Detailed Formation Mechanism Research Articles

Formation mechanism of soot in pyrolysis of 2-methylfuran under high temperature based on ReaxFF molecular dynamics simulation

In this study, the detailed mechanism of soot formation under high temperature pyrolysis of 2-methylfuran (2-MF) has been investigated by using Reactive force field molecular dynamics (ReaxFF MD) simulation. The MD analysis shows that 2-MF undergoes ring cleavage and the removal of CO/HCO/CH2CO/CH3CO, which results in the production of the C2-C4 species, promoting the formation of the initial ring molecules. The clustering of hydrocarbons by radical-chain reaction (CHRCR) mechanism plays a significant role in the mass growth of both polycyclic aromatic hydrocarbons (PAHs) and initial soot particles. The main contributors to this process are C2H2 and resonance-stabilized free radicals of C3 and C4. The H-abstraction-C2H2-addition (HACA) mechanism is important for the formation of surface active sites for PAHs and initial soot to some extent. In addition, the soot formation capacity of 2,5-dimethylfuran (25DMF) and 2-MF are compared. Under the same simulation conditions, 25DMF exhibits a higher capacity to form soot. Compared with 2-MF, 25DMF pyrolysis forms more ring-containing species at the initial stage, particularly cyclopentadiene and its derivatives. These compounds have the ability to promote the formation of PAHs, thus providing further support to the experimental-based theory.

(Invited) Single-Molecule Electroluminescence Triggered by Field-Driven Tunneling Electrons

Exciton dynamics governs versatile functions of molecules such as photon emission, photovoltaic and photo chemical reactions. For clarifying the dynamics of excitons in a molecule, an optical measurement with high spatiotemporal resolution is required because the excitons have short lifetimes and their behavior in the local region is important for optical properties. Luminescence spectroscopy based on a scanning tunneling microscope (STM) enable to investigate optical properties with sub-nanometer spatial resolution[1-2]. In this method, scanning tunneling luminescence (STL) spectroscopy, a molecule is excited by the tunneling current of an STM, which can be controlled with atomic spatial resolution. In contrast, the time resolution of STL spectroscopy is limited, because the tunnel current is controlled by electrical circuits. Therefore, this method cannot be used to track the picosecond dynamics of excitons. For overcoming the time-resolution of STL, we have combined a single-cycle terahertz (THz) pulse with STL spectroscopy. By coupling the THz pulse to a tip of an STM, the photoelectric field of THz pulse with sub picosecond time width is confined to the tip apex, which enables to manipulate the tunneling electrons with high spatiotemporal resolutions[4-9]. In this work, we succeeded in forming an exciton in a single molecule by using THz-field-driven current and clarifying the mechanism of the exciton formation.Single-cycle THz pulses were generated by using optical rectification of near infrared (NIR) laser pulses from a Yb fiber laser using a tilted-pulse-front configuration (Fig. 1a). The generated THz pulses were guided into the STM chamber and focused by using a lens near the tip. We prepared a clean Ag(111) surface and deposited NaCl films. Then, we deposited Pd phthalocyanine (PdPc) molecules on the NaCl/Ag(111) surface. Figure 1b shows THz-STL spectra of a PdPc on NaCl/Ag(111). Several sharp peaks appeared at around 1.9 eV in the red spectrum (with THz irradiation) and no peak appeared in the gray spectrum (without THz). The peak energy of the main peak is identical to the fluorescence peak of a PdPc measured by conventional STL[3], thus we concluded that the singlet excited state was formed by THz-field-driven tunneling. In this presentation, we would like to discuss the detailed mechanism for the exciton formation in a molecule by THz-field-driven electrons.[1] H. Imada et al., Nature 538, 364 (2016). [2] K. Kimura et al., Nature 570, 210 (2019). [3] S. Cao et al., Nat. Chem. 13, 766 (2021). [4] T. L. Cocker et al., Nat. Photon. 7, 620 (2013). [5] K. Yoshioka et al., Nat. Photon. 10, 762 (2016). [6] V. Jelic et al., Nature Physics 13, 591 (2017). [7] D. Peller et al., Nature 585, 58 (2020). [8] L. Wang 376, 401 (2022). [9] K. Kimura et al., ACS photon. 8, 982 (2021). Figure 1

Dynamic transition of internal oxides during high dew point heat treatment in Fe-2.4Mn-0.4Si-0.13C alloy

The origin of the dynamic transition of internal oxides was clarified in Fe‐2.4Mn‐0.4Si‐0.13C‐based steel during decarburization annealing at 1073 K. High dew point with H2 gas leads to the formation of deep decarburized ferrite layers containing grain boundary internal oxides. Microstructural characterization reveals the oxide transition from Mn2SiO4 to α-SiO2 at the tip of the internal oxidation layer and from α-SiO2 to Mn2SiO4 at the middle range of the internal oxidation layer. The dynamic transition between Mn2SiO4 and α-SiO2 is understood by the depletion in Mn contents and change of oxygen content, which change the normalized driving force of both oxides. The study gives a detailed mechanism of internal oxide formation and growth in multi-phase steel during high dew point annealing. Impact statementDuring high dew-point decarburization annealing, the fluctuation of Mn contents affects the driving force to form an internal oxide, resulting in the dynamic transition between Mn2SiO4 and α-SiO2.

Formation mechanism of environmentally persistent free radicals during soot aging

Environmentally persistent free radicals (EPFRs) are a newly emerging class of pollutants that are known to be formed on metal oxides (MOs). Recent experimental investigations have suggested that EPFRs may also be formed on soot. However, little is known about the structural and compositional characteristics of soot surfaces conducive to EPFRs formation. Concurrently, the changes in the surface structure and composition of soot indicate its aging process, yet the detailed mechanism underlying EPFRs formation in this process remain obscure. Additionally, it is uncertain whether the formation mechanism of EPFRs on soot differs from that on MOs. In this study, the density functional theory (DFT) and ab initio molecular dynamics (AIMD) were used to investigate EPFRs formation on soot at different stages of aging. The results indicate that EPFRs could be formed on both the complete soot surface with hydroxyl groups and the defective surface. Correspondingly, during the aging process of soot, the formation trend of EPFRs increases in the early stage of the aging process and then decreases over time. Additionally, the formation mechanism on soot is different from that on CuO. On soot, the EPFRs formation is initiated by free hydroxyl radical formed through the desorption process, following the Eley-Rideal mechanism, while on CuO surfaces, its formation involves the surface-bound hydroxyl groups, and thus follows the Langmuir-Hinshelwood mechanism. Furthermore, EPFRs triggered by soot are less stable than those by CuO, due to the easier desorption process of phenoxyl radicals on soot. These findings provide valuable insights into the detailed formation mechanism of EPFRs on soot at different stages of aging, thereby contributing to control EPFRs emissions from a mechanism perspective.

Formation of macroscopic black dots in transparent alumina ceramics prepared by pulsed electric current sintering

Transparent alumina ceramics produced by pulsed electric current sintering (PECS) include black dots, which can be observed with the naked eye. These black dots have porous structures caused by the aggregates in the raw powder. In order to investigate the detailed mechanism of black dot formation, transparent alumina ceramics were prepared by sintering α-alumina granules to produce large pseudo-aggregates and introducing them into α-alumina powder for PECS. Macroscopic black dots were formed in the sample. Characteristic Raman peaks of graphite were detected in porous parts of these macroscopic black dots. Analysis of gas phases generated from graphite sheets for PECS suspected to be involved in carbon contamination showed CO and CO2 generation. In thermodynamic calculations on carbon activity during PECS, gas phase including CO and CO2 generated from the hot graphite mold/sheet permeates the porous part of the cold sample, and the carbon activity of gases including CO and CO2 on the porous surface theoretically exceeds unity. Then, CO is adsorbed and decomposed on the porous surface, resulting in carbon contamination. The formation of macroscopic black dots is caused by carbon deposition in agglomerates of the raw powder from CO generated by graphite sheets during PECS.

Omegasomes control formation, expansion, and closure of autophagosomes.

Autophagy, an essential cellular process for maintaining cellular homeostasis and eliminating harmful cytoplasmic objects, involves the de novo formation of double-membraned autophagosomes that engulf and degrade cellular debris, protein aggregates, damaged organelles, and pathogens. Central to this process is the phagophore, which forms from donor membranes rich in lipids synthesized at various cellular sites, including the endoplasmic reticulum (ER), which has emerged as a primary source. The ER-associated omegasomes, characterized by their distinctive omega-shaped structure and accumulation of phosphatidylinositol 3-phosphate (PI3P), play a pivotal role in autophagosome formation. Omegasomes are thought to serve as platforms for phagophore assembly by recruiting essential proteins such as DFCP1/ZFYVE1 and facilitating lipid transfer to expand the phagophore. Despite the critical importance of phagophore biogenesis, many aspects remain poorly understood, particularly the complete range of proteins involved in omegasome dynamics, and the detailed mechanisms of lipid transfer and membrane contact site formation.

Reproduction of fissure corrosion and mechanism for fissure formation on ductile cast iron

On some cast iron pipes corroded under tensile stress, corrosion with a characteristic surface appearance, known as “fissure corrosion,” was occasionally observed. Because fissure corrosion on ductile cast iron pipes has been rarely studied, the detailed conditions and mechanism for fissure formation are still elusive. In this study, the levels of tensile stress and anodic current density causing fissure corrosion on ductile cast iron were investigated through laboratory experiments to reproduce fissure corrosion and elucidate its mechanism. Fissure corrosion was reproduced at bending tensile stresses ≥200 MPa. The depth difference between the peak and valley of fissures increased with increasing anodic current density, and the fissure corrosion was attributed to the difference between the anodic current densities of the peak and valley due to plastic deformation by stress concentration. Fissure corrosion was likely to be suppressed by reducing the anodic current flowing out of ductile cast iron surface.

Growth Process of Fe-O Nanoclusters with Different Sizes Biosynthesized by Protein Nanocages.

All protein-directed syntheses of metal nanoclusters (NCs) and nanoparticles (NPs) have attracted considerable attention because protein scaffolds provide a unique metal coordination environment and can adjust the shape and morphology of NCs and NPs. However, the detailed formation mechanisms of NCs or NPs directed by protein templates remain unclear. In this study, by taking advantage of the ferritin nanocage as a biotemplate to monitor the growth of Fe-O NCs as a function of time, we synthesized a series of iron NCs with different sizes and shapes and subsequently solved their corresponding three-dimensional atomic-scale structures by X-ray protein crystallography and cryo-electron microscopy. The time-dependent structure analyses revealed the growth process of these Fe-O NCs with the 4-fold channel of ferritin as nucleation sites. To our knowledge, the newly biosynthesized Fe35O23Glu12 represents the largest Fe-O NCs with a definite atomic structure. This study contributes to our understanding of the formation mechanism of iron NCs and provides an effective method for metal NC synthesis.

Insights into the pyrolytic coking process of RP-3 fuel from ReaxFF molecular dynamics

Active cooling technology serves as one of the promising and effective methods for addressing the thermal protection strategy for hypersonic aircraft. While the coke generated through pyrolysis, dehydrogenation and coking reactions of fuel will reduce the heat transfer efficiency, even clog the heat exchange channel. In this work, three-component RP-3 aviation fuel was adopted as model compounds to investigate the cracking coking reaction mechanism and explore the method of inhibiting coking. It is found that the three-component RP-3 molecules generate an intermediate system dominated by C2 products through bond breaking, reforming and bimolecular reactions (mainly hydrogen abstraction reactions) under supercritical state, in which the ·H radicals, as represented radicals, play a crucial role in the opening of benzene rings. The coking process is analyzed in details furtherly, and detailed soot formation mechanisms are revealed. Additionally, a suitable “core-shell structure” model is proposed to describe the coke formation process. Meanwhile, it is found that the addition of a small number of addition agents can effectively inhibit the formation of coke and thus prolong the residence time of fuel molecules in the heat transfer channel for the coking process mainly consisted of addition reaction. The study attempts to provide a theoretical basis for the high-temperature pyrolytic coking mechanism of endothermic hydrocarbon fuel, as well as the significance to understanding the inhibition of coke formation.

A Morphokinematic Study of the Enigmatic Emission Nebula NGC 6164/5 Surrounding the Magnetic O-type Star HD 148937

HD 148937 is a peculiar massive star (Of?p) with a strong magnetic field (1 kG). The hourglass-shaped emission nebula NGC 6164/5 surrounds this star. This nebula is presumed to originate from episodic mass-loss events of the central O-type star, but the detailed formation mechanism is not yet well understood. Grasping its three-dimensional structure is essential to uncovering the origin of this nebula. Here we report the high-resolution multiobject spectroscopic observations of NGC 6164/5 using the GIRAFFE on the 8.2 m Very Large Telescope. Integrated intensity maps constructed from several spectral lines delineate well the overall shape of this nebula, such as the two bright lobes and the inner gas region. The position–velocity diagrams show that the two bright lobes are found to be redshifted and blueshifted, respectively, while the inner region has multiple layers. We consider a geometric model composed of a bilateral outflow harboring nitrogen-enriched knots and expanding inner shells. Its spectral features are then simulated by using a Monte Carlo radiative transfer technique for different sets of velocities. Some position–velocity diagrams from simulations are very similar to the observed ones. According to the model that best reproduces the observational data, the two bright lobes and the nitrogen-enriched knots are moving away from HD 148937 at about 120 km s−1. Their minimum kinematic age is estimated to be about 7500 yr. We discuss possible formation mechanisms of this nebula in the context of binary interaction.

Re-entry in models of cardiac ventricular tissue with scar represented as a Gaussian random field.

Introduction: Fibrotic scar in the heart is known to act as a substrate for arrhythmias. Regions of fibrotic scar are associated with slowed or blocked conduction of the action potential, but the detailed mechanisms of arrhythmia formation are not well characterised and this can limit the effective diagnosis and treatment of scar in patients. The aim of this computational study was to evaluate different representations of fibrotic scar in models of 2D 10 10 cm ventricular tissue, where the region of scar was defined by sampling a Gaussian random field with an adjustable length scale of between 1.25 and 10.0 mm. Methods: Cellular electrophysiology was represented by the Ten Tusscher 2006 model for human ventricular cells. Fibrotic scar was represented as a spatially varying diffusion, with different models of the boundary between normal and fibrotic tissue. Dispersion of activation time and action potential duration (APD) dispersion was assessed in each sample by pacing at an S1 cycle length of 400 ms followed by a premature S2 beat with a coupling interval of 323 ms. Vulnerability to reentry was assessed with an aggressive pacing protocol. In all models, simulated fibrosis acted to delay activation, to increase the dispersion of APD, and to generate re-entry. Results: A higher incidence of re-entry was observed in models with simulated fibrotic scar at shorter length scale, but the type of model used to represent fibrotic scar had a much bigger influence on the incidence of reentry. Discussion: This study shows that in computational models of fibrotic scar the effects that lead to either block or propagation of the action potential are strongly influenced by the way that fibrotic scar is represented in the model, and so the results of computational studies involving fibrotic scar should be interpreted carefully.

A Gate-Tunable Ambipolar Quantum Phase Transition in a Topological Excitonic Insulator.

Coulomb interactions among electrons and holes in 2D semimetals with overlapping valence and conduction bands can give rise to a correlated insulating ground state via exciton formation and condensation. One candidate material in which such excitonic state uniquely combines with non-trivial band topology are atomic monolayers of tungsten ditelluride (WTe2 ), in which a 2D topological excitonic insulator (2D TEI) forms. However, the detailed mechanism of the 2D bulk gap formation in WTe2 , in particular with regard to the role of Coulomb interactions, has remained a subject of ongoing debate. Here, it shows that WTe2 is susceptible to a gate-tunable quantum phase transition, evident from an abrupt collapse of its 2D bulk energy gap upon ambipolar field-effect doping. Such gate tunability of a 2D TEI, into either n- and p-type semimetals, promises novel handles of control over non-trivial 2D superconductivity with excitonicpairing.

A VUV photoionization study on the gas-phase synthesis of the first five-membered carbon ring - C7H6 isomers

Utilizing synchrotron photoionization and molecular-beam mass spectrometry methodologies, this investigation deciphered the gas-phase reaction of propargyl with vinylacetylene by employing a high-temperature micro reactor within a time scale of tens to hundreds of microseconds, thereby precluding interference from secondary reactions. One of the typical C5-membered cyclic structures, fulvenallene, along with its isomers 1-ethynyl-1,3-cyclopentadiene and 5-ethynyl-1,3-cyclopentadiene, were synthesized. The latter two isomers were detected and identified for the first time within the confines of our experiments. The detailed formation mechanisms of these C7H6 isomers were meticulously examined with the incorporation of quantum computations on the potential energy surfaces and rate constants.

Formation of two-dimensional laser-induced periodic surface structures on titanium by GHz burst mode femtosecond laser pulses

GHz burst mode femtosecond (fs) laser pulses, which consist of a series of pulse trains with ultra-fast intervals of several hundred picoseconds, have offered distinct features for material processing compared to conventional irradiation of laser pulses (single-pulse mode). We apply GHz burst mode processing to fabricate laser-induced periodic surface structures (LIPSS) on the material surfaces. In our previous work for silicon (Si), we have found that GHz burst mode can create unique two-dimensional (2D) LIPSS composed of both parallel and perpendicular to the laser polarization direction. We proposed that the formation of 2D-LIPSS is attributed to the synergetic contributions of electromagnetic and hydrodynamic mechanisms. To further investigate more detailed formation mechanisms and explore practical applications, we employ titanium (Ti), whose properties are significantly different from Si. We demonstrate that GHz burst mode fs laser pulses (central wavelength: 1,030 nm, intra-pulse width: 230 fs, intra-pulse repetition rate (an intra-pulse interval): 4.88 GHz (205 ps) and burst pulse repetition rate: 10 kHz) can also fabricate 2D-LIPSS on Ti surfaces. We attribute the dominant formation mechanism of 2D-LIPSS to the generation of hot spots with highly enhanced electric fields due to transient change of material properties during GHz burst pulse irradiation. Based on this speculation, properly tailoring the shapes of the burst pulse with an optimum intra-pulse number enables the creation of well-defined 2D-LIPSS. Furthermore, essentially homogeneous 2D-LIPSS can be formed in a large area by laser scanning of a focused fs laser beam with a stage scanning speed of 5 mm/s.

Yellow pigments produced by oxidative oligomerization of dihydrochalcone glucoside and the reaction mechanism.

From the dried leaves of Lithocarpus polystachyus, yellow pigments, lithocarputins B (11) and C (12), were isolated with a colorless dihydrochalcone dimer, lithocarputin A (10). The pigments 11 and 12 are dimeric dihydrochalcone glycosides with bicyclo[3.2.1]octane structures. Each pigment is a diastereomeric mixture with enantiomeric aglycones that could not be separated. The production mechanisms of the pigments were proposed based on the in vitro enzymatic preparation from trilobatin (1), the major dihydrochalcone glucoside of L. polystachyus. The majority of the pigments in the dried leaves were the oligomers of the dihydrochalcone glycosides generated by a mechanism similar to dimerization. The pigments are probably artifacts produced in the drying process. This is the first report disclosing a detailed chemical mechanism for pigment formation from dihydrochalcone.

Electron energy levels determining cathode electrolyte interphase formation

AbstractCathode electrolyte interphase (CEI) has a significant impact on the performance of rechargeable batteries and is gaining increasing attention. Understanding the fundamental and detailed CEI formation mechanism is of critical importance for battery chemistry. Herein, a diverse of characterization tools are utilized to comprehensively analyze the composition of the CEI layer as well as its formation mechanism by LiCoO2 (LCO) cathode. We reveal that CEI is mainly composed of the reduction products of electrolyte and it only parasitizes the degraded LCO surface which has transformed into a disordered spinel structure due to oxygen loss and lithium depletion. Based on the energy diagram and the chemical potential analysis, the CEI formation process has been well explained, and the proposed CEI formation mechanism is further experimentally validated. This work highlights that the CEI formation process is nearly identical to that of the anode‐electrolyte‐interphase, both of which are generated due to the electrolyte directly in contact with the low chemical potential electrode material. This work can deepen and refresh our understanding of CEI.

Synthesis and Characterization of Hydrothermal Synthesized Ultra-Red CdS1−x Se x Pigment

Ultra-red pigment is in urgent need to enrich the colour range as well as to improve the quality of ceramic product. In this study, ultra-red CdS1−x Se x pigments (CP) were synthesized through hydrothermal technique. The effects of S/Se ratio on the structural and optical properties of CPs were investigated. CPs were characterized by XRD, ICP, SEM and UV-vis techniques. The colorimetric parameters of CPs were measured as also their band-gaps were estimated based on Tauc plot method. Furthermore, detailed formation mechanism of CdS1−x Se x has been elucidated. The results demonstrate that different compositions of CdS1−x Se x can be facilely obtained by adjusting the R value (starting S/Se molar ratio); when R is equal to 0.67 and 0.83, the prepared samples are CdS0.75Se0.25, when R is equal to 1.00, 1.17 and 1.33, the prepared samples are CdS0.571Se0.429. It is found that excessive S2− plays critical role in CdS1−x Se x formation. CP prepared with R=1.00 owns L*=44.69, a*=49.93, b*=22.66, implying an excellent red colour, which indicates potential use as an ultra-red ceramic pigment.

Initial Stage of Syringyl Lignin Formation from Sinapyl Alcohol.

Elucidating the detailed structure and formation mechanism of lignin, especially understudied syringyl (S) lignin, advances our knowledge of lignocellulosic biomass. To examine the early stages of S-lignin formation from sinapyl alcohol (SA), the FMR (flow microreactor) method and the Zutropf (gradual addition of SA) method with limited amounts of H2O2 were employed for the peroxidase-catalyzed dehydrogenative polymerization of SA. Only β-β dimers and not β-O-4 dimers were obtained as initial dimerization products. Six new oligoligognols up to pentamers with β-β and β-O-4 structures were identified. The erythro isomer was preferentially formed over the threo isomer in the β-O-4 structures, similar to that found in naturally occurring S-rich hardwood lignin. Although minor substructures, the α-oxidized β-β and β-O-4 structures and spirodienone (β-1) structure identified in this study demonstrate the characteristic features of S-rich lignin. Based on the identified products, the initial formation mechanism of S-lignin from SA was proposed.

Regulation of biofilm formation in Klebsiella pneumoniae.

Klebsiella pneumoniae is an important Gram-negative opportunistic pathogen that is responsible for a variety of nosocomial and community-acquired infections. Klebsiella pneumoniae has become a major public health issue owing to the rapid global spread of extensively-drug resistant (XDR) and hypervirulent strains. Biofilm formation is an important virulence trait of K. pneumoniae. A biofilm is an aggregate of microorganisms attached to an inert or living surface by a self-produced exo-polymeric matrix that includes proteins, polysaccharides and extracellular DNA. Bacteria within the biofilm are shielded from antibiotics treatments and host immune responses, making it more difficult to eradicate K. pneumoniae-induced infection. However, the detailed mechanisms of biofilm formation in K. pneumoniae are still not clear. Here, we review the factors involved in the biofilm formation of K. pneumoniae, which might provide new clues to address this clinical challenge.

Measuring and modeling investigation of the net photochemical ozone production rate via an improved dual-channel reaction chamber technique

Abstract. Current process-based research mainly uses box models to evaluate photochemical ozone production and destruction rates, and it is unclear to what extent the photochemical reaction mechanisms are elucidated. Here, we modified and improved a net photochemical ozone production rate (NPOPR, P(O3)net) detection system based on the current dual-channel reaction chamber technique, which makes the instrument applicable to different ambient environments, and its various operating indicators were characterized, i.e., “airtightness”, light transmittance, wall losses of the reaction and reference chambers, conversion rate of O3 to NO2, air residence time, and performance of the reaction and reference chambers. The limits of detection of the NPOPR detection system were determined to be 0.07, 1.4, and 2.3 ppbv h−1 at sampling flow rates of 1.3, 3, and 5 L min−1, respectively. We further applied the NPOPR detection system to field observations at an urban site in the Pearl River Delta (China). During the observation period, the maximum value of P(O3)net was 34.1 ppbv h−1, which was ∼ 0 ppbv h−1 at night within the system detection error and peaked at approximately noon local time. The daytime (from 06:00–18:00 LT) average value of P(O3)net was 12.8 (± 5.5) ppbv h−1. We investigated the detailed photochemical O3 formation mechanism in the reaction and reference chambers of the NPOPR detection system using a zero-dimensional box model. We found that the photochemical reactions in the reaction chamber were very close to those in ambient air, but there was not zero chemistry in the reference chamber because the reaction related to the production and destruction of RO2 (= HO2 + RO2) continued in the reference chamber, which led to a small amount of P(O3)net. Therefore, the P(O3)net measured here can be regarded as the lower limit of the real P(O3)net in the atmosphere; however, the measured P(O3)net was still ∼ 7.5 to 9.3 ppbv h−1 higher than the modeled P(O3)net value depending on different modeling methods, which may be due to the inaccurate estimation of HO2 / RO2 radicals in the modeling study. Short-lived intermediate measurements coupled with direct P(O3)net measurements are needed in the future to better understand O3 photochemistry. Our results show that the NPOPR detection system can achieve high temporal resolution and continuous field observations, which helps us to better understand photochemical O3 formation and provides a key scientific basis for continuous improvement of air quality in China.