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1.
Johnsson P Mauritsson J Remetter T L'Huillier A Schafer KJ 《Physical review letters》2007,99(23):233001
A train of attosecond pulses, synchronized to an infrared (IR) laser field, is used to create a series of electron wave packets (EWPs) that are below the ionization threshold in .helium. The ionization probability is found to strongly oscillate with the delay between the IR and attosecond fields twice per IR laser cycle. Calculations that reproduce the experimental results demonstrate that this ionization control results from interference between transiently bound EWPs created by different pulses in the train. In this way, we are able to observe, for the first time, attosecond wave-packet interference in a strongly driven atomic system. 相似文献
2.
Attosecond transient absorption spectroscopy:Comparative study based on three-level modeling
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In the present paper, the time-resolved transient absorption spectroscopy of helium atoms is investigated based on the three-level modeling. The helium atoms are subjected to an extreme ultraviolet(XUV) attosecond pulse and a time-delayed infrared(IR) few-cycle laser field. The odd excited state are populated from the ground state by the XUV pulse due to the dipole selection rule, and probed by the time-delayed IR laser. The time-resolved transient absorption spectroscopy based on the different coupling mechanism demonstrate some different features, the photoabsorption spectrum based on three-level model with rotating wave approximation(RWA) cannot repeat the fast oscillation and the sideband structure which have been observed in the previous experimental investigation. The dressing effect of IR laser pulse on the ground state can contribute new interference structures in the photoabsorption spectrum. 相似文献
3.
Naumova N Sokolov I Nees J Maksimchuk A Yanovsky V Mourou G 《Physical review letters》2004,93(19):195003
Electron bunches of attosecond duration may coherently interact with laser beams. We show how p-polarized ultraintense laser pulses interacting with sharp boundaries of overdense plasmas can produce such bunches. Particle-in-cell simulations demonstrate attosecond bunch generation during pulse propagation through a thin channel or in the course of grazing incidence on a plasma layer. In the plasma, due to the self-intersection of electron trajectories, electron concentration is abruptly peaked. A group of counterstream electrons is pushed away from the plasma through nulls in the electromagnetic field, having inherited a peaked electron density distribution and forming relativistic ultrashort bunches in vacuum. 相似文献
4.
Kohler MC Ott C Raith P Heck R Schlegel I Keitel CH Pfeifer T 《Physical review letters》2010,105(20):203902
High-order harmonic generation (HHG) is investigated theoretically in the over-the-barrier ionization regime revealing the strong signature of interference between two separately ionized and separately propagating free wave packets of a single electron. The interference leads to the emission of coherent light at a photon energy corresponding to the kinetic-energy difference of the two recolliding electron quantum paths, thus complementary to the well-known classical three-step picture of HHG. As will be shown by time-frequency analysis of the emitted radiation, the process entirely dominates the coherent HHG emission after the atomic ground state has been depleted by a strong field. Moreover, it can be isolated from the continuum-bound harmonics via phase matching. 相似文献
5.
Ohmori K Katsuki H Chiba H Honda M Hagihara Y Fujiwara K Sato Y Ueda K 《Physical review letters》2006,96(9):093002
The quantum interference of two molecular wave packets has been precisely controlled in the B electronic state of the I2 molecule by using a pair of fs laser pulses whose relative phase is locked within the attosecond time scale and its real-time evolution has been observed by another fs laser pulse. It is clearly observed that the temporal evolution changes drastically as a function of the relative phase between the locked pulses, allowing us to read both amplitude and phase information stored in the wave functions of the molecular ensemble. 相似文献
6.
Johnsson P López-Martens R Kazamias S Mauritsson J Valentin C Remetter T Varjú K Gaarde MB Mairesse Y Wabnitz H Salières P Balcou P Schafer KJ L'Huillier A 《Physical review letters》2005,95(1):013001
We use a train of sub-200 attosecond extreme ultraviolet (XUV) pulses with energies just above the ionization threshold in argon to create a train of temporally localized electron wave packets. We study the energy transfer from a strong infrared (IR) laser field to the ionized electrons as a function of the delay between the XUV and IR fields. When the wave packets are born at the zero crossings of the IR field, a significant amount of energy (approximately 20 eV) is transferred from the field to the electrons. This results in dramatically enhanced above-threshold ionization in conditions where the IR field alone does not induce any significant ionization. Because both the energy and duration of the wave packets can be varied independently of the IR laser, they are valuable tools for studying and controlling strong-field processes. 相似文献
7.
Lilin Jiang Weilong Liu Yunfei Song Xing He Yang Wang Yanqiang Yang 《Applied physics. B, Lasers and optics》2014,116(2):271-277
The dynamics and spectroscopic characteristics of the ultrafast photoinduced electron transfer (ET) of Rhodamine 6G (Rh6G+) in N,N-diethylaniline (DEA) were studied using femtosecond time-resolved multiplex transient grating and transient absorption spectroscopies. The ultrafast photoinduced forward ET from DEA to the Rh6G+* cation radical excited state has a time constant of τ FET = 219–318 fs. The much slower backward ET from the neutral radical Rh6G· to DEA+ with a time constant of τ BET = 22.76–42.31 ps occurs in the inverted region. Intramolecular vibrational relaxation of the excited state takes place in τ IVR = 2.18–6.91 ps. 相似文献
8.
The attosecond pump probe, in close analogy to the standard femtosecond probing technique, has been proposed and theoretically demonstrated with its application to explore ultrafast electron motions inside atoms. We have performed realistic modeling for the full dynamics of both the femtosecond pumping and the attosecond probing processes. Our simulations have illustrated that an ultrashort oscillation period of 2.0 fs can be mapped out for a wave packet in low-lying excited states of the helium atom. This opens the prospect of a wealth of similar pump probe experiments to examine ultrafast electronic or atomic motions. 相似文献
9.
S. Bouquet J. Bergner J. Le Héricy J.P. Langeron 《Journal of Electron Spectroscopy and Related Phenomena》1982,26(3):247-257
During heating, a TiAl alloy becomes covered by elemental sulphur and chlorine which remain segregated at the surface after cooling. Auger electron spectroscopy has shown that the chlorine disappears progressively with time at room temperature, while the sulphur is not removed. Experiments have been performed which show that the disappearance of chlorine is due to electron bombardment and that chlorine is expelled only locally from a zone around, and considerably larger than, the area of beam impact. We suggest that chlorine escapes from the impact area by superficial diffusion and not by electron-stimulated desorption. The influence of various parameters, such as the properties of the electron beam and the temperature of the sample, have been studied in an attempt to explain the observed electron beam effect. 相似文献
10.
Nonlinear absorption by quantum interference in cold atoms 总被引:1,自引:0,他引:1
We report an experimental observation of third-order nonlinear absorption by quantum interference in (87)Rb atoms cooled and confined in a magneto-optic trap. A coupling laser creates electromagnetically induced transparency (EIT) in a multilevel Rb system in which the third-order nonlinear absorption is enhanced by constructive quantum interference while the linear absorption is inhibited by destructive interference. Our experiment demonstrates the EIT system proposed by Harris and Yamamoto [Phys. Rev. Lett. 81, 3611 (1998)], which absorbs two photons but not one photon in the dressed-state picture. 相似文献
11.
Attosecond photoelectron spectroscopy of electron tunneling in a dissociating hydrogen molecular ion
We demonstrate the potential of intense-field pump, attosecond probe photoelectron spectroscopy to monitor electron tunneling between the two protons during dissociative ionization of the hydrogen molecule, with attosecond temporal and Angstrom-scale spatial resolution. 相似文献
12.
Caillat J Maquet A Haessler S Fabre B Ruchon T Salières P Mairesse Y Taïeb R 《Physical review letters》2011,106(9):093002
We have simulated two-color photoionization of N(2) by solving the time-dependent Schr?dinger equation with a simple model accounting for the correlated vibronic dynamics of the molecule and of the ion N(2)(+). Our results, in very good agreement with recent experiments [Haessler et al., Phys. Rev. A 80, 011404 (2009)], show how a resonance embedded in the molecular continuum dramatically affects the phases of the two-photon transition amplitudes. In addition, we introduce a formal relation between these measurable phases and the photoelectron release time, opening the way to attosecond time-resolved measurements, equivalent to double-slit experiments in the time domain. 相似文献
13.
Wing-Cheung Tam C.E. Brion 《Journal of Electron Spectroscopy and Related Phenomena》1974,3(4):281-288
The electron energy loss spectrum of HCN has been determined in the energy region 8–13.6 eV at impact energies of 100, 50 and 30 eV. It is shown that energy loss spectra of HCN at intermediate impact energies can be satisfactorily analysed unlike the diffuse unassigned optical absorption spectra that have previously been reported. Rydberg series have been assigned using term values and quantum defects together with ionization potentials obtained by photoelectron spectroscopy. 相似文献
14.
Johnson SL Heimann PA Lindenberg AM Jeschke HO Garcia ME Chang Z Lee RW Rehr JJ Falcone RW 《Physical review letters》2003,91(15):157403
Time-resolved x-ray spectroscopy at the Si L edges is used to probe the electronic structure of an amorphous Si foil as it melts following absorption of an ultrafast laser pulse. Picosecond temporal resolution allows observation of the transient liquid phase before vaporization and before the liquid breaks up into droplets. The melting causes changes in the spectrum that match predictions of molecular dynamics and ab initio x-ray absorption codes. 相似文献
15.
Faraci G Pennisi AR Balerna A Pattyn H Koops GE Zhang G 《Physical review letters》2001,86(16):3566-3569
Cobalt was introduced into a silver matrix by ion implantation and observed by extended x-ray absorption fine structure (EXAFS) spectroscopy. In the range 0.10--0.70 at. % evidence of Co dimers dispersed in the matrix was found. The dimers are somewhat contracted with respect to the bulk Co nearest neighbor distance and distributed in a chainlike configuration with each dimer at 90 degrees from each other along opposite square faces of the Ag fcc lattice. 相似文献
16.
Pairs of pulses from an incoherent source are used to investigate the time-resolved four-wave mixing response of atomic rubidium when a two-photon resonance is involved in the nonlinear process. By varying the relative polarization of the pulse pairs, we are able to select the quantum pathways and clearly distinguish optical and quantum interferences. 相似文献
17.
By means of time-resolved electron crystallography, we report direct observation of the structural dynamics of graphite, providing new insights into the processes involving coherent lattice motions and ultrafast graphene ablation. When graphite is excited by an ultrashort laser pulse, the excited carriers reach their equilibrium in less then one picosecond by transferring heat to a subset of strongly coupled optical phonons. The time-resolved diffraction data show that on such a time scale the crystal undergoes a contraction whose velocity depends on the excitation fluence. The contraction is followed by a large expansion which, at sufficiently high fluence, leads to the ablation of entire graphene layers, as recently predicted theoretically. 相似文献
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20.
A. Schabert R. Keil P. E. Toschek 《Applied Physics A: Materials Science & Processing》1975,6(2):181-184
Cross-saturated absorption at the neon line 2s
2–2p
4 caused by the saturating line 3s
2–2p
4 has been applied to the observation of the dynamic Stark effect by 1) power broadening, due to triple-quantum and higher
multiple-quantum transitions, of the light shift contribution to the susceptibility, and 2) a direct splitting in the electronic
Raman-Stokes contribution which occurs because of the partial compensation of the Doppler broadening.
Work supported by the “Deutsche Forschungsgemeinschaft”. 相似文献