Ionization efficiency is an important factor for ion sources in mass spectrometry and ion mobility spectrometry.Using helium as the discharge gas,acetone as the sample,and high-field asymmetric ion mobility spectrome...Ionization efficiency is an important factor for ion sources in mass spectrometry and ion mobility spectrometry.Using helium as the discharge gas,acetone as the sample,and high-field asymmetric ion mobility spectrometry（FAIMS） as the ion detection method,this work investigates in detail the effects of discharge parameters on the efficiency of ambient metastableinduced desorption ionization（AMDI） at atmospheric pressure.The results indicate that the discharge power and gas flow rate are both significantly correlated with the ionization efficiency.Specifically,an increase in the applied discharge power leads to a rapid increase in the ionization efficiency,which gradually reaches equilibrium due to ion saturation.Moreover,when the discharge voltage is fixed at 2.1 kV,a maximum efficiency can be achieved at the flow rate of 9.0 m/s.This study provides a foundation for the design and application of AMDI for on-line detection with mass spectrometry and ion mobility spectrometry.展开更多
Temporally-resolved spectroscopic diagnostics of dielectric barrier discharges （DBDs） in atmospheric-pressure helium was carried out to study the discharge mechanism. Using an intensified charge-coupled device （ICC...Temporally-resolved spectroscopic diagnostics of dielectric barrier discharges （DBDs） in atmospheric-pressure helium was carried out to study the discharge mechanism. Using an intensified charge-coupled device （ICCD） and a grating spectrometer, we obtained the emission spectra of homogeneous discharges and presented them in 3D graphs. We also studied the time variation of typical emissions from He, 0 and first negative bands of N＋_2. The results showedthat the spectral lines do not develop synchronously as-N_2（B_2∑U＋x2∑＋G,0～0,λ=391.4nm）and N＋2（B2∑＋u→X2∑＋g,0～1,λ=427.8nm） appear earlier and last for a longer time than He（3_3S1→2_3P1,λ=706.5nm）and O （3_P→3_5S,λ=777.4nm） A certain number of He metastables produced in the initial stage of discharge. Even between adjacent pulses, the emissions from N＋2 can still keep certain intensities while those from He and 0 extinguish. Since long-lifetime Hemetastables are produced and exist in the discharging space, it is the Penning ionization thatkeeps the long decay of N＋ emissions.展开更多
The striation plasmas are usually generated within a positive column of glow discharge,where rich and complex physical interactions are involved,especially,in the medium or high pressures.Along these lines,our work ai...The striation plasmas are usually generated within a positive column of glow discharge,where rich and complex physical interactions are involved,especially,in the medium or high pressures.Along these lines,our work aims to thoroughly investigate the formation and destruction of helium striation plasmas at kPa level pressures.The characteristics of the helium striation plasmas,and especially the optical emission properties are explored.The emission lines of 706.52 nm and391.44 nm related to the energetic electrons and the high-energy metastable helium atoms respectively,were focused on in this work.The formation of striation plasmas in a helium glow discharge,is mainly associated with the instability originating from the stepwise ionization of high-energy metastable state atoms,Maxwellization of the electron distribution functions and gas heating.Additionally,the destruction effect of helium striation plasmas is of great significance when a small amount of nitrogen or oxygen is mixed into the discharge plasmas.The reduction of the mean electron energy and the consumption of the high-energy metastable helium atoms are considered as the underlying reasons for the destruction of striation plasmas.展开更多
We conducted measurement and calculation to resolve the long-standing large discrepancy in the metastable state lifetime for the ^(88)Sr atom between theoretical and experimental results. The present lifetime τ = 830...We conducted measurement and calculation to resolve the long-standing large discrepancy in the metastable state lifetime for the ^(88)Sr atom between theoretical and experimental results. The present lifetime τ = 830_(-240)^(+600)s,measured using the magneto-optical trap as a photon amplifier to detect the weak decay events, is approximately60% larger than the previous experimental value τ = 520_(-140)^(+310)s. By considering the electron correlation effects in the framework of the multiconfiguration Dirac–Hartree–Fock theory, we obtained a theoretical lifetime of 1079(54) s, which lies in the range of measurements with error bars. Furthermore, we considered the higher-order electron correlation and Breit interaction to control the uncertainty of the theoretical calculation. The significant improvement in the agreement between calculations and measurements is attributed to the updated blackbody radiation-induced decay rate.展开更多
In this study, the density of metastable He2* in an atmospheric-pressure plasma jet operating in helium with 0.001% nitrogen has been measured using an auxiliary measuring electrode technique.In the glow discharge mod...In this study, the density of metastable He2* in an atmospheric-pressure plasma jet operating in helium with 0.001% nitrogen has been measured using an auxiliary measuring electrode technique.In the glow discharge mode, waveforms from two grounding electrodes, including one main discharge electrode and one auxiliary electrode, are captured.The isolated current peak formed by Penning ionization in waveforms from the auxiliary measuring electrode is identified to calculate the density of metastable He2*.In our discharge environment, the helium metastable densities along the jet axis direction are between 2.26×1013 and 1.74×1013 cm-3,which is in good agreement with the results measured by other techniques.This measurement technique can be conveniently applied to the diagnosis of metastable He2* in an atmospheric-pressure plasma jet array.展开更多
In this paper, the superfluid substance is described by the same equations of the electromagnetic field and the gravitational field. The gravitational mass is sufficiently considered as the gravitational charge, havin...In this paper, the superfluid substance is described by the same equations of the electromagnetic field and the gravitational field. The gravitational mass is sufficiently considered as the gravitational charge, having the same dimensions as electric charge.展开更多
This paper investigates the third series of the 2s+1 p0 helium states. The anisotropism of the electronic distribution is presented, the partial-wave compositions of the states are compared with each other, and the an...This paper investigates the third series of the 2s+1 p0 helium states. The anisotropism of the electronic distribution is presented, the partial-wave compositions of the states are compared with each other, and the angular correlation is intuitively shown by the shape-density. Two types of radial-radial correlation, namely, the "gradually push" and the "sudden transition", have been identified and the approximate symmetry with respect to the interchange of r1 and r2 has been evaluated.展开更多
COMPARED with the popular hyperspherical coordinate scheme, the HHGLF method proposed by Deng and others has the advantages of rapid hyperradial convergence, analytical solution and huge basis set calculation. However...COMPARED with the popular hyperspherical coordinate scheme, the HHGLF method proposed by Deng and others has the advantages of rapid hyperradial convergence, analytical solution and huge basis set calculation. However, the problem of slow convergence in the hyperangle part still exists as other hyperspherical harmonics (HH) methods do. To solve the prob-展开更多
基金supported by National Natural Science Foundation of China(No.61374016)the Changzhou Science and Technology Support Program,China(No.CE20120081)the External Cooperation Program of Chinese Academy of Sciences(No.GJHZ1218)
文摘Ionization efficiency is an important factor for ion sources in mass spectrometry and ion mobility spectrometry.Using helium as the discharge gas,acetone as the sample,and high-field asymmetric ion mobility spectrometry（FAIMS） as the ion detection method,this work investigates in detail the effects of discharge parameters on the efficiency of ambient metastableinduced desorption ionization（AMDI） at atmospheric pressure.The results indicate that the discharge power and gas flow rate are both significantly correlated with the ionization efficiency.Specifically,an increase in the applied discharge power leads to a rapid increase in the ionization efficiency,which gradually reaches equilibrium due to ion saturation.Moreover,when the discharge voltage is fixed at 2.1 kV,a maximum efficiency can be achieved at the flow rate of 9.0 m/s.This study provides a foundation for the design and application of AMDI for on-line detection with mass spectrometry and ion mobility spectrometry.
基金supported by National Natural Science Foundation of China(No.50807018)the State Key Laboratory of Electrical Insulation and Power Equipment(EIPE 12203)
文摘Temporally-resolved spectroscopic diagnostics of dielectric barrier discharges （DBDs） in atmospheric-pressure helium was carried out to study the discharge mechanism. Using an intensified charge-coupled device （ICCD） and a grating spectrometer, we obtained the emission spectra of homogeneous discharges and presented them in 3D graphs. We also studied the time variation of typical emissions from He, 0 and first negative bands of N＋_2. The results showedthat the spectral lines do not develop synchronously as-N_2（B_2∑U＋x2∑＋G,0～0,λ=391.4nm）and N＋2（B2∑＋u→X2∑＋g,0～1,λ=427.8nm） appear earlier and last for a longer time than He（3_3S1→2_3P1,λ=706.5nm）and O （3_P→3_5S,λ=777.4nm） A certain number of He metastables produced in the initial stage of discharge. Even between adjacent pulses, the emissions from N＋2 can still keep certain intensities while those from He and 0 extinguish. Since long-lifetime Hemetastables are produced and exist in the discharging space, it is the Penning ionization thatkeeps the long decay of N＋ emissions.
基金supported by National Natural Science Foundation of China(No.11875039)。
文摘The striation plasmas are usually generated within a positive column of glow discharge,where rich and complex physical interactions are involved,especially,in the medium or high pressures.Along these lines,our work aims to thoroughly investigate the formation and destruction of helium striation plasmas at kPa level pressures.The characteristics of the helium striation plasmas,and especially the optical emission properties are explored.The emission lines of 706.52 nm and391.44 nm related to the energetic electrons and the high-energy metastable helium atoms respectively,were focused on in this work.The formation of striation plasmas in a helium glow discharge,is mainly associated with the instability originating from the stepwise ionization of high-energy metastable state atoms,Maxwellization of the electron distribution functions and gas heating.Additionally,the destruction effect of helium striation plasmas is of great significance when a small amount of nitrogen or oxygen is mixed into the discharge plasmas.The reduction of the mean electron energy and the consumption of the high-energy metastable helium atoms are considered as the underlying reasons for the destruction of striation plasmas.
基金supported by the National Natural Science Foundation of China (Grant Nos. 11874090, 91536106, 61127901, 11404025, and U1530142)the Strategic Priority Research Program of CAS (Grant No. XDB21030100)+1 种基金the Key Research Project of Frontier Science of CAS (Grant No. QYZDB-SSW-JSC004)the West Light Foundation of CAS (Grant No. XAB2018B17)。
文摘We conducted measurement and calculation to resolve the long-standing large discrepancy in the metastable state lifetime for the ^(88)Sr atom between theoretical and experimental results. The present lifetime τ = 830_(-240)^(+600)s,measured using the magneto-optical trap as a photon amplifier to detect the weak decay events, is approximately60% larger than the previous experimental value τ = 520_(-140)^(+310)s. By considering the electron correlation effects in the framework of the multiconfiguration Dirac–Hartree–Fock theory, we obtained a theoretical lifetime of 1079(54) s, which lies in the range of measurements with error bars. Furthermore, we considered the higher-order electron correlation and Breit interaction to control the uncertainty of the theoretical calculation. The significant improvement in the agreement between calculations and measurements is attributed to the updated blackbody radiation-induced decay rate.
基金supported by National Natural Science Foundation of China (No.11105093)
文摘In this study, the density of metastable He2* in an atmospheric-pressure plasma jet operating in helium with 0.001% nitrogen has been measured using an auxiliary measuring electrode technique.In the glow discharge mode, waveforms from two grounding electrodes, including one main discharge electrode and one auxiliary electrode, are captured.The isolated current peak formed by Penning ionization in waveforms from the auxiliary measuring electrode is identified to calculate the density of metastable He2*.In our discharge environment, the helium metastable densities along the jet axis direction are between 2.26×1013 and 1.74×1013 cm-3,which is in good agreement with the results measured by other techniques.This measurement technique can be conveniently applied to the diagnosis of metastable He2* in an atmospheric-pressure plasma jet array.
文摘In this paper, the superfluid substance is described by the same equations of the electromagnetic field and the gravitational field. The gravitational mass is sufficiently considered as the gravitational charge, having the same dimensions as electric charge.
文摘This paper investigates the third series of the 2s+1 p0 helium states. The anisotropism of the electronic distribution is presented, the partial-wave compositions of the states are compared with each other, and the angular correlation is intuitively shown by the shape-density. Two types of radial-radial correlation, namely, the "gradually push" and the "sudden transition", have been identified and the approximate symmetry with respect to the interchange of r1 and r2 has been evaluated.
文摘COMPARED with the popular hyperspherical coordinate scheme, the HHGLF method proposed by Deng and others has the advantages of rapid hyperradial convergence, analytical solution and huge basis set calculation. However, the problem of slow convergence in the hyperangle part still exists as other hyperspherical harmonics (HH) methods do. To solve the prob-
