共查询到20条相似文献,搜索用时 15 毫秒
1.
K. Sekimoto M. Takayama 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2010,60(3):589-599
The change in the distribution pattern of negative ions HO–, NOx-_{x}^{-} and COx-_{x}^{-} observed on arbitrary point-to-plane electrode configuration has been investigated by varying the angle of needle to the
plane electrode, under atmospheric pressure corona discharge
conditions. The stationary inhomogeneous electric field distributions between the point-to-plane electrodes with arbitrary
needle angle were calculated. The experimental and theoretical results obtained suggested that the negative ion evolutions
progress along field lines established between
the electrodes with arbitrary configurations and the resulting terminal ion formation on a given field line is attributable
to the electric field strength on the needle tip surface where the field line arose. The NOx-_{x}^{-} and COx-_{x}^{-} ions were dominantly produced on the field lines arising from the needle tip apex region with the highest electric field
strength, while the field lines emanating from the tip peripheral regions with lower field strength resulted in the formation
of the HO– ion. 相似文献
2.
The surface deposits of the traces stained with discharges on the brass plate electrode in atmospheric pressure DC negative corona have been analyzed. The surface analysis showed that the major deposits on the traces originate from nitrogen oxide ions NOx? and neutrals NOx, or carbon clusters Cn. The relationship between the plane positions and resulting deposits obtained with the point-to-plane electrodes with arbitrary needle angle to the plane provided the information about the general behavior of negative ions NOx? and neutral species NOx occurring in stationary inhomogeneous electric fields. 相似文献
3.
Based on closed-orbit theory, the photodetachment of H in a gradient electric field near a metal surface is studied. It is demonstrated that the gradient electric field has a significant influence on the photodetachment of negative ions near a metal surface. With the increase of the gradient of the electric field, the oscillation in the photodetachment cross section becomes strengthened. Besides, in contrast to the photodetachment of H near a metal surface in a uniform electric field, the oscillating amplitude and the oscillating region in the cross section of a gradient electric field also become enlarged. Therefore, we can use the gradient electric field to control the photodetachment of negative ions near a metal surface. We hope that our results will be useful for understanding the photodetachment of negative ions in the vicinity of surfaces, cavities, and ion traps. 相似文献
4.
R. F.M. Lobo N. T. Silva B. M.N. Vicente I. M.V. Gouveia F. M.V. Berardo J. H.F. Ribeiro 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2006,38(1):35-45
The crossed molecular beam technique is used for producing C60- species through potassium-buckyball collision processes, and studying the collision dynamics in an energy ranging from 10 eV
up to 500 eV. At low collision energies only the negative parent ion is formed. As long as the collision energy is increased
the fragmentation pattern of the fullerene negative ion could be identified and relative total cross-sections could be measured.
Surprisingly, some satellite contributions have been observed in the band structure of C60- parent ion time-of-flight spectrum, which points to the existence of distinct conformational C60- isomers, which are likely to be formed during the collision, favoured by the strong polarization of the C60- in the presence of the K+ projectile ion. Such presumed detection of different spheroidal metastable C60- conformers was made possible due to an electric effect operating at the nanoscale. 相似文献
5.
6.
W. G. Wang Y. Xu X. F. Yang A. M. Zhu Z. W. Liu X. Liu 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,46(1):103-109
Rovibrational excited hydrogen molecule plays an important role for the
production of H- ions. The correlation between H- ion density and
rovibrational distribution of H2 molecules has been investigated in
dielectric barrier discharge hydrogen plasmas via optical emission
spectrometry and molecular beam mass spectrometry. The relative vibrational
distribution of molecular hydrogen in the electronic ground state has been
determined by the best fitting to the Fulcher-α band emission
lines. It is shown that the ratio of the Q(0-0)(1) to Q(1-1)(1)
line is very suitable and simple for the diagnosis of vibrational
temperature in the range of 1500 to 7500 K. At certain discharge conditions
(ac 40 kHz, 14 kV), the vibrational temperature decreases from 3600 to
2400 K as the pressure increases from 100 to 200 Pa and the negative ions
density near the ground electrode also decreases as the pressure increases.
Both the hydrogen ions density and the vibrational temperature increase with
the increasing of discharge voltage. It is found that the evolution of
negative atomic hydrogen ions density greatly depends on the vibrational
temperature. 相似文献
7.
G. Durand F. Spiegelman A. R. Allouche 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,24(1-3):19-22
Recently, electric susceptibilities of
NanFn-1 clusters
have been measured by deflecting a molecular beam in an
inhomogeneous electric field. The analysis of the deflection of
a cluster by the electric field needs the calculation of the
electric properties. We present the calculation of the static
anisotropic and average dipolar polarizabilities within a model
in which the
NanFn-1 clusters (
2
n
23)
are treated as one electron embedded in the field of
n ions
Na+ and of n
- 1
ions F-. The accuracy of the results
is evaluated and discussed on small clusters (n
5)
in comparison with ab initio
calculations. The relationship between the polarizabilities, the
electronic localization and the geometric structure is
discussed. Received 10 September 2002 Published online 3 July
2003 相似文献
8.
Magnetic field effect in photodetachment from negative ion in electric field near metal surface 下载免费PDF全文
Based on the closed-orbit theory, the magnetic field effect in the photodetachment of negative ion in the electric field near a metal surface is studied for the first time. The results show that the magnetic field can produce a significant effect on the photodetachment of negative ion near a metal surface. Besides the closed orbits previously found by Du et al. for the H in the electric field near a metal surface (J. Phys. B 43 035002 (2010)), some additional closed orbits are produced due to the effect of magnetic field. For a given ion-surface distance and an electric field strength, the cross section depends sensitively on the magnetic field strength. As the magnetic field strength is very small, its influence can be neglected. With the increase of the magnetic field strength, the number of the closed orbits increases greatly and the oscillation in the cross section becomes much more complex. Therefore we can control the photodetachment cross section of the negative ion by changing the magnetic field strength. We hope that our results may guide future experimental studies for the photodetachment process of negative ion in the presence of external fields and surfaces. 相似文献
9.
D. N. Sinel’nikov D. V. Ivanov V. A. Kurnaev N. V. Mamedov 《Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques》2012,6(4):673-677
The electric field strength in the near-wall layers of thermonuclear facilities can be sufficient for the emission of negative ions from the surface of plasma facing materials. The mass spectra of negative ions from MPG-8 porous graphite at electric field strengths up to 4 × 106 V/m and the surface composition of the target have been studied by ion scattering spectroscopy. The dependence of the mass composition of negative ion emission and residual gas on the sample’s temperature has been measured and a correlation between the intensity of negative hydrogen-ion emission and the desorption of water has been established. The temperature dependence of the emission of negative ions and clusters of carbon and hydrocarbon is in qualitative agreement with the chemical erosion of graphite. 相似文献
10.
Laser-induced etching of polycrystalline Al2O3TiC material by tightly focused CW Ar ion laser has been investigated in both H3PO4 and KOH solutions with influence of an external electric field. It is found that a weak external electric field will change the ions distribution in chemical solutions and cause obvious change in etching behavior. The laser etching in a H3PO4 solution can be enhanced by both positive and negative biases of the substrate. While etching in a KOH solution, a positive bias can enhance the etching reaction, whereas a negative bias can suppress the etching process. It is also found that the external electric field can always enhance the mass transfer between reaction products and fresh etchant in a H3PO4 solution. It is revealed that the supply of H+ ions contributes to the etching process in a H3PO4 solution, while the supply of OH– ions contributes to the etching process in a KOH solution. The electric field can be used to control the etching process to achieve fast tuning and higher accuracy. 相似文献
11.
Photodetachment microscopy of the hydrogen negative ion in electric field near a metal surface 下载免费PDF全文
According to the semi-classical theory, we study the photodetachment microscopy of H- in the electric field near a metal surface. During the photodetachment, the electron is photo-detached by a laser and the electron is drawn toward a position-sensitive detector. The electron flux distribution is measured as a function of position. Two classical paths lead the ion to any point in the classically allowed region on the detector, and waves traveling along these paths produce an interference pattern. If the metal surface perpendicular to the electric field is added, we find that the interference pattern is related not only to the electron energy and the electric-field strength, but also to the ion--surface distance. Besides, the laser polarization also has a great influence on the electron flux distribution. We present calculations predicting the interference pattern that may be seen in experiment. We hope that our study can provide a new understanding of the electron flux distribution of negative ions in external field and surface, and can guide the future experimental research on the negative ion photo-detachment microscopy. 相似文献
12.
We present theoretical analyses of anisotropic lattice diamagnetism, magnetization due to magnetic ions and carrier spin-polarization
in the diluted magnetic semiconductor, Pb1-x
Eu
x
Te. The lattice diamagnetism results from orbital susceptibility due to inter band effects and spin-orbit contributions. The
spin-orbit contribution is found to be dominant. However, both the contributions show pronounced anisotropy. With increase
in x, the diamagnetism decreases. We consider contributions from randomly distributed isolated magnetic ions and clusters of pairs
and triads for the local moment magnetization. The isolated magnetic-ion contribution is the dominant one.We calculate the
magnetization for two typical magnetic ion concentrations: x=0.03 and x=0.06. Temperature dependence of the magnetization is also considered. Apart from lattice and localized magnetic ions, the
carrier contribution to the spin-density is also calculated for a carrier density of p=1018 cm−3. the relative spin-density of carriers increases with increase in the magnetic field strength and magnetic ion concentration.
The agreement with experiment where available is reasonably good. 相似文献
13.
Both magnetic and electric field dependences of transport coefficients are investigated on the layered material Ti1-xVxSe2 (x = 0.01). In contrast to semimetallic TiSe2, the resistivity of the V-doped samples increases with decrease of temperature even in the low temperature region. At liquid helium temperatures it is found that the resistivity is strongly dependent on electric field strength. The behaviour of the nonlinear conduction is similar to that observed in 1T-TaS2. In the low field (Ohmic) region anomalously large negative mangetoresistance is observed, Δ?/?0 = -80% at 1.6 K and 60 KOe. Moreover the Hall coefficient is also found to depend on both magnetic and electric fields. All the experimental data suggests that mobile carriers are excited by the applied fields. 相似文献
14.
Xiangdong Meng Haibo Li Liu Mei Xiao Li 《Journal of magnetism and magnetic materials》2009,321(9):1155-1158
Mössbauer spectroscopy is used to characterize the crystallite size and structure of CoFe2−xYxO4 (x=0, 0.1, 0.3, 0.5) ferrite nanocrystallites synthesized by the sol-gel auto-combustion method. The effect of the substitution of Fe3+ ions by Y3+ ions on the structure of cobalt ferrite nanocrystallites is investigated. The Mössbauer spectra showed two sets of six-line hyperfine patterns for all the samples, indicating the presence of Fe in both A and B-sites. On increasing the concentration of doped Y, the hyperfine field strength and the isomer shift first increase and then decrease, whereas the quadrupole splitting continuously increases. The superparamagnetism was observed for all the samples and the change of ratio of the superparamagnetism component reflects the size of crystal grain. 相似文献
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17.
A. John Peter K. Lily Mary Eucharista 《Journal of magnetism and magnetic materials》2009,321(5):402-407
We report the effect of intense laser field on donor impurities in a semimagnetic Cd1-xinMnxinTe/Cd1-xoutMnxoutTe quantum dot. The spin polaronic energy of different Mn2+ is evaluated for different dot radii using a mean field theory in the presence of laser field. Magnetization is calculated for various concentrations of Mn2+ ions with different dot sizes. Significant magnetization of Mn spins can be obtained through the formation of polarized exciton magnetic polarons (EMPs). A rapid decrease of the laser dressed donor ionization energy for different values of dot sizes with increasing field intensity is predicted. Also, it is found that the polarization of EMPs increases rapidly at higher excitation energies. 相似文献
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19.
采用聚苯乙烯小球修饰Ti片表面,并进行阳极氧化,制备出一种由纳米颗粒和纳米管构成的TiO2膜.通过数值模拟,分析了氧化表面附近的局部电场分布对TiO2膜形貌的影响.结果表明,覆盖物增强了局部电场,从而加快了O2-与Ti的反应速率,有利于TiO2的生长;与此同时,[TiF6]6-的扩散受到阻碍,使得TiO2的溶解速率减慢.可见,覆盖物打破了TiO2纳米管形成的平衡条件,导致纳米颗粒的生成.此外,通过X射线衍射和Raman光谱的测试分析发现,所制备的TiO2为锐钛矿结构. 相似文献
20.
T. Kato M. Kurata-Nishimura T. Kobayashi Y. Okamura-Oho T. Sano Y. Hayashizaki Y. Matsuo J. Kawai 《Applied Physics A: Materials Science & Processing》2008,92(4):809-812
In order to develop a femtosecond laser ablation (fsLA) ion source for TOF mass spectrometry, we have analyzed time-resolved
images of laser-induced fluorescence from Sm+ ions produced by fsLA of a solid samarium in electric fields. The polarity and the strength of electric fields had a remarkable
effect on the expansion of Sm+ ions. Moreover, accelerating electric fields elongated the duration of the ion emission from the samarium surface in fsLA,
which degraded time-focusing of the ions. We have found that suppression the continuous ion emission caused by fsLA in electric
fields is most important in TOF measurements. 相似文献