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31.
A. Flettner J. König M.B. Mason T. Pfeifer U. Weichmann R. Düren G. Gerber 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,21(1):115-119
High harmonic generation is compared in the dependence on the ellipticity of the fundamental laser radiation for an atomic
and a molecular system. In particular argon and nitrogen are compared employing molecular beams and intense ( 3×1014 W/cm2) and ultrashort (80 fs) 800 nm laser pulses. It turns out that for all the harmonics under investigation (H5, H13 and H21)
the harmonic yield decreases slower with the ellipticity for the molecule than for the atom. This indicates differences in
atomic and molecular high harmonic generation.
Received 24 April 2002 Published online 24 September 2002 相似文献
32.
A classical microcanonical 1+1-dimensional model is used to investigate the ion momentum distributions in nonsequential double ionization with linearly polarized few-cycle pulses. We find that the ion momentum distribution has a strong dependence on the carrier-envelope phase of the few-cycle pulse, which is consistent with the experimental results qualitatively. Back analysis shows that the ionization probability of the first electron at different phases and its returning kinetic energy play the main role on the ion momentum distributions. 相似文献
33.
Measurements of multiple rotational lines in the (1, 0) band of the A2Πi − X2Σ+ “red” system of the cyanogen radical (CN) at sub-Doppler resolution are reported. The CN radical was produced by 193 nm photodissociation of NCCN (ethane dinitrile) and detected with a Ti:sapphire ring laser operating near 10 900 cm−1. The sample was exposed to a weak, frequency-modulated probe beam and a strong, counterpropagating bleach laser beam. Demodulated probe laser signals display absorption and dispersion features derived from Doppler-free saturation of the hyperfine components as the laser scans across the central region of a Doppler-broadened rotational line spectrum. Hyperfine-resolved transition frequencies were combined with known ground-state X2Σ hyperfine term values to determine A2Π state hyperfine term values, which were analyzed in terms of an effective Hamiltonian for the A2Π state. All the expected hyperfine and 14N quadrupolar parameters were determined and their values analyzed in terms of a simple molecular orbital picture of the bonding in the radical. Higher sensitivity obtained with 400 kHz amplitude modulation of the bleach laser and additional phase-sensitive detection allowed hyperfine splittings in some rotational lines of 13C14N to be observed in natural abundance. Excited state hyperfine splittings were determined for a selection of rotational states, but not enough to determine the 13C hyperfine parameters. 相似文献
34.
T.R. Hovhannisyan A.G. Markossian G.F. Mkrtchian 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,20(1):17-25
On the base of relativistic generalized eikonal approximation wave function the multiphoton cross-sections of a Dirac particle
bremsstrahlung on an arbitrary electrostatic potential and strong laser radiation field are presented. In the limit of the
Born approximation the ultimate analytical formulas for arbitrary polarization of electromagnetic wave have been obtained
and numerically analyzed.
Received 5 April 2001 / Received in final form 18 March 2002 Published online 28 June 2002 相似文献
35.
A. Flettner J. Günther M.B. Mason U. Weichmann R. Düren G. Gerber 《Applied physics. B, Lasers and optics》2001,73(2):129-132
High harmonic generation at 1 kHz repetition rate is reported. A piezoelectric pulsed valve together with a femtosecond Ti:Sapphire
laser both operating at 1 kHz are employed to generate high harmonic radiation in xenon and argon. The characteristics of
the valve have been analyzed by using a fast ion gauge and a time-of-flight mass-spectrometer.
Received: 28 May 2001 / Revised version: 29 June 2001 / Published online: 18 July 2001 相似文献
36.
S.-M. Li Z.-J. Chen Q.-Q. Wang Z.-F. Zhou 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1999,7(1):39-44
The laser-assisted radiative capture between a positron and an antiproton is studied in detail. The theoretical results show
that the cross-section for antihydrogen formation is significantly reduced with the application of a laser background. This
effect is most marked when the laser polarization is parallelto the incident direction.
Received: 13 November 1998 / Received in final form: 16 March 1999 相似文献
37.
We show that two appropriate realizations of the su(4) algebra allow the construction of all electronic operators needed for the study of vibronic and rovibronic interactions in a G′ electronic state. In each case a full bosonic realization is made and all matrix elements are calculated. Illustrations of our formalism and comparisons with previous approaches are made in the case of ν5(F2g) and ν3(F1u) modes. 相似文献
38.
A. Godone F. Levi S. Micalizio J. Vanier 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,18(1):5-13
An analysis of the phenomenon of coherent population trapping as observed by means of the dark state in the case of optically
thick vapors in alkali metal atoms is presented. Very different behaviors are predicted for the observation of the dark state
in the fluorescence and transmission spectra of the same atomic sample when the optical length is not negligible. Among other
effects, the dark line observed in the fluorescence signal may look inverted appearing as a bright line, while in the transmission
signal a narrowing of the line width resonance line is observed for an increase of the atomic density. In the pure three-level
scheme a subnatural width is predicted. These effects, related to the electromagnetically induced transparency phenomenon,
are readily observed in experiments, which are found to be in excellent agreement with the theory developed.
Received 28 March 2001 and Received in final form 3 October 2001 相似文献
39.
Electron-Helium Scattering in a Bichromatic Laser Field in the Second-Order Born Approximation 下载免费PDF全文
The elastic scattering of electrons in atomic helium assisted by a bichromatic laser field is investigated in the second order Born approximation. The target atom is approximated by a simple screening potential. The dependence of the differential cross section on the relative phase between the two laser components is calculated, and compared with the recent results of first order Born approximation [Sun J F, Liang M C and Zhu Z L 2007 Chin. Phys. Lett. 24 2572]. 相似文献
40.
An optimum scheme is proposed to generate a strong entangled photon-pair light source by combining two incident laser lights. Such entangled photon source should have various potential applications in many fields such as quantum metrology, quantum information, and quantum lithography, etc. 相似文献