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1.
本文报道了He2 ,O2 和Ne2 与W靶表面相互作用中的动能电子产额随离子入射速度变化的实验测量结果.结果表明:在本实验的入射速度范围内,对同一入射离子,动能电子产额随入射离子的速度增大而线性增加.基于动能电子发射的机理,我们分析了影响动能电子产额的因素,理论上得出动能电子产额与入射速度增长呈线性增加的关系,取得了实验上和理论上一致的结果. 相似文献
2.
S.?Bari F.?Alvarado J.?Postma P.?Sobocinski R.?Hoekstra T.?Schlath?lter 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2009,51(1):81-87
In chromatin, DNA is tightly packed into one complex together with histone and non-histone proteins. These proteins are known
to protect the DNA against indirect and to some extent even direct radiation damage. Radiation action upon amino acids is
thus one of the primary steps in biological radiation action. In this paper we investigate the ionization and fragmentation
of the gas-phase amino acids glycine, alanine and valine upon interaction with keV α-particles. High resolution coincidence
time-of-flight mass spectrometry is used to determine the dominant fragmentation channels as well as fragment kinetic energies. 相似文献
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B. Pranszke S. Werbowy R. Miotk K. J. Borkowski A. Kowalski 《The European physical journal. Special topics》2013,222(9):2309-2315
Spectroscopic studies of collisions between He+ and He++ ions with H2 gas target have been performed in the 200–600 nm wavelength range. Atomic lines of hydrogen Balmer series and several helium lines were identified and their excitation functions between 50 eV and 1 keV (2 keV for He++) were determined. 相似文献
5.
The dependence of the intensities of atomic lines and molecular bands emitted in the afterglow of a helium discharge on the electron temperature is used to identify the processes in which states of He and He
2
*
are populated. It is established that the formation of He* atoms (n = 3, 4) in decaying helium plasma occurs principally on account of the associative recombination of vibrationally excited He
2
+
ions and electrons. Analysis of the experimental reuslts leads to the conclusion that the distribution of the molecular ions He
2
+
over vibrational states is strongly nonequilibrium.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 2, pp. 67–72, February, 1984.It remains to thank N. P. Penkin for discussions and for his interest in the work. 相似文献
6.
《Nuclear Physics A》1988,486(2):285-305
7.
利用附加电子转移因子和开关函数的半经典近似和量子分子轨道方法,在0.3~3.0 KeV能区和2.0~20.0(a.u.)核间距的条件下,对Si5+离子与He原子相互作用过程中5个singlet 态和5个triplet态的双电子捕获势能进行了理论计算.通过参数优化,在比较了基通道电子转移势能和实验值之后,研究了主通道的电子转移势能.其结果说明了这一动力学过程中的避交叉(avoided crossings)性质,给出了双电子容易被捕获的不同核间距离点. 相似文献
8.
9.
Scattering of H
3
+
ions from a clean Ni(111) surface is observed at energies below 1 keV and grazing incidence in a time-of-flight system. The interaction with the surface leads to neutral particles mainly which are identified from the energy distributions as H and H2. The neutralisation/dissociation mechanism is probably a resonant charge transfer of Ni electrons into the non-binding ground state of H3. 相似文献
10.
V. V. Afrosimov A. A. Basalaev Yu. G. Morozov M. N. Panov O. V. Smirnov E. A. Tropp 《Technical Physics》2012,57(5):594-602
The time-of-flight mass spectrometry method is used to study processes occurring when 36-keV multiply charged Ar ions (Ar6+) capture electrons from adenine and uracyl molecules. Adenine and uracyl constitute one of two base pairs entering into the RNA composition. The fragmentation scheme of resulting molecular ions is derived by analyzing correlations between the detection times of all fragment ions. Fragmentation patterns for molecular ions resulting from molecule ionization by photons, electrons, protons, and multiply charged ions are compared. 相似文献
11.
G. Guillon T. Stoecklin A. Voronin 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,46(1):83-87
We compare the cross sections for the transitions changing the projection of
the total angular momentum of N2
+(2Σ) in collisions
with 3He and 4He at very low collision energy. The fundamental
states of the two nuclear spin isomers of N2
+ are considered as
well as the two fine structure levels of the first excited para level N=2.
It is shown that the two fundamental states of the two nuclear spin isomers
behave differently. For the fundamental para level N=0 of N2
+, the
projection changing cross section is always negligible compared to the
elastic one for both He isotopes. For the fundamental ortho level N=1 of
N2
+, the spin-rotation interaction couples the different spin
levels directly so the spin relaxation becomes a first order process. The
associated resonances increase the projection changing cross section which
remains smaller but becomes comparable with the elastic one. This is in
contrast with the excited rotational levels of N2
+, which for the
rotational deactivation and elastic channels are found to be equal around
the resonances for the collisions involving 3He. These two channels are
always larger than the projection changing one. We also find that, for
transitions involving the fundamental rotational state, the domain of
validity of the threshold laws discussed by Krems and Dalgarno [Phys. Rev. A 67, 050704 (2003)] for a potential decreasing faster than
1/r2 is shortened, due to the long range charge induced dipole potential.
This effect is illustrated for the collisions of 3He with the
fundamental para state of N2
+. 相似文献
12.
I. M. Krygin A. D. Prokhorov V. P. D’yakonov M. T. Borowiec H. Szymczak 《Physics of the Solid State》2002,44(8):1587-1596
The spin-spin interaction of Dy3+ ions in a KY(WO4)2 single crystal is investigated by electron paramagnetic resonance (EPR) spectroscopy at a temperature of 4.2 K and a frequency of 9.2 GHz. The EPR spectra of ion pairs located in different coordination shells are analyzed. It is revealed that the considerable contribution to the spin-spin interaction of the nearest neighbor ion pair nn is made not only by the magnetic dipole-dipole interaction but also by the isotropic exchange interaction with the parameter I nn = (+601 ± 17) × 10?4cm?1. The exchange interaction in pairs of more widely spaced ions is substantially weaker: I 5n = (?38 ± 3) × 10?4cm?1 and I 9n = (+18 ± 4) × 10?4cm?1. For the other ion pairs, the magnetic dipole-dipole interaction dominates. It is found that the EPR spectra of single ions and ion pairs exhibit a superhyperfine structure associated with tungsten nuclei. 相似文献
13.
A. Yu. Chirkov 《Technical Physics》2006,51(9):1158-1162
Possible operating regimes of a spherical tokamak reactor based on the D-3He fuel cycle with 3He production are considered. The parameters of the plasma and magnetic system are calculated for several versions corresponding to the high power efficiency (with a power gain factor in plasma of Q = 20) in a reactor with an aspect ratio of A = 1.5. According to calculations, for an axial magnetic field in vacuum of B 0 = 2 T, a plasma radius of a = 3 m, an average 〈β〉 value of 0.53, and a plasma temperature of 〈T〉 = 48 keV, the reactor power can reach P fus = 500 MW. In order to achieve a power of P fus = 1500 MW in a reactor with a = 2 m, 〈β〉 = 0.36, and 〈T〉 = 40 keV, the magnetic field should be increased to B 0 = 5 T. 相似文献
14.
Y. Aratono C. Sagawa M. Nakashima M. Nakada K. Hojou M. Saeki 《Hyperfine Interactions》1992,70(1-4):905-908
The chemical reactions induced by 40 keV He+ ions in α-Fe2O3 and Fe3O4 were investigated by the conversion electron Mössbauer spectroscopy(CEMS). Magnetite(Fe3O4) was formed upon the bombardment of α-Fe2O3, whereas no change was observed in Fe3O4. The initial G value for Fe3O4 formation is estimated to be 3.5×10?4 for 100 nm depth from the surface. The application of CEMS and sputtering technique to ion bombardment chemistry is discussed. 相似文献
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17.
Gisèle Cory-Goulard 《Czechoslovak Journal of Physics》1986,36(8):971-975
Experimental measurements and theoretical calculations are discussed for theA = 3 nuclei. With the sum rule formalism, the need for a better bound state is investigated. Some reactions on3He and3H like electron scattering, photodisintegration,-capture involve transitions to the continuum but with the work developed by Merkuriev, Gignoux and Laverne (1976) some progress is possible. The same realisticNN interactions used for calculating the bound state wave function of the three nucleon system are incorporated in the scattering equations based on the Faddeev approach.Presented at the symposium Mesons and Light Nuclei, Bechyn, Czechoslovakia, May 27–June 1, 1985. 相似文献
18.
The absolute cross section for the fragmentation of positronium in collision with He atoms has been measured. The results are compared with available theories. The longitudinal energy distributions of positrons resulting from fragmentation have also been determined and are found to display a peak situated just below half the residual energy. This is suggestive of the occurrence of "electron loss to the continuum" in which the two residual charged particles lie in a low relative-velocity Coulomb-continuum state. 相似文献
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20.
Guyer RA 《Physical review letters》1990,64(16):1919-1923