RESUMO
Rationally tuning the emission position and narrowing the full width at half-maximum (FWHM) of an emitter is of great importance for many applications. By synergistically improving rigidity, strengthening the resonant strength, inhibiting molecular bending and rocking, and destabilizing the HOMO energy level, a deep-blue emitter (CZ2CO) with a peak wavelength of 440â nm and an ultranarrow spectral FWHM of 16â nm (0.10â eV) was developed via intramolecular cyclization in a carbonyl/N resonant core (QAO). The dominant υ0-0 transition character of CZ2CO gives a Commission Internationale de I'Éclairage coordinates (CIE) of (0.144, 0.042), nicely complying with the BT.2020 standard. Moreover, a hyper-fluorescent device based on CZ2CO shows a high maximum external quantum efficiency (EQEmax ) of 25.6 % and maintains an EQE of 22.4 % at a practical brightness of 1000â cd m-2 .
RESUMO
The development of photoinduced luminescent radicals with dynamic emission color is still challenging. Herein we report a novel molecular radical system (TBIQ) that shows photo-controllable luminescence, leading to a wide range of ratiometric color changes via light excitation. The conjugated skeleton of TBIQ is decorated with steric-demanding tertiary butyl groups that enable appropriate intermolecular interaction to make dynamic intermolecular coupling possible for controllable behaviors. We reveal that the helicenic pseudo-planar conformation of TBIQ experiences a planarization process after light excitation, leading to more compactly stacked supermolecules and thus generating radicals via intermolecular charge transfer. The photo-controllable luminescent radical system is employed for a high-level information encryption application. This study may offer unique insight into molecular dynamic motion for optical manufacturing and broaden the scope of smart-responsive materials for advanced applications.
RESUMO
Upon fusing the pyrazinyl pyrazole entity in giving pyrazolo[3,4-f]quinoxaline chelate, the corresponding Os(II) based NIR emitter exhibited "invisible" and efficient electroluminescence with a peak maximum at 811â nm. A maximum external quantum efficiency of 0.97 % and a suppressed efficiency roll-off till a current density of 300â mA cm-2 was also exhibited.
RESUMO
Multi-resonance thermally activated delayed fluorophores have been actively studied for high-resolution photonic applications due to their exceptional color purity. However, these compounds encounter challenges associated with the inefficient spin-flip process, compromising device performance. Herein, we report two pure-blue emitters based on an organoboron multi-resonance core, incorporating a conformationally flexible donor, 10-phenyl-5H-phenophosphazinine 10-oxide (or sulfide). This design concept selectively modifies the orbital type of high-lying excited states to a charge transfer configuration while simultaneously providing the necessary conformational freedom to enhance the density of excited states without sacrificing color purity. We show that the different embedded phosphorus motifs (phosphine oxide/sulfide) of the donor can finely tune the electronic structure and conformational freedom, resulting in an accelerated spin-flip process through intense spin-vibronic coupling, achieving over a 20-fold increase in the reverse intersystem crossing rate compared to the parent multi-resonance emitter. Utilizing these emitters, we achieve high-performance pure-blue organic light-emitting diodes, showcasing a top-tier external quantum efficiency of 37.6% with reduced efficiency roll-offs. This proposed strategy not only challenges the conventional notion that flexible electron-donors are undesirable for constructing narrowband emitters but also offer a pathway for designing efficient narrow-spectrum blue organic light-emitting diodes.
RESUMO
Molecular fluorophores with the second near-infrared (NIR-II) emission hold great potential for deep-tissue bioimaging owing to their excellent biocompatibility and high resolution. Recently, J-aggregates are used to construct long-wavelength NIR-II emitters as their optical bands show remarkable red shifts upon forming water-dispersible nano-aggregates. However, their wide applications in the NIR-II fluorescence imaging are impeded by the limited varieties of J-type backbone and serious fluorescence quenching. Herein, a bright benzo[c]thiophene (BT) J-aggregate fluorophore (BT6) with anti-quenching effect is reported for highly efficient NIR-II bioimaging and phototheranostics. The BT fluorophores are manipulated to have Stokes shift over 400 nm and aggregation-induced emission (AIE) property for conquering the self-quenching issue of the J-type fluorophores. Upon forming BT6 assemblies in an aqueous environment, the absorption over 800 nm and NIR-II emission over 1000 nm are boosted for more than 41 and 26 folds, respectively. In vivo visualization of the whole-body blood vessel and imaging-guided phototherapy results verify that BT6 NPs are excellent agent for NIR-II fluorescence imaging and cancer phototheranostics. This work develops a strategy to construct bright NIR-II J-aggregates with precisely manipulated anti-quenching properties for highly efficient biomedical applications.
Assuntos
Nanopartículas , Neoplasias , Humanos , Corantes Fluorescentes/farmacologia , Fototerapia , Imagem Óptica/métodosRESUMO
Simultaneously realizing improved carrier mobility and good photoluminescence (PL) efficiency in red thermally activated delayed-fluorescence (TADF) emitters remains challenging but important. Herein, two isomeric orange-red TADF emitters, oPDM and pPDM, with the same basic donor-acceptor backbone but a pyrimidine (Pm) attachment at different positions are designed and synthesized. The two emitters show similarly good PL properties, including narrow singlet-triplet energy offsets (0.11 and 0.15 eV) and high photoluminescence quantum yields (ca. 100 and 88%) in doped films. An orange-red organic light-emitting diode (OLED) employing oPDM as an emitter achieves an almost twice as high maximum external quantum efficiency (28.2%) compared with that of a pPDM-based OLED. More balanced carrier-transporting properties are responsible for their contrasting device performances, and the position effect of the Pm substituent leads to significantly distinct molecular packing behaviors in the aggregate states and different carrier mobilities.
RESUMO
To achieve high-efficiency deep-blue electroluminescence satisfying Rec.2020 standard blue gamut, two thermally activated delayed fluorescent (TADF) emitters are developed: 5-(2,12-di-tert-butyl-5,9-dioxa-13b-boranaphtho[3,2,1-de]anthracen-7-yl)-10,10-diphenyl-5,10-dihydrodibenzo[b,e][1,4]azasiline (TDBA-PAS) and 10-(2,12-di-tert-butyl-5,9-dioxa-13b-boranaphtho[3,2,1-de]anthracen-7-yl)-9,9-diphenyl-9,10-dihydroacridine (TDBA-DPAC). Inheriting from their parented organoboron multi-resonance core, both emitters show very promising deep-blue emissions with relatively narrow full width at half-maximum (FWHM, ≈50 nm in solution), high photoluminescence quantum yield (up to 92.3%), and short emission lifetime (≤2.49 µs) with fast reverse intersystem crossing (>106 s-1 ) in doped films. More importantly, replacing the spiro-centered sp3 C atom (TDBA-DPAC) with the larger-radius sp3 Si atom (TDBA-PAS), enhanced conformational heterogeneities in bulky-group-shielded TADF molecules are observed in solution, doped film, and device. Consequently, OLEDs based on TDBA-PAS retain high maximum external quantum efficiencies ≈20% with suppressed efficiency roll-off and color index close to Rec.2020 blue gamut over a wide doping range of 10-50 wt%. This study highlights a new strategy to restrain spectral broadening and redshifting and efficiency roll-off in the design of deep-blue TADF emitters.
RESUMO
An intercomparison of organic carbon (OC) and elemental carbon (EC) measurements was conducted based on ambient aerosol samples collected during four seasons in Beijing, China. Dependence of OC and EC values on the temperature protocol and the charring correction method is presented and influences of aerosol composition are investigated. EC was found to decrease with the peak inert mode temperature (T(peak)) such that EC determined by the IMPROVE (the Interagency Monitoring of Protected Visual Environments)-A protocol (T(peak) was 580 °C) was 2.85 ± 1.31 and 3.83 ± 2.58 times that measured by an alternative protocol with a T(peak) of 850 °C when using the transmittance and reflectance correction, respectively. It was also found that reflectance correction tends to classify more carbon as EC compared with transmittance; results from the IMPROVE-A protocol showed that the ratio of EC defined by reflectance correction (EC(R)) to that based on transmittance (EC(T)) averaged 1.50 ± 0.42. Moreover, it was demonstrated that emissions from biomass burning would increase the discrepancy between EC values determined by different temperature protocols. On the other hand, the discrepancy between EC(R) and EC(T) was strongly associated with secondary organic aerosol (SOA) which was shown to be an important source of the organics that pyrolyze during the inert mode of thermal-optical analysis.
Assuntos
Aerossóis/análise , Carbono/análise , Compostos Orgânicos/análise , China , Monitoramento AmbientalRESUMO
Enhancing the reverse intersystem crossing (RISC) process of thermally activated delayed fluorescent (TADF) emitters is an effective approach to realize efficient organic light-emitting diodes (OLEDs) with low efficiency roll-off. In this work, we designed two novel TADF emitters, SAT-DAC and SATX-DAC, via a spiro architecture. Efficient maximum external quantum efficiencies (EQEs) of 22.6 and 20.9% with reduced efficiency roll-off (EQEs of 17.9 and 17.0% at 1000 cd m-2) were achieved via a "two-RISC-channel" strategy. X-ray diffraction shows close donor (D)/acceptor (A) spacing and suitable D/A orientation in crystals of the two emitters favoring both intra- and intermolecular through-space charge transfer (TSCT) processes. Transient photoluminescence decay measurements show that both emitters have two RISC channels leading to kISCT exceeding 106 s-1. These results suggest that the "two-RISC-channel" design can be a novel approach for enhancing performance of TADF emitters, in particular at high excitation densities.
RESUMO
This study assesses the chemical characteristics of As in aerosol PM2.5 samples that were collected from July 2011 to May 2012 in Beijing, China. Total As, As(â ¢), and As(â ¤) were analyzed by inductively coupled plasma mass spectrometry (ICP-MS), high performance liquid chromatography (HPLC), and hydride generation atomic fluorescence (HG-AFS), respectively. The average concentrations of total As, As(â ¢) and As(â ¤) over the entire sampling period were (21.82±17.01), (3.15±1.94), and (10.78±5.39) ng·m-3, respectively. The average concentrations of total As, As(â ¢) and As(â ¤) were (16.62±5.80), (18.34±9.00), (21.49±10.22), and (29.52±27.97) ng·m-3 during the spring, (5.42±2.5), (1.61±0.51), (2.88±1.12), and (3.27±1.23) ng·m-3 during the summer, and (7.55±1.47), (13.57±13.34), (12.75±6.54), and (8.68±3.57) ng·m-3 during the winter, respectively. The average concentrations of As(â ¢) in different seasons were higher than As(â ¤) concentrations. Seasonal characteristics may be caused by seasonal differences in diffusion conditions, emission sources, and atmospheric oxidation. The ratios of average concentrations of As(â ¢)/As(â ¤) were 0.67 in spring, 0.13 in summer, 0.27 in autumn, and 0.44 in winter. Ratios of As(â ¢)/As(â ¤) were negatively correlated with relative humidity, which indicates that high humidity conditions may not have been favorable for the transformation of As(â ¢) into As(â ¤). As(â ¢)/As(â ¤) and As(â ¢) both showed positive correlations with Ca2+, thereby indicating that soil dust may have been an important source of As(â ¢).
RESUMO
Samples of particulate matter from coal-fired boilers of different tons were collected in Lanzhou city, and the water-soluble inorganic ions, carbonaceous species, water-soluble organic compounds (WSOC) and polycyclic aromatic hydrocarbons (PAHs) were analyzed. The results showed that SO42-, Cl-, and Ca2+ were the most important water-soluble ions in the coal-fired boiler samples, accounting for 35.13%, 23.16%, and 22.20% of the total mass of water-soluble ions, respectively. The pyrolysis composition spectra of the carbonaceous species were similar among the coal-fired boilers, and organic carbon fraction (OC1, OC2, OC3, and OC4),and elemental carbon fraction (EC1, EC2, and EC3) accounted for 1.04%, 8.26%, 20.09%, 6.78%, 51.08%, 7.09%, and 5.66% of the total carbon (TC), respectively. EC1 had the highest content and was the most important carbonaceous species. The average ratios of WSOC/TC and WSOC/OC were 0.09±0.07 and 0.23±0.12, respectively, and the difference among the boilers of different tons was large. Phenanthrene (Phe), pyrene (Pyr), and benzene(k)anthracene (BkF) were the three main components of the PAHs, accounting for 16.69%, 11.93%, and 10.66% of the total PAHs, respectively. The particulate water-soluble ions, organic/elemental carbon aerosol (OCEC) and WSOC emitted from different tons coal-fired boilers were not significantly linearly related to the tonnage of the steam boiler, and low molecular weight PAHs decreased with the increase of tonnage of the steam boiler.
RESUMO
A recent breakthrough in the discovery of thermally activated delayed fluorescence (TADF) emitters characterized by small single-triplet energy offsets (ΔEST) offers a wealth of new opportunities to exploit high-performance metal-free photosensitizers. In this report, two intrinsically cancer-mitochondria-targeted TADF emitters-based nanoparticles (TADF NPs) have been developed for two-photon-activated photodynamic therapy (PDT) and fluorescence imaging. The as-prepared TADF NPs integrate the merits of (1) high 1O2 quantum yield of 52%, (2) sufficient near-infrared light penetration depth due to two-photon activation, and (3) excellent structure-inherent mitochondria-targeting capabilities without extra chemical or physical modifications, inducing remarkable endogenous mitochondria-specific reactive oxygen species production and excellent cancer-cell-killing ability at an ultralow light irradiance. We believe that the development of such intrinsically multifunctional TADF NPs stemming from a single molecule will provide new insights into exploration of novel PDT agents with strong photosensitizing ability for various biomedical applications.
Assuntos
Corantes Fluorescentes/química , Mitocôndrias/patologia , Nanopartículas/química , Apoptose/efeitos dos fármacos , Apoptose/efeitos da radiação , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Sobrevivência Celular/efeitos da radiação , Humanos , Raios Infravermelhos , Microscopia Confocal , Microscopia de Fluorescência por Excitação Multifotônica , Mitocôndrias/efeitos dos fármacos , Nanopartículas/toxicidade , Neoplasias/tratamento farmacológico , Neoplasias/metabolismo , Neoplasias/patologia , Fotoquimioterapia , Fótons , Fármacos Fotossensibilizantes/química , Fármacos Fotossensibilizantes/farmacologia , Teoria Quântica , Oxigênio Singlete/metabolismoRESUMO
Simultaneous collections of non-methane hydrocarbons (NMHCs) were carried out at 15 sampling sites including urban, suburb and potential pollution areas in Cangzhou City in spring 2015. The results showed that NMHCs were generally higher in urban areas than those in suburb and rural areas; the highest concentration of NMHCs was observed at Cangzhou High-tech zone (urban area); the concentrations of NMHCs were significantly lower at rural sites than in most urban sites except Hejian site; vehicular emissions were the main sources of NMHCs in Cangzhou; Cangzhou chemical fertilizer plant and Cangzhou oil refinery had no significant influence on urban NMHCs during their shutdown period; Dagang Oilfield, with better oil and gas recovery systems, did not have a significant impact on urban NMHCs. In general, alkanes, alkenes and aromatics accounted for 65%, 16% and 19% of NMHCs in Cangzhou City, respectively; xylene (19%), ethylene (14%), toluene(11%), propylene (5%), isopentane (5%) and isopentene (5%) were the most dominant contributors to ozone formation potential; aerosol formation potential was mainly derived from toluene (28%), pinene (28%), xylene(16%), ethylbenzene (9%) and benzene (9%).
RESUMO
In order to investigate the chemical characteristics and sources of atmospheric heavy metals, PM2.5 samples were collected every three days during the summer of 2011 and summer of 2012. The samples were analyzed for Li, V, Cr, Mn, Co, Cu, Zn, As, Se, Ti, Ga, Ni, Sr, Cd, In, Ba, Tl, Pb, Bi, and U by ICP-MS, with an emphasis on seven major heavy metal elements (Zn, Pb, Mn, Cu, As, V, and Cr). The concentrations of Zn, Pb, Mn, Cu, As, V, and Cr were (331.30±254.52), (212.64±182.06), (85.96±47.00), (45.19±27.74), (17.13±19.02), (4.92±3.38), and (9.04±7.84) ng·m-3 in PM2.5 in Beijing during the summer of 2011 and the summer of 2012. In the autumn and winter seasons, PM2.5/heavy metal pollution is more severe than in spring and summer, which may be related to the increase in coal combustion used for heating in autumn and winter in Beijing. Haze pollution enhances the concentrations of seven heavy metals in PM2.5 in Beijing and the enhancement shows seasonal variations. The source analysis suggested that dust (including building dust and road dust) and coal combustion might be two most important sources of heavy metals in Beijing, and transport and other industrial sources cannot be ignored.
RESUMO
Pollution characteristic and variation trend of atmospheric carbonyls were investigated in November during the 2014 Beijing APEC. Formaldehyde, acetaldehyde and acetone were the dominant carbonyls, accounting for 82.66% of total carbonyls, and especially, formaldehyde accounted for 40.12% of total carbonyls. Atmospheric concentrations of total carbonyls decreased by around 64.10% after the clean air policy was carried out during the Beijing APEC, and the variation trend of carbonyls showed a similar pattern to those of other pollutants like PM2.5 during the APEC. Strong correlations (R² of 0.67-0.98) were observed among formaldehyde, acetaldehyde, acetone and total carbonyls during and after the APEC, indicating that they had similar sources; however, poor correlations (R² of -0.11-0.42 and 0.16-0.94, respectively) were observed before the APEC, implying different emission sources for ambient carbonyls. The calculated ratios of C1/C2, C2/C3 and OC/EC indicated that both vehicles and coal emissions were responsible for atmospheric carbonyls before the APEC, and emissions from coal burning were the major contributor to atmospheric carbonyls during and after the APEC, especially after the APEC.
Assuntos
Acetaldeído/análise , Acetona/análise , Poluentes Atmosféricos/análise , Monitoramento Ambiental , Formaldeído/análise , Pequim , Carvão Mineral , Tamanho da Partícula , Material Particulado/análiseRESUMO
In order to investigate the influence of the emission reduction measure during the Beijing APEC on the concentrations and pollution characteristics of humic-like substances (HULIS) in atmospheric fine particles, PM2.5 samples were collected and analyzed for OCEC, WSOC, HULIS and water-soluble ions. The concentration of HULIS in PM2.5 ranged 1 µg · m⻳-15 µg · m⻳. HULIS concentrations were 7.99 µg · m⻳, 5.83 µg · m⻳ and 7.06 µg · m⻳ before, during and after APEC, which indicated emission reduction measure had important effect on the reduction of HULlS. The decrease of HULIS during the APEC was significantly faster than those of EC and WSOC, while the increase of HULIS turned out to be much slower than OC, EC, WSOC and PM2.5 after the meeting. The proportions of HULIS to PM2.5 were 13.60%, 13.59%, 14.02% and 12.22% at four different stages, i. e., whole sampling period, before, during and after the APEC, while HULIS-C/OC and HULIS-C/WSOC were 28.95%, 35.51%, 28.37%, 19.93%; and 52.75%, 59.58%, 51.54%, 45.39%, respectively. HULlS was significantly positively correlated with humidity, while significantly negatively correlated with wind speed. Biomass burning and secondary transformation of VOCs might be two important sources of HULlS in Beijing.
Assuntos
Poluentes Atmosféricos/análise , Monitoramento Ambiental , Substâncias Húmicas/análise , Material Particulado/análise , Pequim , Tamanho da PartículaRESUMO
Polycyclic aromatic hydrocarbons (PAHs) are a group of important toxic compounds. In order to detect the pollutional characteristics of atmospheric PAHs in Fine Particulate Matter (PM2.5), a total of 60 PM2.5 samples were collected in Lanzhou City during the winter of 2012 and summer of 2013. The GC/MS measurement results of the samples demonstrated the averagely total mass concentrations of the most significant 16 homologues of PAHs were (191.79±88.29) ng·m-3 and (8.94±4.34) ng·m-3 in winter and summer respectively, indicating a higher pollution level in winter. In winter, the snowfall was the most important meteorological factor for the decrease of PAHs mass concentration in PM2.5. The percentages of PAHs with 4 rings were the highest in both winter (51.40%) and summer (49.94%) in Lanzhou. The percentage of PAHs with 5-6 rings in summer (41.04%) was higher than that in winter (24.94%). However, the percentage of PAHs with 2-3 rings in summer (9.03%) was lower than that in winter (23.67%). Based on the analysis of characteristic ratios, we concluded that the PAHs in atmospheric PM2.5 in Lanzhou were mainly sourced from coal and vehicle emissions in winter, especially the diesel vehicles. The absolute contributions of all possible PAHs pollution sources were insignificant in summer, with relatively higher contribution from gasoline vehicles.
RESUMO
Thirty non-methane hydrocarbons(NMHCs) samples were collected and analyzed in Foshan City during winter 2014 and summer 2015. The concentrations of NMHCs during the sampling period were 122.30 µg·m-3 and 56.22 µg·m-3 in winter and summer, respectively. The five highest concentration species of NMHCs in winter and summer were in the following order: toluene (25.12 µg·m-3), m/p-xylene (13.76 µg·m-3), propane (9.17 µg·m-3), ethylbenzene (7.25 µg·m-3), ethylene (6.77 µg·m-3) and toluene (6.18 µg·m-3), m/p-xylene (5.21 µg·m-3), o-xylene (4.15 µg·m-3), ß-pinene(3.75 µg·m-3), propane (3.29 µg·m-3). Compared to 2008, the concentrations of NMHCs have dropped significantly. The proportions of aromatics, alkanes, alkenes and alkynes in NMHCs were 51.20%, 34.70%, 10.04%, 4.05% and 43.93%, 33.99%, 19.20%, 2.88% during winter and summer, respectively. The ratios of NMHCs/NOx were 0.90 and 1.88, indicating that the peak ozone concentrations in Foshan City were controlled by NMHCs during the sampling period, and the emissions of NMHCs should be further strengthened. The propylene equivalent concentration and ozone formation potential were 45.09 µg·m-3 and 40.64 µg·m-3, 392.77 µg·m-3 and 207.77 µg·m-3 in winter and summer. The m/p-xylene; toluene and m/p-xylene; isoprene had a very important influence on ozone formation potential. The ratios of Benzene/Toluene were 0.15 and 0.20 indicated that industrial process was the main source of NMHCs in Foshan City. Relative to 2008, isopentane didn't belong to the highest concentration of five pollutants for Foshan's NMHCs in this research, indicating the measures to prevent volatile gasoline impact on the environmental quality have achieved remarkable results.
RESUMO
Foshan is a ceramics manufacturing center in the world and the most polluted city in the Pearl River Delta (PRD) in southern China measured by the levels of atmospheric heavy metals. PM2.5 samples were collected in Foshan in winter 2008. Among the 22 elements and ions analyzed, 7 heavy metals (Zn, V, Mn, Cu, As, Cd and Pb) were studied in depth for their levels, spatiotemporal variations and sources. The ambient concentrations of the heavy metals were much higher than the reported average concentrations in China. The levels of Pb (675.7 ± 378.5 ng/m(3)), As (76.6 ± 49.1 ng/m(3)) and Cd (42.6 ± 45.2 ng/m(3)) exceeded the reference values of NAAQS (GB3095-2012) and the health guidelines of the World Health Organization. Generally, the levels of atmospheric heavy metals showed spatial distribution as: downtown site (CC, Chancheng District)>urban sites (NH and SD, Nanhai and Shunde Districts)>rural site (SS, Shanshui District). Two sources of heavy metals, the ceramic and aluminum industries, were identified during the sampling period. The large number of ceramic manufactures was responsible for the high levels of atmospheric Zn, Pb and As in Chancheng District. Transport from an aluminum industry park under light north-west winds contributed high levels of Cd to the SS site (Shanshui District). The average concentration of Cd under north-west wind was 220 ng/m(3), 20.5 times higher than those under other wind directions. The high daily maximum enrichment factors (EFs) of Cd, Pb, Zn, As and Cu at all four sites indicated extremely high contamination by local emissions. Back trajectory analysis showed that the heavy metals were also closely associated with the pathway of air mass. A positive matrix factorization (PMF) method was applied to determine the source apportionment of these heavy metals. Five factors (industry including the ceramic industry and coal combustion, vehicle emissions, dust, transportation and sea salt) were identified and industry was the most important source of atmospheric heavy metals. The present paper suggests a control policy on the four heavy metals Cd, Pb, Zn, and Cu, and suggests the inclusion of As in the ceramic industry emission standard in the future.
Assuntos
Poluentes Atmosféricos/análise , Atmosfera/química , Monitoramento Ambiental , Metais Pesados/análise , China , Cidades , Material Particulado/análiseRESUMO
Benzene, toluene, ethylbenzene and dimethylbenzene are typical anthropogenic emitted organics in the atmosphere, which not only endanger human health but also actively participate in photochemical reactions, generating O3 and secondary organic aerosols. In order to investigate the pollution level and its ozone formation potentials, concentrations of BTEX and O3 were parallel measured by the passive sampler and analyzed using GC-MS and ICS-90 during 2008-2010 in urban Beijing. The results show that toluene was the most abundant compound (8.7 +/- 3.1) microg x m(-3), followed by benzene, ethylbenzene and m/p-xylene, with concentrations of (7.1 +/- 3.3), (4.2 +/- 1.4) and (3.4 +/- 1.5) microg x m(-3), respectively. Concentrations of BTEX peaked in winter, followed by autumn, summer, and spring, with values of (26.8 +/- 12.1), (25.9 +/- 4.9), (24.7 +/- 2.8) and (16.8 +/- 1.4) microg x m(-3), respectively. Benzene concentrations were the highest in winter, while for toluene, the concentration was higher in summer than that in winter. Based on the maximum incremental reactivity scale, m/p-xylene was found to be the dominant contributor to ozone formation among BTEX. The ozone formation potentials of BTEX in Beijing were 65.2, 60.2, and 75.7 microg x m(-3) in 2008, 2009, and 2010, respectively, which were consistent with the measured values of 80.5, 65.0, and 101.9 microg x m(-3) during the corresponding period. Vehicular emission and solvent evaporation were the major sources of BTEX. Concentrations of benzene were affected by coal heating in winter, whereas BTEX concentration was more influenced by solvent evaporation in summer, which had an important contribution to the formation of O3 in urban Beijing.