共查询到20条相似文献,搜索用时 15 毫秒
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Frasinski LJ Plumridge J Posthumus JH Codling K Taday PF Divall EJ Langley AJ 《Physical review letters》2001,86(12):2541-2544
The multiphoton ionization of H2 has been studied using laser pulses of 266 nm wavelength, 250 fs duration, and 5x10(13) W/cm(2) peak intensity. Dissociation of H2(+) via one-photon absorption proceeds through two channels with markedly different proton angular distributions. The lower-energy channel (2.6 eV kinetic energy release) is produced in the bond softening mechanism, which generates parallel alignment. The higher-energy channel (3.5 eV) originates from population trapping in a light-induced bound state, where bond hardening generates orthogonal, counterintuitive alignment. 相似文献
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Aihong Tong Yueming Zhou Cheng Huang Qing Liao Peixiang Lu 《Optics Communications》2011,284(10-11):2505-2508
Using three-dimensional classical ensembles, we have investigated the enhancement of double ionization of perpendicularly aligned H2 molecules by a 800 nm laser pulse with intensity ranging from 1 × 1014 W/cm2 to 6 × 1014 W/cm2. The simulated results show that double ionization probability of H2 strongly depends on R and reaches a maximum at an intensity independent critical distance RC ≈ 5 a.u. Furthermore, the enhancement of double ionization is more pronounced in the cases of weaker or stronger fields. These results, a well indication of the influence of molecular structures and laser–molecule interactions on double ionization of diatomic molecules, are analyzed in detail and qualitatively explained based on the field-induced barrier suppression model and back analysis. 相似文献
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Ergler T Rudenko A Feuerstein B Zrost K Schröter CD Moshammer R Ullrich J 《Physical review letters》2005,95(9):093001
We report on the experimental realization of time-resolved coincident Coulomb explosion imaging of H2 fragmentation in 10(14) W/cm(2) laser fields. Combining a high-resolution "reaction microscope" and a fs pump-probe setup, we map the motion of wave packets dissociating via one- or two-photon channels, respectively, and observe a new region of enhanced ionization. The long-term interferometric stability of our system allows us to extend pump-probe experiments into the region of overlapping pulses, which offers new possibilities for the manipulation of ultrafast molecular fragmentation dynamics. 相似文献
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The Coulomb explosion dynamics of H2S, H2S3+-->H+ +S+ + H+, in ultrashort intense laser fields (12 fs, approximately 2 x 10(14) W/cm2) is studied by the coincidence momentum imaging of the three fragment ions. Different electronic and nuclear responses are identified depending on the direction of laser polarization epsilon in the molecular frame. The dependence can be interpreted in terms of the electronic and bonding characters of charge transfer states of H2S coupled to the electronic ground state. 相似文献
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A. Wadehra B. M. Deb 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2006,39(1):141-155
Under interaction with a high-intensity laser field, the real-time
femtosecond dynamics of the electron density in the H2
molecule has been studied quantum mechanically. For this purpose, a
time-dependent generalized nonlinear Schr?dinger equation of motion,
developed earlier in our laboratory by combining density functional theory
and quantum fluid dynamics in real space, is solved numerically at the
equilibrium internuclear distance of the molecule. By employing various
time-dependent calculated properties as probes, information and insight are
obtained about the phenomena of excitation, ionization, bond-softening,
dipole formation and high-harmonics generation. The present approach goes
beyond the linear response formalism. 相似文献
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Hikosaka Y Fushitani M Matsuda A Tseng CM Hishikawa A Shigemasa E Nagasono M Tono K Togashi T Ohashi H Kimura H Senba Y Yabashi M Ishikawa T 《Physical review letters》2010,105(13):133001
Photoelectron spectroscopy has been performed to study the multiphoton double ionization of Ar in an intense extreme ultraviolet laser field (hν ~ 21 eV, ~ 5 TW/cm2), by using a free electron laser (FEL). Three distinct peaks identified in the observed photoelectron spectra clearly show that the double ionization proceeds sequentially via the formation of Ar(+): Ar+hν→Ar (+) + e? and Ar2(+) + 2hν→Ar(+) + e?. Shot-by-shot recording of the photoelectron spectra allows simultaneous monitoring of FEL spectrum and the multiphoton process for each FEL pulse, revealing that the two-photon ionization from Ar(+) is significantly enhanced by intermediate resonances in Ar(+). 相似文献
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选用两个模型势,利用强场近似方法研究了H-离子在线性极化强激光场中二维光电子动量谱中次外层后重散射环.研究结果表明:两个模型势中的极化势对二维光电子动量谱的影响很小;随着激光强度的增加,二维光电子动量谱中出现后重散射环的数目变多,沿着次外层后重散射环的光电子的角分布波动性变小,能够通过多项式拟合的方法从二维光电子动量谱中次外层后重散射环获得精确的电子与H原子的弹性散射截面,特别适用于激光强度较小的情况. 相似文献
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Two-dimensional (2D) electron momentum distributions and energy spectra of a hydrogen in an intense laser field are calculated by solving the time-dependent Schrödinger equation combined with the window-operator technique. Compared with the standard projection technique, the window-operator technique has the advantage that the continuum states of atoms can be avoided in the calculation. We show that the 2D electron momentum distributions and the energy spectra from those two techniques accord quite well with each other if an appropriate energy width is used in the window operator. 相似文献
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A simple model is developed that quantitatively describes intense interactions of a vacuum ultraviolet (VUV) laser pulse with a xenon cluster. We find good agreement with a recent experiment [Nature (London) 420, 482 (2002)]]. In particular, the large number of VUV photons absorbed per atom, at intensities significantly below 10(16) W/cm(2), is now understood. 相似文献
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A second plateau in the harmonic spectra of laser-driven two-electron atoms is observed both in the numerical solution of a low-dimensional model helium atom and using an extended strong field approximation. It is shown that the harmonics well beyond the usual cutoff are due to the simultaneous recombination of the two electrons, which were emitted during different, previous half-cycles. The new cutoff is explained in terms of classical trajectories. Classical predictions and the time-frequency analysis of the ab initio quantum results are in excellent agreement. The mechanism corresponds to the inverse single photon double ionization process in the presence of a (low frequency) laser field. 相似文献
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We present a photodissociation experiment on H+2 with ultrashort laser pulses ( >/=130 fs) at peak intensities of =1.5x10(14) W/cm(2). Since in an ion beam setup H+2 is produced in a discharge source spatially separated from the light interaction zone interference with neutral H2 can be excluded in the interpretation. As the beam setup allows a high energy resolution of photofragments, effects predicted by the light induced potential theory can be tested in detail. The one-photon trapping effect was detected and the angular distributions of fragments from single vibrational levels were measured. Fragment energy spectra deviate strongly from those obtained by experiments on H2. 相似文献
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We investigate the ionization of icosahedral fullerenes (C20, C60, C80, and C180) in an intense laser pulse using the S-matrix theory. The results obtained are in excellent agreement with the recent observations of unexpectedly high saturation intensities of the Buckminster fullerene and its multiply charged ions. Our analysis strongly suggests that the related phenomenon of suppressed ionization of these complex fullerenes is due to the finite cage size and the "multislit" interference effect between partial waves emitted from the different nuclei rather than to a dynamical multielectron polarization effect. 相似文献
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Accurate and efficient grid based techniques for the solution of the time-dependent Schrödinger equation for few-electron diatomic molecules irradiated by intense, ultrashort laser pulses are described. These are based on hybrid finite-difference, Lagrange mesh techniques. The methods are applied in three scenarios, namely H2
+ with fixed internuclear separation, H2
+ with vibrating nuclei and H2 with fixed internuclear separation and illustrative results presented.Received: 19 November 2002, Published online: 24 April 2003PACS:
02.60.Cb Numerical simulation; solution of equations - 02.70.Bf Finite-difference methods - 33.80.Rv Multiphoton ionization and excitation to highly excited states (e.g., Rydberg states) - 33.80.-b Photon interactions with molecules 相似文献