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1.
The multiply charged ions of C q + (q ≤ 4), O q + (q ≤ 6) were produced when a furan cluster beam interacted with nanosecond 1064 and 532 nm lasers at intensities of 1010–1012 W/cm2. It is shown that O6+ and C4+ ions were the dominant multiply charged species at 1064 nm, while C2+, C3+, O2+, O3+ ions were the main multiply charged species at 532 nm. By varying the electric field in the extraction region of the time of flight mass spectrometer (TOFMS), two types of ions were extracted, one of which had large kinetic energy and narrow space distribution, and the other had small kinetic energy and broad space distribution. The formation channels for He-like ions of C4+ and O6+ are discussed. 相似文献
2.
纳秒激光与团簇相互作用产生高价离子逐渐成为分子物理界的热点之一, 为了深入研究团簇电离的本质, 本文以分子结构相似、元素组成相同的苯、环己烯和环己烷的分子团簇为对象, 利用飞行时间质谱研究了其与5 ns的532 nm激光相互作用时电离产物的价态和强度分布. 结果表明: 这三种化合物多光子电离效率苯>环己烯>环己烷, 但其高价离子的价态和比值苯是最低的, 环己烷的碳离子最高价态为4价, C3+和C2+的比值为1.1; 环己烯电离产物C3+和C2+ 的比值降低为0.6; 苯团簇的最高价态只有3价, C3+和C2+的比值约为0.4. 引起这种现象的原因可以归结于高的多光子电离效率会导致团簇多位点的电离, 引起团簇在电子加热到发生碰撞电离之前发生解离, 减小了团簇的尺寸, 进而减少了离子发生碰撞电离产生高价离子的反应时间, 最终阻碍了高价态离子的产生. 相似文献
3.
S. N. Morozov 《Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques》2012,6(4):660-663
The spectra of secondary ion emission under the bombardment of a B-doped Si target by multiply charged Si q+ ions (q = 1?C5) have been studied in the energy range of 1 to 10 keV per unit of charge. A multifold increase in the yield of secondary cluster Sk n + ions, multiply charged Si q/+ ion (q = 1?C3), and H+, C+, B+, Si2N+, Si2O+ is observed as the charge of the multiply charged ions increases. The increase in the yield of secondary ions with increasing charge of the multiply charged-ion charge is most significant for ions with relatively high ionization potentials. 相似文献
4.
利用脉宽为25ns的脉冲Nd: YAG 532 nm的激光,在8×1010W/cm2的强度下,用飞行时间质谱对CS2的激光电离过程进行了研究.观察到了较强的C2+和S2+高价离子信号,这些高价离子C2+,S2+的最可几平动能高达144 eV,112 eV.不同进样方式,激光延迟以及束源压力的实验结果表明,这些高价离子可能来源于CS2团簇的库仑爆炸过程.多光子电离引发,逆韧致吸收加热-电子碰撞电离模型可能是高价离子产生的机理.
关键词:
2')" href="#">CS2
团簇
高价离子
激光电离 相似文献
5.
用5ns,1064nm的脉冲Nd:YAG激光,研究了乙醚团簇与纳秒激光的相互作用.在1011 W/cm2量级光强下,观察到价电子完全剥离的O6+,C4+,且这些高价离子的强度比值基本不随激光能量而变化.用阻滞电压方法测量了电离过程中溢出电子能量分布,在最大激光能量4.0×1011 W/cm2,溢出电子的平均能量为56eV,最大能量为102eV.实验结果支持了高价离子产生的“多
关键词:
高价离子
电子能量
纳秒激光
乙醚团簇 相似文献
6.
B. A. Zon A. S. Kornev E. B. Tulenko 《Journal of Experimental and Theoretical Physics》2010,111(6):921-935
Some of the many-body effects in the formation of multiply charged ions in a laser field have been taken into account: inelastic
tunneling, collective tunneling, and magnetic moment projection relaxation of the atomic core. Strong fields with an intensity
exceeding 1017 W cm−2 are considered when the magnetic component of the laser field acts on the free motion of a photoelectron; therefore, the
formation of multiply charged ions through rescattering becomes unlikely. Numerical calculations have been performed for Ar9+ … Ar13+, Kr19+ … Kr23+, Rb10+, and Rb11+ ions. A significant contribution of collective tunneling, which was not observed in weaker fields investigated previously,
has been revealed. Allowance for collective tunneling is shown to reduce the intensity leading to saturation by more than
10%. In this case, the yield of multiply charged Rb ions changes by an order of magnitude, while the yield of multiply charged
Ar and Kr ions changes by more than a factor of 2. Comparison with experimental data on the formation of argon ions under
the action of a linearly polarized laser pulse is made. 相似文献
7.
A theory of thermonuclear fusion caused by the irradiation of deuterium-iodide clusters with the field of a superatomic femtosecond laser pulse is developed. It is based on considering the process in which the sequential above-barrier multiple internal ionization of atomic ions within a cluster is accompanied by external field ionization. The theory is illustrated by taking the example of a cluster that is formed by 106 molecules of deuterium iodide and which is irradiated with a laser pulse of duration 50 fs and intensity 2×1018 W/cm2 at the peak. This case is dominated by I26+ atomic ions. The yield of neutrons from thermonuclear fusion in a deuteron-deuteron collision upon the passage of a laser pulse is calculated. The result is 105 neutrons per laser pulse. The mean kinetic energy of deuterons is estimated at 50 keV. Owing to induced inverse bremsstrahlung in scattering on multiply charged atomic ions, the electron temperature increases up to 28 keV. The role of the Mie resonance in the heating of the electron component is discussed. 相似文献
8.
利用脉宽为25 ns的脉冲Nd: YAG 532 nm的激光,在1010—1011 W/cm2的强度下,用飞行时间质谱对丙酮团簇的激光电离过程进行了研究. 观察到了较强的Oq+(q=2—4)和Cq+(q=1—4)高价离子信号,这些高价离子 C4+,C3+,C2+,O4+,O3+,O2+的最大概然平动能分别为240 eV,70 eV,30 eV,90 eV,80 eV,40 eV. 高价离子的强度和平动能随激光强度的增大而增大. 我们提出一个多光子电离引发,逆韧致吸收加热-电子碰撞电离模型来解释高价离子的产生.
关键词:
丙酮
团簇
库仑爆炸
高价离子 相似文献
9.
Here, we report the kinetic energy distributions (KEDs) of the fragment ions produced from multiply ionized ethane (C2H6) molecules in single electron capture collisions with 1.2 MeV C2+. To systematically investigate the fragmentation dynamics, the KEDs were obtained as functions of the charge state of the intermediate C2H6r+* ions r transiently generated prior to fragmentation. r was determined from coincidence measurement of the fragment ions and the number of emitted electrons. The KEDs are drastically different depending on the number of broken C–H bonds. The underlying causes are explained by the variation of the relative contributions of the multiply ionized states and preferential fragmentation pathways. For instance, CHn+ fragment ions with smaller n exhibit lower KEs because they are likely to be correlated with H+ emission, which carries away a large portion of the KE release. In addition, we report the KEDs of H3+ produced from doubly and triply charged states. 相似文献
10.
V. Berardi M. Armenante R. Bruzzese F. Esposito S. Solimeno N. Spinelli S. Bakhramov 《Il Nuovo Cimento D》1991,13(4):423-433
The intensity dependence of the multiphoton ionization spectra of Xe atoms has been investigated with an improved accuracy
and well-controlled laser parameters. In particular, we have examined the ionization rates for X3+, X2−, X+ as functions of the laser intensity and the pressure in the target chamber. The apparatus used for these measurements is
characterized by a high-energy resolution (better than 200 meV) and a completely digital acquisition system. The time-of-flight
spectra clearly show the contributions of the different isotopes present in Xe gas. The laser pulses have been characterized
with great accuracy by monitoring the energy, pulse width and divergence shot by shot. The ionization rates of the different
ions have been used for testing the basic assumption of the Geltman theory of multiple ionization based on the single electron
ionization model. We have found that for the small intensity range investigated the quantity (dXe
+/dI)·(dXe
3+/dI)/(dXe
2+/dI)2 appears to be quite close to the value 0.5 predicted by this model. 相似文献
11.
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
12.
J. Krása L. Torrisi A. Picciotto D. Margarone S. Gammino L. Láska 《辐射效应与固体损伤》2013,168(10-12):609-619
The emission of ions from laser-produced carbon plasmas is investigated by a deconvolution of ion collector signals. The deconvolution is based on the use of Kelly and Dreyfus function expressing the time-resolved ion current to recover hidden peaks in an ion collector signal. The parameters of recovered C q+ (1?≤?q?≤?6) currents make possible the quantification of properties of laser-produced plasmas. The drift and peak velocities of C q+ ions, the abundance of ions and the plasma temperature are presented in the dependence on focused laser beam energy. The carbon plasma was generated employing either single 9-ns pulses of second harmonics (532 nm) of Nd:YAG laser or pulses repeated at a stable repetition rate of 30 Hz. 相似文献
13.
Multi-reference configuration-interaction calculations on multiply charged ions of carbon monosulfide
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The potential energy curves for neutrals and multiply charged ions of carbon monosulfide are computed with highly correlated multi-reference configuration interaction wavefunctions.The correlations of inner-shell electrons with the scalar relativistic effects are included in the present computations.The spectroscopic constants,dissociation energies,ionization energies for ground and low-lying excited states together with corresponding electronic configurations of ions are obtained,and a good agreement between the present work and existing experiments is found.No theoretical evidence is found for the adiabatically stable CSq+(q>2) ions according to the present ab initio calculations.The calculated values for 1st-6th ionization energies are 11.25,32.66,64.82,106.25,159.75,and 224.64 eV,respectively.The kinetic energy release data of fragments are provided by the present work for further experimental comparisons. 相似文献
14.
A systematic theoretical study of laser-irradiated targets made of material with increasing atomic number has been performed.
The formation of energetic light ions resulting from the interaction of an intense ultrashort pulse laser with thin planar
targets is investigated theoretically with a two-dimensional relativistic electromagnetic particle-in-cell model. A common
parameter, the areal electron density of the foil, can be used to describe qualitatively targets made of different material.
By varying either the laser intensity or the target thickness we observe a gradual transition of various ion acceleration
mechanisms from one into another. Light ions, such as H+, Li3+, C6+, and Al13+, can be accelerated to GeV energies with existing laser systems at a laser fluence of 10–20 J/μm2. 相似文献
15.
《Comptes Rendus Physique》2002,3(3):353-364
We review progress made in understanding Coulomb explosion of multiply charged atomic clusters. Their collision with highly charged atomic ions leads to clusters in charge states as high as z=10 with little vibrational excess energy; these systems approach the Rayleigh limit. Phase transitions become evident at higher excess energies. Numerous studies have been devoted to Cz+60, like collisions with surfaces, multi-coincidence fragmentation analysis and gas-phase reactions. Stability and decay of highly charged micrometer-sized droplets and of metal di- and trianions have been monitored in ion traps. Excitation by femtosecond laser pulses allows to unravel properties of highly charged transient cluster ions. To cite this article: O. Echt et al., C. R. Physique 3 (2002) 353–364. 相似文献
16.
M.A. Lebeault J. Viallon J. Chevaleyre C. Ellert D. Normand M. Schmidt O. Sublemontier C. Guet B. Huber 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,20(2):233-242
We exposed small size-controlled lead clusters with a few hundreds of atoms to laser pulses with peak intensities up to 1015 W cm-2 and durations between 60 fs to 2.5 ps. We measured kinetic energies and ionic charge of fragments as a function of the laser
intensity and pulse duration. Highly charged Pbn+ ions up to n = 26 have been detected presenting kinetic energies up to 15 keV. For comparison with our experimental results, we have performed
simulations of the laser coupling with a cluster-sized lead nanoplasma using a qualitative model that was initially proposed
by Ditmire and co-workers at LLNL for the case of rare gas clusters. From these simulations we conclude that two mechanisms
are responsible for the explosion dynamics of small lead clusters. As already observed for large rare gas clusters (n = 106), fragments with charge states below +10 are driven by Coulomb forces, whereas the higher charged fragments are accelerated
by hydrodynamic forces. The latter mechanism is a direct consequence of the strong laser heating of the electron cloud in
the nanoplasma arising from a plasmon-like resonance occurring at n
e = 3n
c. In order to obtain an optimized laser-nanoplasma coupling, our results suggest that the plasma resonance should occur at
the peak intensity of the laser pulse. Due to inertial effects, even for such small-sized clusters, the observed optimum pulse
duration is in the order of 1 ps which is in good agreement with our theoretical results.
Received 18 March 2002 Published online 19 July 2002 相似文献
17.
Titanium clusters are produced by laser vaporization of a metal wire in a helium gas pulse, stored in a Penning trap, size
selected and transformed into multiply charged anions by electron attachment. Both doubly and triply charged titanium clusters
are observed. For the first observation of photodetachment of electrons from metal cluster dianions, Ti
55
2-
clusters are selected and excited by a laser pulse, which leads to the emission of an excess electron: Ti
55
2-
→ e− + Ti
55
-
.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
18.
19.
J. Lecointre H. Cherkani-Hassani S. Cherkani-Hassani D. S. Belic J. J. Jureta P. Defrance 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2010,60(2):331-345
Absolute cross sections for electron-impact single ionization, dissociative
excitation and dissociative ionization of the ethynyl radical ion
(C2D+)^+) have been measured for electron energies ranging from the
corresponding reaction thresholds to 2.5 keV. The animated crossed
electron-ion beam experiment is used and results have been obtained for the
production of C2D2+, C2+, C2+_2^+ , CD+, C+ and
D+. The maximum of the cross section for single ionization is found to
be (2.01 ± 0.02) × 10-17 cm2, at the incident electron
energy of 105 eV. Absolute total cross sections for the various singly
charged fragments production are observed to decrease by a factor of almost
three, from the largest cross-section measured for C+, over C2+_2^+
and CD+ down to that of D+. The maxima of the cross sections are
obtained to be (14.5 ± 0.5) × 10-17 cm2 for C2+_2^+,
(12.1 ± 0.1) × 10-17 cm2 for CD+, (27.7 ±
0.2) × 10-17 cm2 for C+ and (11.1 ± 0.8) × 10-17 cm2 for D+.
The smallest cross section is measured to
be (1.50 ± 0.04) × 10-18 cm2 for the production of the
doubly charged ion C2+. Individual contributions for dissociative
excitation and dissociative ionization are determined for each
singly-charged product. The cross sections are presented in closed analytic
forms convenient for implementation in plasma simulation codes. Kinetic
energy release distributions of dissociation fragments are seen to extend
from 0 to 6 eV for the heaviest fragment C2+_2^+, up to 11.0 eV for
CD+, 14.2 eV for C+ and 11.2 eV for D+ products. 相似文献
20.
研究了高电荷态离子129Xeq+(q=25,26,27)入射金属Mo表面产生的特征X射线谱.实验结果表明,在束流强度小于120nA条件下,高电荷态离子129Xeq+可以激发Mo的L壳层特征X射线谱.单离子X射线相对产额可达10-8量级,特征X射线的相对产额随入射离子的动能和电荷态(势能)的增加而增加.通过Mo原子的Lα1特征X射线谱,利用Heisenberg不确定关系对Mo原子的第M能级寿命进行了估算. 相似文献