共查询到20条相似文献,搜索用时 31 毫秒
1.
V. V. Afrosimov A. A. Basalaev K. V. Kashnikov M. N. Panov 《Physics of the Solid State》2002,44(3):509-510
This paper reports on the first measurements of the differential cross sections (with respect to scattering angle) of various elementary processes accompanying electron capture by keV-range H+ and He2+ ions from a fullerene molecule. Estimation of the impact parameter from the ion scattering angle in the polarization interaction with a fullerene molecule shows that the processes of capture and capture with fullerene ionization and fragmentation occur primarily at impact parameters far exceeding the fullerene radius. 相似文献
2.
V. V. Afrosimov A. A. Basalaev V. V. Kuz’michev M. N. Panov O. V. Smirnov 《Technical Physics》2016,61(3):342-348
The relative cross sections of elementary processes occurring in single collisions of tryptophan molecules in the gaseous phase with He2+ ions with energy 4 keV/u are measured using time-of-flight mass spectrometry for studying the mechanism of radiation damage of amino acid molecules. The fragmentation channels for intermediate singly and doubly charged tryptophan molecular ions formed during one-electron capture, two-electron capture, and electron capture with ionization are investigated. Significant difference is observed in the mass spectra of fragmentation of intermediate doubly charged ions formed during the capture with ionization and double capture, which is associated with different energies of excitation of {C11H12N2O2}2+* ions. 相似文献
3.
V. V. Afrosimov A. A. Basalaev Yu. G. Morozov M. N. Panov O. V. Smirnov E. A. Tropp 《Technical Physics》2011,56(5):597-604
Time-of-flight mass spectroscopy methods are employed for studying processes occurring during capture of electrons by 3He2+ and Ar6+ multiply charged ions with energy 6z keV (z is the ion charge) from C2H
n
molecules (n = 2, 4, 6) with different multiplicities of C-C bonds. Fragmentation schemes of the molecular ions formed in such processes
are established from analysis of correlations of recording times for all fragment ions. The absolute values of the cross sections
of capture of an electron and capture with ionization are measured, as well as the cross sections of formation of fragment
ions in these processes. The absolute values of total capture cross sections for several electrons are determined. 相似文献
4.
V. V. Afrosimov L. A. Baranova A. A. Basalaev M. N. Panov O. V. Smirnov A. V. Tulub 《Technical Physics》2010,55(3):357-366
The subject of investigation is the fragmentation of variously charged molecular ions arising in col-lisions of several kiloelectronvolt
H+, He2+, and Ar6+ ions with molecules of the simplest alkanes (from methane to butane). Using the method of time-of-flight mass spectrometry,
the formation cross sections of dissociation-induced fragment ions are measured. The dissociation takes place when an incident
ion captures an electron from a methane, ethane, or propane molecule. The role of additional ionization of the molecule, which
accompanies the electron capture by the incident ion, is elucidated. The kinetic energy spectrum for protons resulting from
the fragmentation of multiply charged alkane ions is determined. The most plausible kinetic energies of protons depending
on the degree of ionization and molecule size fall into the range 1–25 eV. It is shown that, when the molecule loses several
electrons, the kinetic energies of protons are governed by Coulomb interaction between all fragment ions and are determined
by their flying apart from the relative spatial arrangement of corresponding atoms in a parent molecule. 相似文献
5.
A. N. Perumal D. N. Tripathi 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2000,8(2):169-176
Classical Trajectory Monte-Carlo (CTMC) method has been used to investigate state selective electron capture by He2+ ions colliding with Li(2s) and Li(2p) in as well as alignments in the energy range 1-15 keV/amu. He+(4l) electron capture, line emission [He II(n = 4 3)] cross-sections and alignment parameters have been calculated and analyzed in the light of the available results. The
undulatory structure of the capture and emission cross-sections have been explained qualitatively in terms of a quasi-molecular
ion formation. Projectile impact energy and spatial overlap play crucial role in determining the alignment effects.
Received 3 July 1998 and Received in final form 3 June 1999 相似文献
6.
J. de Vries R. Hoekstra R. Morgenstern T. Schlathölter 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,24(1-3):161-164
Ionization and fragmentation of the DNA base thymine upon
interaction with keV Cq+ ions
(q
= 1 -
6) has been studied. By means of time-of-flight
spectrometry of two or more thymine fragments in coincidence
with an ejected electron we could investigate particular
dissociation channels by means of their associated
kinetic-energy-release. The fragmentation dynamics are strongly
influenced by the Cq+ charge state:
for low q values mainly
fragmentation due to direct collisions is observed. With
increasing q, electron capture
becomes more important. For larger q we could identify several Coulomb
explosion channels, leading to very energetic fragments. 相似文献
7.
V. V. Afrosimov A. A. Basalaev Yu. G. Morozov M. N. Panov O. V. Smirnov E. A. Tropp 《Technical Physics》2013,58(9):1243-1250
The relative cross sections of processes taking place when H+ and He2+ ions with an energy of 6z keV (z is the ionic charge) capture an electron from molecules of C5H11NO2S methionine (proteogenic amino acid) and C6H13NO2 norleucine (nonproteogenic amino acid) are measured by time-of-flight mass spectrometry (a methionine molecule transforms into a norleucine molecule by substituting the CH2 group for the S heteroatom). The fragmentation pattern of resulting molecular ions is established from correlation analysis of the detection times of all fragment ions. The results are compared with experimental data for fragmentation of the same molecules ionized by electrons and photons. In these amino acids, the pattern of molecular ion fragmentation is found to depend on the type of molecule ionization. However, the detachment cross section of the COOH neutral group or residue (neutral or charged) R of a side chain of the amino acid is invariably among the largest. The relative cross sections of capture with single and double ionization of molecules are measured. 相似文献
8.
We have measured the absolute values of the total cross section of the one-electron capture by He2+ ions in the kinetic energy range 2–30 keV at the Ar atoms. The absolute values of the differential scattering cross sections of He+ ions formed during the one-electron capture and the electron capture with ionization at energies of 2.2, 5.4, and 30 keV have been determined. The electronic states of the formed ions have been determined using collision spectroscopy based on analysis of the change in the kinetic energy of He+ after the interaction. We have measured doubly differential (with respect to the kinetic energy and the scattering angle) cross sections of the formation of free electrons. The free electron formation channels (direct ionization and electron capture with ionization) have been analyzed by calculating the electron terms of the (HeAr)2+ system. The calculated cross section of capture with ionization is in conformity with the cross section measured using collision spectroscopy. 相似文献
9.
Employing the dynamic crossed-beams technique, the absolute cross sections of the electron-impact multiple ionization and fragmentation of mass-selected negatively charged fullerene ions C m ? → C m?n 2+ (m=60, 70, 84; q=1, 2, 3; n=0, 2, 4) were measured. The electron energy varied from the respective threshold up to 1 keV. A scaling law was observed for the cross-section magnitude as a function of the fullerene size m and the charge state q of product ions. The data indicate that different mechanisms account for the detachment of an extra electron from the negatively charged fullerene and the formation of a positively charged ion, respectively. Moreover, the multiple ionization of a fullerene anion is found to be a sequential process. A novel ionization mechanism is proposed which might be expected to be valid for all negatively charged molecular or cluster ions able to shield the attached electron from the incident electron. 相似文献
10.
O. V. Smirnov A. A. Basalaev V. M. Boitsov S. Yu. Vyaz’min A. L. Orbeli M. V. Dubina 《Technical Physics》2014,59(11):1698-1704
The relative cross section of processes attendant on the capture of an electron by 12-keV 3He2+ ions are measured by time-of-flight mass spectrometry for leucine (C6H13NO2), methionine (C5H11NO2S), and glutmic acid (C5H9NO4) molecules. No differences between the formation relative cross sections of different fragment ions for the D- and L-enantiomeric forms of the amino acids are revealed. The spectrum of glutamic acid fragments taken at temperatures above 110°C is explained by decomposition of the acid with the formation of pyroglutamic acid (C5H7NO3) and water. The results are compared with published data on fragmentation of the same molecules via electron-impact ionization. 相似文献
11.
V. V. Afrosimov A. A. Basalaev E. A. Berezovskaya M. N. Panov O. V. Smirnov A. V. Tulub 《Technical Physics》2006,51(12):1553-1562
Fragmentation accompanying the loss of electrons by butane and isobutane (C4H10) molecules in collisions with energy H+, He2+, and Ar6+ ions of kiloelectronvolt energies is studied. The electron density functional technique is applied to C n H2n+2 alkane molecules and their respective C n H 2n+2 + ions to carry out quantum-chemical calculations of the atomic spacing, electron total energy for the initial configuration of the ionizing molecules and ions in the ground state, and atomic bond breaking energy necessary to produce different ion fragments. The fragmentation energy is correlated with the fragmentation probability. It is shown that the relative cross sections of ion fragmentation depend primarily on the related energy consumption. However, the process cross section is also strongly affected by the initial configuration of C4H10 isomer molecules, as well as by the amount of dangling and arising atomic bonds involved in the formation of each ion fragment. 相似文献
12.
S. Martin J. Bernard L. Chen A. Denis J. Désesquelles 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1998,4(1):1-6
Electron capture by Ar8+ in collisions with C60 fullerene has been investigated using coincident measurements of the number n of ejected electrons, the mass and charge of multicharged Cr+
60
recoil ions and their fragments Ci+
m and the final charge state of outgoing projectiles Ar(8-s)+ (). The number of captured electrons r is the sum of the numbers of stabilized and emitted electrons: r
=
n
+
s. The ratio n
/
s decreases by a factor three with s increasing from 1 to 7 showing that the multiply excited states populated by capture of a large number of electrons are rather
stable against auto-ionisation. Each kinetic energy spectrum of Ar+ and Ar2+ projectiles is composed of two peaks which we attribute to collisions “inside” and “outside” the C60 cage. The measured energy shift of the projectile keV is consistent with the corresponding energy loss keV in a carbon foil with an equivalent thickness. Inside collisions are characterized by a strong dissociation of recoil
ions into light monocharged fragments and by a high multiplicity of ejected electrons.
Received: 25 March 1998 / Received in final form and Accepted: 9 June 1998 相似文献
13.
V. Bernigaud B. Manil L. Maunoury J. Rangama B. A. Huber 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2009,51(1):125-130
Ionisation and ion-induced fragmentation of tetraphenyl iron (III) porphyrin chloride (FeTPPCl) molecules have been studied
after slow collisions (v∼ 0.2 a.u.) with multiply charged ions (O3+, Ar8+). Intact molecules and large fragments are observed in charge states up to q=4. For q=1, the intact molecule is the most
abundant species, in particular, when projectiles in higher charge states are used. When the internal energy of the singly
charged ion is increased by the energy transfer during the collision, the singly charged system de-excites by the emission
of a neutral Cl-atom, a free electron or possibly a negative Cl anion. The processes are observed as direct as well as delayed
processes on a μs-time scale. For q=2 to 4 the loss of the Cl-atom and some phenyl groups becomes more likely due to the lower
stability and the larger energy transfer. The charge state distribution of atomic fragments is found to be very different,
in particular, when Cq+ and Clq+ ions are compared. In the first case mainly singly charged ions are detected, whereas in the second case ions in charge states
up to q=6 are observed with high intensities. These phenomena are discussed in terms of the intramolecular charge mobility. 相似文献
14.
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
15.
W. Spies P. Glans W. Zong H. Gao G. Andler E. Justiniano M. Saito R. Schuch 《Hyperfine Interactions》1998,114(1-4):237-243
Recent advances in studies of electron-ion recombination processes at low relative energies with the electron cooler of the
heavy-ion storage ring CRYRING are shown. Through the use of an adiabatically expanded electron beam, collisions down to 10-4eV relative energies were measured with highly charged ions stored in the ring at around 15 MeV/amu energies. Examples of
recombination measurements for bare ions of D+, He2+, N7+, Ne10+ and Si14+ are presented. Further on, results of an experiment measuring laser-induced recombination (LIR) into n=3 states of deuterium with polarized laser light are shown.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
16.
17.
S. Kumari S. N. Chatterjee L. K. Jha B. N. Roy 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2011,61(2):355-363
H+ impact single and He2+ impact single and double electron
capture cross sections of magnesium atoms have been calculated in the
modified binary encounter approximation (BEA). The accurate expressions of
ion impact sDE\sigma _{\Delta {E}} (cross section for energy transfer
DE\Delta E) and Hartree-Fock momentum distributions of the target
electrons have been used throughout the calculations. On the basis of the
present work it is concluded that inner shell captures by H+ and
He2+ ions incident on magnesium atoms contribute partly to single
electron capture and partly to transfer ionization cross sections. The
calculated He2+ impact double electron capture cross sections of
magnesium are in reasonably good agreement with the experimental
observations. This indicates the success of the present theoretical approach
in study of charge transfer cross sections of atoms as indirect mechanisms do
not interfere with double electron capture processes in this case. 相似文献
18.
S. Martin L. Chen J. Bernard R. Brédy A. Salmoun 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2005,34(1-3):101-104
Highly charged C60 molecules are produced in
collisions between neutral C60 and multiply charged ions within a large
range of temperatures. Successive emission of one, two or three light
monocharged fragments referred as one-, two- and three-step processes have
been observed. The experimental mass branching ratios for the emission of
one C2n+ fragment from C606+, C605+ and
C604+ ions are compared with the theoretical values using a
statistical model. From hotter C606+ ions, branching ratios for
three-step processes have been measured and the data are in good agreement
with an estimation using the branching ratios in one-step process. 相似文献
19.
利用冷靶反冲离子动量谱仪,对低能He2+-He碰撞反应中产生的反冲靶离子和炮弹离子进行了符合测量,根据反冲靶离子的动量,研究了转移电离过程中的电荷转移机理.实验结果表明:在20—40 keV能量范围内,靶原子上的一个电子俘获到炮弹离子的基态,另一个电子直接发射到靶的连续态的直接电离及另一个电子俘获到炮弹离子的连续态的过程(ECC)是最主要的转移电离机理,且ECC过程主要发生在大碰撞参数条件下;炮弹离子俘获两个电子处在双激发态的自电离过程的贡献很小.
关键词:
冷靶反冲离子动量谱仪
转移电离机理
离子原子碰撞 相似文献