High field asymmetric wave ion mobility spectrometry （FAIMS） is a powerful tool to detect and characterize gas-phase ions, while the unsolvable partial differential equation of ions moving in ion drift tube poses a ...High field asymmetric wave ion mobility spectrometry （FAIMS） is a powerful tool to detect and characterize gas-phase ions, while the unsolvable partial differential equation of ions moving in ion drift tube poses a big challenge to FAIMS spectral peak analysis. In this work, a universal and effective model of FAIMS spectral peak profile has been proposed by introducing ion trajectory and loss height. With this model, the influence of the structure of ion drift tube, dispersion voltages, compensation voltages, and carrier gas flow rate on the FAIMS spectral peak characteristics like peak shape, full width at half maximum and peak height is analyzed and discussed. The results show that the influence of different factors on the FAIMS spectral peak profile can be qualitatively described by the model which agrees with the experimental data.展开更多
In this paper,we introduce a method of quantitatively evaluating and controlling the space charge effect of a lasercooled three-dimensional（3 D） ion system in a linear Paul trap.The relationship among cooling effici...In this paper,we introduce a method of quantitatively evaluating and controlling the space charge effect of a lasercooled three-dimensional（3 D） ion system in a linear Paul trap.The relationship among cooling efficiency,ion quantity,and trapping strength is analyzed quantitatively,and the dynamic space distribution and temporal evolution of the 3 D ion system on a secular motion period time scale in the cooling process are obtained.The ion number influences the eigen-micromotion feature of the ion system.When trapping parameter q is ～ 0.3,relatively ideal cooling efficiency and equilibrium temperature can be obtained.The decrease of axial electrostatic potential is helpful in reducing the micromotion heating effect and the degradation in the total energy.Within a single secular motion period under different cooling conditions,ions transform from the cloud state（each ion disperses throughout the envelope of the ion system） to the liquid state（each ion is concentrated at a specific location in the ion system） and then to the crystal state（each ion is subjected to a fixed motion track）.These results are conducive to long-term storage and precise control,motion effect suppression,high-efficiency cooling,and increasing the precision of spectroscopy for a 3 D ion system.展开更多
In January 2013, a long-lasting severe haze episode occurred in Northern and Central China; at its maximum, it covered a land area of approximately 1.4 million km2. In Wuhan, the largest city in Central China, this ev...In January 2013, a long-lasting severe haze episode occurred in Northern and Central China; at its maximum, it covered a land area of approximately 1.4 million km2. In Wuhan, the largest city in Central China, this event was the most severe haze episode in the 21st century. Aerosol samples of submicron particles （PMI.o） were collected during the long-lasting haze episode at an urban site and a suburban site in Wuhan to investigate the ion characteristics of PMi.0 in this area. The mass concentrations of PM1.0 and its water-soluble inorganic ions （WSIIs） were almost at the same levels at two sites, which indicates that PM1.0 pollution occurs on a regional scale in Wuhao. WSIIs （Na^＋, NH4^＋, K^＋, Mg^2＋, Ca^2＋, Cl^-, NO3 and SO2-） were the dominant chemical species and constituted up to 48.4% and 47.4% of PM1.0 at WD and TH, respectively. The concentrations of PM1.0 and WSIIs on haze days were approximately two times higher than on normal days. The ion balance calculations indicate that the particles were more acidic on haze days than on normal days. The results of the back trajectory analysis imply that the high concentrations of PM1.0 and its water-soluble inorganic ions may be caused by stagnant weather conditions in Wuhan.展开更多
PM（2.5） samples were collected in Zhengzhou during 3 years of observation, and chemical characteristics and source contribution were analyzed. Approximately 96% of the daily PM（2.5） concentrations and annual avera...PM（2.5） samples were collected in Zhengzhou during 3 years of observation, and chemical characteristics and source contribution were analyzed. Approximately 96% of the daily PM（2.5） concentrations and annual average values exceeded the Chinese National Ambient Air Quality Daily and Annual Standards, indicating serious PM（2.5） pollution. The average concentration of water-soluble inorganic ions was 2.4 times higher in heavily polluted days（daily PM32.5 concentrations ＆gt; 250 μg/mand visibility ＆lt; 3 km） than that in other days, with sulfate, nitrate, and ammonium as major ions. According to the ratio of NO-3/SO2-4,stationary sources are still the dominant source of PM（2.5） and vehicle emission could not be ignored. The ratio of secondary organic carbon to organic carbon indicated that photochemical reactivity in heavily polluted days was more intense than in other days.Crustal elements were the most abundant elements, accounting for more than 60% of 23 elements. Chemical Mass Balance results indicated that the contributions of major sources（i.e., nitrate, sulfate, biomass, carbon and refractory material, coal combustion, soil dust,vehicle, and industry） of PM（2.5） were 13%, 16%, 12%, 2%, 14%, 8%, 7%, and 8% in heavily polluted days and 20%, 18%, 9%, 2%, 27%, 14%, 15%, and 9% in other days, respectively.Extensive combustion activities were the main sources of polycyclic aromatic hydrocarbons during the episode（Jan 1-9, 2015） and the total benzo[a]pyrene equivalency concentrations in heavily polluted days present significant health threat. Because of the effect of regional transport, the pollution level of PM（2.5） in the study area was aggravated.展开更多
The characteristics of ion beam extraction and focused to a volume as small as possible were investigated with the aid of computer code SIMION 3D version 7. This has been used to evaluate the extraction characteristi...The characteristics of ion beam extraction and focused to a volume as small as possible were investigated with the aid of computer code SIMION 3D version 7. This has been used to evaluate the extraction characteristics （accel-decel system） to generate an ion beam with low beam emittance and high brightness. The simulation process can provide a good study for optimizing the extraction and focusing system of the ion beam without any losses and transported to the required target. Also, a study of a simulation model for the extraction system of the ion source was used to describe the possible plasma boundary curvatures during the ion extraction that may be affected by the change in an extraction potential with a constant plasma density meniscus.展开更多
基金This work was supported by the National Natural Science Foundation of China （No.60871037 andNo.61004133） and the Innovation and Technology Fund of Hefei Institutes of Physical Science.
文摘High field asymmetric wave ion mobility spectrometry （FAIMS） is a powerful tool to detect and characterize gas-phase ions, while the unsolvable partial differential equation of ions moving in ion drift tube poses a big challenge to FAIMS spectral peak analysis. In this work, a universal and effective model of FAIMS spectral peak profile has been proposed by introducing ion trajectory and loss height. With this model, the influence of the structure of ion drift tube, dispersion voltages, compensation voltages, and carrier gas flow rate on the FAIMS spectral peak characteristics like peak shape, full width at half maximum and peak height is analyzed and discussed. The results show that the influence of different factors on the FAIMS spectral peak profile can be qualitatively described by the model which agrees with the experimental data.
基金Project supported by the National Key Research and Development Program of China(Grant No.2017YFA0304401)the National Natural Science Foundation of China(Grant Nos.11622434,11474318,91336211,and 11634013)+2 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB21030100)Hubei Province Science Fund for Distinguished Young Scholars(Grant No.2017CFA040)the Youth Innovation Promotion Association of the Chinese Academy of Sciences(Grant No.2015274)
文摘In this paper,we introduce a method of quantitatively evaluating and controlling the space charge effect of a lasercooled three-dimensional（3 D） ion system in a linear Paul trap.The relationship among cooling efficiency,ion quantity,and trapping strength is analyzed quantitatively,and the dynamic space distribution and temporal evolution of the 3 D ion system on a secular motion period time scale in the cooling process are obtained.The ion number influences the eigen-micromotion feature of the ion system.When trapping parameter q is ～ 0.3,relatively ideal cooling efficiency and equilibrium temperature can be obtained.The decrease of axial electrostatic potential is helpful in reducing the micromotion heating effect and the degradation in the total energy.Within a single secular motion period under different cooling conditions,ions transform from the cloud state（each ion disperses throughout the envelope of the ion system） to the liquid state（each ion is concentrated at a specific location in the ion system） and then to the crystal state（each ion is subjected to a fixed motion track）.These results are conducive to long-term storage and precise control,motion effect suppression,high-efficiency cooling,and increasing the precision of spectroscopy for a 3 D ion system.
基金supported by the Natural Science Foundation of China(No.41103061)the Doctoral Fund Project of the Ministry of Education of China(No.20110141120015)the National Basic Research Programme(973)of China(No.2011CB707106)
文摘In January 2013, a long-lasting severe haze episode occurred in Northern and Central China; at its maximum, it covered a land area of approximately 1.4 million km2. In Wuhan, the largest city in Central China, this event was the most severe haze episode in the 21st century. Aerosol samples of submicron particles （PMI.o） were collected during the long-lasting haze episode at an urban site and a suburban site in Wuhan to investigate the ion characteristics of PMi.0 in this area. The mass concentrations of PM1.0 and its water-soluble inorganic ions （WSIIs） were almost at the same levels at two sites, which indicates that PM1.0 pollution occurs on a regional scale in Wuhao. WSIIs （Na^＋, NH4^＋, K^＋, Mg^2＋, Ca^2＋, Cl^-, NO3 and SO2-） were the dominant chemical species and constituted up to 48.4% and 47.4% of PM1.0 at WD and TH, respectively. The concentrations of PM1.0 and WSIIs on haze days were approximately two times higher than on normal days. The ion balance calculations indicate that the particles were more acidic on haze days than on normal days. The results of the back trajectory analysis imply that the high concentrations of PM1.0 and its water-soluble inorganic ions may be caused by stagnant weather conditions in Wuhan.
基金supported by the public welfare projects from MEPPRC (No. 201409010)
文摘PM（2.5） samples were collected in Zhengzhou during 3 years of observation, and chemical characteristics and source contribution were analyzed. Approximately 96% of the daily PM（2.5） concentrations and annual average values exceeded the Chinese National Ambient Air Quality Daily and Annual Standards, indicating serious PM（2.5） pollution. The average concentration of water-soluble inorganic ions was 2.4 times higher in heavily polluted days（daily PM32.5 concentrations ＆gt; 250 μg/mand visibility ＆lt; 3 km） than that in other days, with sulfate, nitrate, and ammonium as major ions. According to the ratio of NO-3/SO2-4,stationary sources are still the dominant source of PM（2.5） and vehicle emission could not be ignored. The ratio of secondary organic carbon to organic carbon indicated that photochemical reactivity in heavily polluted days was more intense than in other days.Crustal elements were the most abundant elements, accounting for more than 60% of 23 elements. Chemical Mass Balance results indicated that the contributions of major sources（i.e., nitrate, sulfate, biomass, carbon and refractory material, coal combustion, soil dust,vehicle, and industry） of PM（2.5） were 13%, 16%, 12%, 2%, 14%, 8%, 7%, and 8% in heavily polluted days and 20%, 18%, 9%, 2%, 27%, 14%, 15%, and 9% in other days, respectively.Extensive combustion activities were the main sources of polycyclic aromatic hydrocarbons during the episode（Jan 1-9, 2015） and the total benzo[a]pyrene equivalency concentrations in heavily polluted days present significant health threat. Because of the effect of regional transport, the pollution level of PM（2.5） in the study area was aggravated.
文摘The characteristics of ion beam extraction and focused to a volume as small as possible were investigated with the aid of computer code SIMION 3D version 7. This has been used to evaluate the extraction characteristics （accel-decel system） to generate an ion beam with low beam emittance and high brightness. The simulation process can provide a good study for optimizing the extraction and focusing system of the ion beam without any losses and transported to the required target. Also, a study of a simulation model for the extraction system of the ion source was used to describe the possible plasma boundary curvatures during the ion extraction that may be affected by the change in an extraction potential with a constant plasma density meniscus.
