The influence effect of different holes per inch on the plasma parameters and particle growth has been studied by compression between two different gap Aluminum meshes of 3 mm width, and 8 holes per inch (8 h/in) and ...The influence effect of different holes per inch on the plasma parameters and particle growth has been studied by compression between two different gap Aluminum meshes of 3 mm width, and 8 holes per inch (8 h/in) and 0.3 mm width and 20 holes per inch (20 h/in) at very low pressure. The perforated aluminum mesh with small diameter holes 20 h/in shows a better glow discharge stabilization than mesh with large diameter holes 8 h/in. For both 20 h/in and 8 h/in, sharp axial decrements for electron Temperature (Te), where Te decreased from 5.2 to 3.8 eV for 8 h/in, from 2.75 to 1.8 eV for 20 h/in. In contrast sharp axial increments for electron density (Ne), whereas Ne increased from 0.9 × 109 to 20 × 109 cm-3 for 8 h/in and from 8 × 109 to 42 × 109 cm-3 for 20 h/in. Silicon wafer [100] was exposed directly behind the meshes to realize nano-particle growth in sputtering discharge, where there are two different particles shapes: spherical shape particles produced by 20 h/in, and filamentary-shaped fractal particles formed by 8 h/in. The particle radius growth for 20 h/in was in the range of 4.67 - 301 nm during exposure time 40 - 95 min, and for 8 h/in were in the range of 9.2 - 28.8 nm during exposure time 60 - 95 min.展开更多
Anatase nanoparticles modified by sulfate groups were synthesized using hydrothermal method. The particles were controlled to large sizes by simply adjusting the amount of H2O2, in which HOO^- ions replaced the surfac...Anatase nanoparticles modified by sulfate groups were synthesized using hydrothermal method. The particles were controlled to large sizes by simply adjusting the amount of H2O2, in which HOO^- ions replaced the surface sulfate groups and reduced the steric effect to promote the grain growth. The size-induced microstructural changes of the as-prepared nanoparticles were characterized using powder XRD, FT-IR, TG. and UV-vis analyses. The sulfate groups existed on anatase surface in unidentate and bidentate coordination forms. With the particle size reduction, bandgap energies of the as-prepared anatase nanoparticles decreased, and the desorption temperature of sulfate groups shifted towards lower temperatures.展开更多
研究气液交叉流阵列内传热传质自增湿形成过饱和条件下水蒸汽在PM 2.5 颗粒表面经历异质核化凝结长大的机理,并建立颗粒长大计算模型,逐排计算,确定颗粒粒径变化量。模型分析与计算结果解释了自增湿由强到弱的阵列条件下,实验检测到的PM...研究气液交叉流阵列内传热传质自增湿形成过饱和条件下水蒸汽在PM 2.5 颗粒表面经历异质核化凝结长大的机理,并建立颗粒长大计算模型,逐排计算,确定颗粒粒径变化量。模型分析与计算结果解释了自增湿由强到弱的阵列条件下,实验检测到的PM 2.5 颗粒粒径增长速度先增大后减小的规律。在气体温度T in =41.2℃,饱和度S R =0.85,横掠温度T w =5℃的一个单元(100排)降膜交叉阵列实验条件下,最大可达5.5μm/s的增长速度,且模型预测颗粒长大后粒径分布与实验结果吻合较好。展开更多
Particle number size distribution from 10 to 10,000 nm was measured by a wide-range particle spectrometer （WPS-1000XP） at a downwind site north of downtown Lanzhou, western China, from 25 june to 19 July 2006. We fi...Particle number size distribution from 10 to 10,000 nm was measured by a wide-range particle spectrometer （WPS-1000XP） at a downwind site north of downtown Lanzhou, western China, from 25 june to 19 July 2006. We first report the pollution level, diurnal variation of particle concentration in different size ranges and then introduce the characteristics of the particle formation processes, to show that the number concentration of ultrafine particles was lower than the values measured in other urban or suburban areas in previous studies, However, the fraction of ultrafine particles in total aerosol number concentration was found to be much higher. Furthermore, sharp increase of ultrafine particle concentration was frequently observed at noon. An examination of the diurnal pattern suggests that the burst of the ultrafine particles was mainly due to nucleation process. During the 25-day observation, new particle formation （NPF） from homogeneous nucleation was observed during 33% of the study period. The average growth rate of the newly formed particles was 4.4 nm/h, varying from 1.3 to 16,9 nm/h. The needed concentration of condensable vapor was 6.1 × 10^7 cm-3, and its source rate was 1.1× 10^6 cm-3 s 1. Further calculation on the source rate of sulphuric acid vapor indicated that the average participation of sulphuric acid to particle growth rate was 68.3%.展开更多
文摘The influence effect of different holes per inch on the plasma parameters and particle growth has been studied by compression between two different gap Aluminum meshes of 3 mm width, and 8 holes per inch (8 h/in) and 0.3 mm width and 20 holes per inch (20 h/in) at very low pressure. The perforated aluminum mesh with small diameter holes 20 h/in shows a better glow discharge stabilization than mesh with large diameter holes 8 h/in. For both 20 h/in and 8 h/in, sharp axial decrements for electron Temperature (Te), where Te decreased from 5.2 to 3.8 eV for 8 h/in, from 2.75 to 1.8 eV for 20 h/in. In contrast sharp axial increments for electron density (Ne), whereas Ne increased from 0.9 × 109 to 20 × 109 cm-3 for 8 h/in and from 8 × 109 to 42 × 109 cm-3 for 20 h/in. Silicon wafer [100] was exposed directly behind the meshes to realize nano-particle growth in sputtering discharge, where there are two different particles shapes: spherical shape particles produced by 20 h/in, and filamentary-shaped fractal particles formed by 8 h/in. The particle radius growth for 20 h/in was in the range of 4.67 - 301 nm during exposure time 40 - 95 min, and for 8 h/in were in the range of 9.2 - 28.8 nm during exposure time 60 - 95 min.
基金This work was supported by NNSFC (No. 20671092)Science and Technology Program from Fujian Province (No. 2006J0178 and 2005HZ01-1)a grant from Hundreds Youth Talents Program of CAS (LiGS)
文摘Anatase nanoparticles modified by sulfate groups were synthesized using hydrothermal method. The particles were controlled to large sizes by simply adjusting the amount of H2O2, in which HOO^- ions replaced the surface sulfate groups and reduced the steric effect to promote the grain growth. The size-induced microstructural changes of the as-prepared nanoparticles were characterized using powder XRD, FT-IR, TG. and UV-vis analyses. The sulfate groups existed on anatase surface in unidentate and bidentate coordination forms. With the particle size reduction, bandgap energies of the as-prepared anatase nanoparticles decreased, and the desorption temperature of sulfate groups shifted towards lower temperatures.
文摘研究气液交叉流阵列内传热传质自增湿形成过饱和条件下水蒸汽在PM 2.5 颗粒表面经历异质核化凝结长大的机理,并建立颗粒长大计算模型,逐排计算,确定颗粒粒径变化量。模型分析与计算结果解释了自增湿由强到弱的阵列条件下,实验检测到的PM 2.5 颗粒粒径增长速度先增大后减小的规律。在气体温度T in =41.2℃,饱和度S R =0.85,横掠温度T w =5℃的一个单元(100排)降膜交叉阵列实验条件下,最大可达5.5μm/s的增长速度,且模型预测颗粒长大后粒径分布与实验结果吻合较好。
基金funded by the National Basic Research Program of China (2005CB422203, 2005CB422208)National Department Public Benefit Research Foundation (No.201009001)National Natural Science Foundation of China(Grant No. 41005065)
文摘Particle number size distribution from 10 to 10,000 nm was measured by a wide-range particle spectrometer （WPS-1000XP） at a downwind site north of downtown Lanzhou, western China, from 25 june to 19 July 2006. We first report the pollution level, diurnal variation of particle concentration in different size ranges and then introduce the characteristics of the particle formation processes, to show that the number concentration of ultrafine particles was lower than the values measured in other urban or suburban areas in previous studies, However, the fraction of ultrafine particles in total aerosol number concentration was found to be much higher. Furthermore, sharp increase of ultrafine particle concentration was frequently observed at noon. An examination of the diurnal pattern suggests that the burst of the ultrafine particles was mainly due to nucleation process. During the 25-day observation, new particle formation （NPF） from homogeneous nucleation was observed during 33% of the study period. The average growth rate of the newly formed particles was 4.4 nm/h, varying from 1.3 to 16,9 nm/h. The needed concentration of condensable vapor was 6.1 × 10^7 cm-3, and its source rate was 1.1× 10^6 cm-3 s 1. Further calculation on the source rate of sulphuric acid vapor indicated that the average participation of sulphuric acid to particle growth rate was 68.3%.
