependent conductance modulation across the visible spectrum. Under a broadband photodetection mode, the device exhibited a fast response and a high linear dynamic range of 72 dB. Meanwhile, under color-filtering mode, the device enables nonvolatile and color-selective detection spanning from 445 to 780 nm, to experimentally achieve the in-sensor spectral processing, including color-based logic operations and object trajectory recognition within the visible wavelength range. We further demonstrate its application in encrypted information identification using chromatically encoded digit patterns, where the device selectively decodes multicolor information via bias-controlled readout. Simulation results confirm high classification accuracies of approximately 98.99% for red and 98.76% for green patterns using a standard convolutional neural network, highlighting the potential of this platform for hardware-level spectral-domain information processing with reduced system complexity.

G-quadruplex hydrogels hold great promise for biofabrication owing to their dynamic supramolecular nature, provided their inherent instability under physiological conditions is overcome. Here, a bioinspired strategy that synergistically combines supramolecular self-assembly, under macromolecular crowding conditions, with in-bath enzymatic covalent crosslinking was employed to create stable, protein-based G-quadruplex-derived hydrogels. Mimicking the crowded intracellular milieu, the addition of Ficoll enhances G-quadruplex stability and tunes the rheological behavior, while transglutaminase-mediated crosslinking reinforces the network, preserving its structural integrity over extended periods. This combined approach yields printable bioinks with optimal viscosity, yield stress, and shear-thinning properties, enabling the fabrication of complex, multilayered 3D constructs that support enhanced cell viability and proliferation within an extracellular matrix (ECM)-mimetic fibrillar environment. Moreover, the modulation of the crosslinking density allows controlling cellular responses, offering a versatile platform for tailoring the biomechanical microenvironment. This study establishes a new class of hybrid G-quadruplex hydrogel bioinks, exhibiting unprecedented stability under physiological conditions, biofunctionality, and off-the-shelf availability, unlocking their potential for advanced tissue engineering and regenerative medicine strategies.

Asymmetric nanostructured materials are of significant interest due to their unique physicochemical properties and promising applications. However, the one-step synthesis of hierarchical asymmetric architectures with precisely controlled morphology and high-curvature interfaces remains challenging. Here, we propose a solvent-driven dissolution-regrowth-migration (SDM) strategy that directs the growth of phenolic resin and regulates the water-oil interface, enabling the one-pot fabrication of asymmetric polymeric and carbon nanoparticles consisting of a mesoporous nanosphere "head" and highly curved lamellar nanosheet "tail". This SDM process integrates bottom-up self-assembly with top-down selective etching and repolymerization, achieving an "internal-external synergy" that precisely tailors the surface migration process and asymmetric nanoarchitecture by simply tuning the ethanol content. The asymmetric carbon electrocatalyst, ACN-PdCu, possesses a higher specific surface area, uniformly dispersed PdCu alloy phases, and an elevated Cu⁰/Cu^δ ⁺ ratio compared with conventional symmetric nanoparticles. Finite-element simulations and theoretical calculations uncover that this asymmetric architecture enhances local mass diffusion, strengthens substrate adsorption and activation, as well as facilitates charge transfer, thereby improving overall catalytic performance toward the electrocatalytic semihydrogenation of 3-butyne-1-ol, achieving >92% conversion and >98% selectivity to 3-butene-1-ol, along with excellent cycling stability. The SDM strategy opens a new avenue for designing asymmetric architectures and advanced functional materials with enhanced catalytic activities.

Cr₂Ge₂Te₆, a prototypical van der Waals (vdW) ferromagnetic semiconductor, has attracted significant interest for its potential applications in high-performance spintronics. However, the magnetic ground state of monolayer Cr₂Ge₂Te₆ remains elusive due to fragile and irregularly shaped thin flake samples with weak magnetic signals. Here, we successfully grow Cr₂Ge₂Te₆ films down to one monolayer by molecular beam epitaxy. By exploiting a self-limiting growth mode, we achieve uniform monolayer Cr₂Ge₂Te₆ films across entire millimeter-scale Si substrates. Through a combination of superconducting quantum interference device magnetometry and anomalous Hall effect measurements, we establish that monolayer Cr₂Ge₂Te₆ exhibits intrinsic ferromagnetism with perpendicular magnetic anisotropy below 10 K, albeit with strong magnetic fluctuations characteristic of its 2D nature. Furthermore, a systematic thickness-dependent study reveals that a crossover from this fluctuation-dominated 2D magnetism turns into conventional long-range ferromagnetic order as the film thickness increases. Our work not only definitively establishes the intrinsic ferromagnetic ground state of monolayer Cr₂Ge₂Te₆, but also provides a scalable, silicon-compatible route for preparing the 2D magnet for future spintronic or quantum devices.

Abstract A physics-based parameterization of the critical current as a function of magnetic field and temperature ( I c ( B , T )) has been developed for multi-filamentary, low AC-loss, high current-density ( J c ) Bi 2 Sr 2 CaCu 2 O 8+x (Bi-2212) superconducting round wire. The parameterization was developed using I c ( B , T ) data that were measured in applied magnetic fields 0 ≤ B ≤ 8 T, and in temperatures 4.2 ≤ T ≤ 65 K, and is valid across the entire measurement range. The parameterization uses a tri-exponential decay of the critical current with increasing magnetic field, highlighting three distinct current-paths through the polycrystalline material: One for strongly connected grains, and two for weakly connected grains, which are most likely directly related to three sets of c -axis grain-misalignment angles. Such analyses therefore enable probing of the internal grain-connectivity from a common 4-point I c -measurement. An accurate description of I c( B , T ) across the functional field-temperature parameter-space is furthermore critical for application design, which requires reliable parameterizations.

Nanoporous zinc oxide (ZnO) thin films have attracted considerable attention and are widely used in advanced photonic and chemical applications. Although various methods exist for producing large area nanoporous ZnO thin films, they often require complex, costly equipment, and a simple one-pot synthesis is still lacking. Developing a simple and accessible fabrication method would therefore facilitate and broaden their application in optoelectronics, photocatalysis, and as templates for advanced functional materials, including metal–organic frameworks (MOFs). In this study, we report an approach for fabricating large-area nanoporous ZnO thin films using lyotropic liquid crystals (LLCs) as templates, which are subsequently converted into microporous ZIF-8 films, enabling the observation of pronounced Fano resonances in J-aggregate coated ZIF-8 films. The nanoporous ZnO thin films were prepared using a hexagonal LLC phase composed of a metal ion source Zn(NO3)2·6H2O, a nonionic surfactant C12E10, and water. Calcination at 450 °C yielded nanoporous ZnO films, which were subsequently converted into localized ZIF-8 crystals and uniformly coated with J-aggregate dyes, enabling the observation of Fano resonances and highlighting their strong potential for photonic applications. Therefore, we propose that microporous ZIF-8 crystals, with their porous structure and the localization of the electromagnetic field within them, serve as an ideal dielectric platform for studying light–matter interactions in the weak coupling regime.

Carbon dots (CDs) are fluorescent nanoparticles whose success stems from accessible bottom-up synthetic methodologies, using readily available substrates as precursors. Despite considerable interest in CDs, uncertainty surrounds their luminescence origin as molecular fluorophores (MFs) formed during thermal treatment may be the true source of fluorescence. The realization that MFs coexist with CD formation has intensified focus on purification protocols, yet reaction conditions have remained comparatively neglected due to the extensive parameter space. In this work, the synthetic conditions governing CD formation were systematically investigated. Ubiquitous citric acid (CA) and ethylenediamine (EDA) served as our carbon and nitrogen sources, respectively. Both hydrothermal and microwave heating methodologies were employed. The resultant products were subjected to meticulous examination, with particular emphasis upon their fluorescence properties, quantified through quantum yield measurements, and their size distributions, assessed via high-pressure size exclusion chromatography. Machine learning algorithms were employed to establish correlations between synthesis parameters and the size and fluorescence characteristics of the resultant products. Reaction mixtures of CA/EDA 1:1 at pH 8.5, subjected to microwave heating at 205 °C for 25 min, yield predominantly MFs, whereas reaction mixtures of CA/EDA 1:2 at pH 4.5, subjected to hydrothermal treatment at 260 °C for 15 h, yield CDs. Beyond furnishing guidance for tuning reactions toward either MF or CD formation, these findings permit elucidation of the underlying synthetic mechanisms: mildly acidic conditions favor polymerization and subsequent carbonization into CDs at elevated temperatures, while mildly basic conditions impede reactivity, arresting the synthetic pathway at the molecular level.

Novel two-dimensional nanomaterials have attracted broad interest for both fundamental physics and next-generation device applications because the atomic-layer limit gives rise to properties that are absent in their bulk counterparts. However, conventional approaches for synthesizing atomically thin metals and related non-van der Waals materials are often limited by small lateral dimensions, poor coverage uniformity, and insufficient air stability. Epitaxial graphene on silicon carbide (EG/SiC) serves as a powerful platform for confining metals at the interface to realize large-area, monolayer-to-few-layer, air-stable metals, metal alloys, and metal compounds. In this review, we discuss the mechanisms governing intercalant-layer formation from both experimental and theoretical perspectives, as well as the characterization techniques used to verify intercalation and resolve interfacial superstructures, including low-energy electron diffraction, scanning tunneling microscopy, x-ray photoelectron spectroscopy, Raman spectroscopy, and microscopy methods. Enabled by atomic-scale confinement and the unique asymmetric environment of the host interface, these EG/SiC systems exhibit a range of emergent properties, including metal-to-semiconductor transitions, superconductivity, spin–orbit-related phenomena, and two-dimensional magnetic properties. Finally, recent processing advances toward future device applications and direct epitaxial heterostructures are discussed.

Kinetic Monte Carlo simulations were combined with Bayesian optimization to identify the kinetic conditions that favor compact early-stage Na deposition on Cu at room temperature. Rather than specifying all parameters from electronic-structure inputs, we adopt a morphology-first strategy in which only the dominant kinetic terms—overpotential, terrace diffusion, and lateral binding—are varied within literature-motivated bounds. Bayesian optimization provides a data-efficient means of exploring this reduced parameter space, while ensemble averaging yields a statistically stable kinetic optimum. Under the identified conditions, Na growth at two monolayers remains laterally continuous and quasi-layer-by-layer, with minimal roughness relative to nearby parameter combinations within the explored kinetic landscape. Phase-map analyses reveal a narrow compact-growth basin surrounded by increasingly rough morphologies at high driving forces or reduced mobility. Skewness serves as a supporting diagnostic, highlighting an early-time asymmetry regime at very low-magnitude overpotentials, while roughness remains the most reliable indicator of compact growth. Although motivated by Na/Cu electrodeposition, this combined Kinetic Monte Carlo and Bayesian optimization framework offers a general, data-efficient approach for locating kinetic regimes consistent with smooth alkali-metal electrodeposition.

Within the plethora of different vanadium oxide phases, vanadium dioxide (VO2) is a well-studied material for thermochromic applications such as smart windows. To obtain crystalline VO2 thin films, usually high in situ substrate temperatures are necessary. This, in turn, is detrimental on industrial scales, hence, alternatively postgrowth temperature treatment is a viable option. Even so, the surface morphology and roughness of the thin films exhibit strong temperature dependence. As these characteristics directly govern the physical, optical, and electronic responses, precise control of surface morphology—while maintaining phase stability—is vital. This is even more critical in multilayer architectures, where surface morphology influences the multilayer’s interfaces. Here, we use ion-beam sputter deposition for the reproducible growth of vanadium oxide and assess a variety of annealing procedures to manipulate both the surface and phase of the material. We show that the surface morphology as well as the phase transition depend on the annealing parameters, such as atmosphere, pressure, temperature, and duration of the chosen treatment.

In order to elucidate the radical recombination process on solid surfaces, which is composed of radical adsorption, associative reaction of adsorbates, and desorption of products, oxygen (O)-atom adsorption on quartz, stainless-steel (SS), and alumina surfaces was directly evaluated with a molecular beam scattering technique using a plasma-driven beam source. O-atoms were generated through the plasma decomposition of oxygen molecules (O2) in a radio frequency discharge tube, and the produced O atomic beam was irradiated onto the target surfaces with different surface temperatures Ts. Time-of-flight distributions of O-atoms and O2 scattered from the surfaces were analyzed to obtain the initial sticking coefficient of O-atom S0, O. It is found that S0, O is monotonically decreased with an increase in Ts regardless of the surface materials employed. The values of S0, O on the quartz are 0.119–0.022 at Ts = 30–800 °C. On the other hand, S0, O on the SS are significantly higher than those on the quartz, and they are 0.503–0.135 at Ts = 30–800 °C. As for the alumina, S0, O at Ts = 30 °C is almost the same as that for the quartz, while S0, O becomes almost 0 at Ts ≧ 600 °C, showing much lower O affinity than the quartz.