Above-threshold ionization of Mg by linearly and circularly polarized laser fields: Origin of the subpeaks in the photoelectron energy spectra

Nakajima, Takashi; Buică, Gabriela

doi:10.1103/physreva.74.023411

Cited by 20 publications

(21 citation statements)

References 26 publications

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“…In this case γ > 2I p / √ F for all the data points. Below saturation, the intensity dependence of the data is ∼ I 3 , as predicted by perturbation theory and consistent with the TDSE results in [51]. However, the PPT calculations (green dashed line in Fig.…”

Section: Linear Vs Circular Polarizationsupporting

confidence: 88%

Experimental investigation of strong-field-ionization theories for laser fields from visible to midinfrared frequencies

Lai

Szafruga

et al. 2017

Phys. Rev. A

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Strong field ionization yield versus intensity is investigated for various atomic targets (Ne, Ar, Kr, Xe, Na, K, Zn and Mg) and light polarization from visible to mid-infrared (0.4-4µm), from multiphoton to tunneling regimes. The experimental findings (normalized yield vs intensity, ratio of circular to linear polarization and saturation intensities) are compared to the theoretical models of Perelomov-Popov-Terent'ev (PPT) and Ammosov-Delone-Krainov (ADK). While PPT is generally satisfactory, ADK validity is found, as expected, to be much more limited.

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Section: Linear Vs Circular Polarizationsupporting

confidence: 88%

Experimental investigation of strong-field-ionization theories for laser fields from visible to midinfrared frequencies

Lai

Szafruga

et al. 2017

Phys. Rev. A

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“…Simultaneously, their polarizabilities are high and substantially different from those of the corresponding ions. We perform our simulations for Mg since multiphoton ionization of this atom has already attracted attention in experiment [79][80][81][82][83] and theory [84][85][86][87][88]. For Mg, I p = 0.28 a.u., α N = 71.33 a.u., and α I = 35.00 a.u., and at the wavelength of 800 nm, our simulation technique is applicable at the intensities of 2.35 × 10 13 −1.0 × 10 14 W/cm 2 , for which the Keldysh parameter is γ = 2.0 − 1.0.…”

Section: B Momentum Distributions For λ = 1600 and λ = 800 Nm: Diffementioning

confidence: 99%

Ionization in elliptically polarized pulses: Multielectron polarization effects and asymmetry of photoelectron momentum distributions

2012

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In the tunneling regime we present a semiclassical model of above-threshold ionization with inclusion of the Stark shift of the initial state, the Coulomb potential, and a polarization induced dipole potential. The model is used for the investigation of the photoelectron momentum distributions in close to circularly polarized light, and it is validated by comparison with ab initio results and experiments. The momentum distributions are shown to be highly sensitive to the tunneling exit point, the Coulomb force, and the dipole potential from the induced dipole in the atomic core. This multielectron potential affects both the exit point and the dynamics, as illustrated by calculations on Ar and Mg. Analytical estimates for the position of the maximum in the photoelectron distribution are presented, and the model is compared with other semiclassical approaches.

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“…This is a plausible answer, since the temporal evolution of those states can depend on the magnitude and the sign of the laser-chirp. To confirm this, we have again carried out numerical calculations without any excited bound states during the time-propagation of wavefunction [2,3]. The result is presented in Fig.…”

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confidence: 64%

Chirp-Dependent Above-Threshold Ionization

Nakajima

2007

2007 Conference on Lasers and Electro-Optics (CLEO)

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By solving the three-dimensional Schrödinger equation for the sodium and hydrogen atoms we demonstrate that the above-threshold ionization spectra strongly depend on the chirprates of fs laser pulses. 2007 Optical Society of America OCIS codes: (190.4180) Multiphoton processes; (320.7110) Ultrafast nonlinear optics Above-threshold ionization (ATI) is a process in which atoms in intense laser field absorb more than the minimum number of photons required for ionization. Since the fist experimental discovery of ATI by Agostini et al. in 1979 [1], ATI has been one of the important subjects in ultrafast laser-atom interactions, and now it is considered to be well-understood. In most experimental/theoretical studies, however, transform-limited pulses have been assumed. The question we would like to address in this paper is whether and how much ATI spectra would change when chirped laser pulses are used instead. To our knowledge, there are no detailed studies in the literature on ATI with chirped pulses. Naively the use of chirped pulses does not seem to change the ATI spectra compared with transform-limited pulses, provided the same peak intensities and the spectral widths of laser pulses.In this paper, we theoretically show that the ATI spectra strongly depend on the chirp-rates of fs laser pulses. For that sake, we have numerically solved the time-dependent Schrödinger equation for fs pulses with different linear chirp-rates but with the same spectral bandwidth. Before the detailed numerical study, we have first ensured that the vector potential we have employed for the time-dependent calculations produces the identical spectral bandwidth for arbitrary linear chirp-rates. Although the mathematical form of our vector potential clearly shows the property of the same spectral bandwidth for arbitrary linear chirp-rates, we have also numerically checked it by calculating the photoelectron spectra upon single-photon ionization of Na by the 200 nm pulse. After that, we move on to the detailed calculations to investigate the effects of linear chirp-rates. Figure 1 presents representative results for the Na atom. The laser parameters we have chosen are TL =13 fs (FWHM for the field) pulse duration with a Gaussian temporal envelope, central wavelength of 800 nm, and the peak intensity of 10 12 W/cm 2 for the transformlimited pulses. For chirped pulses, we have chosen the pulse duration to be 2 TL (i.e., = ± 3) and 4 TL (i.e., = ± 15) with positive as well as negative linear chirp-rates. It is clear that the ATI spectra strongly depend not only the magnitude but also the sign of the chirp-rates. In order to confirm the numerical convergence, we have repeated calculations with different spherical box sizes and the number of orbital angular momenta for the expansion of timedependent wavefunction, obtaining practically the identical ATI spectra. Thus, these puzzling results presented in Fig. 1 are not numerical artifacts.The dependence on the ATI spectra on the magnitude of | | which represents the chirp-rate can be rather easil...

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Above-threshold ionization of Mg by linearly and circularly polarized laser fields: Origin of the subpeaks in the photoelectron energy spectra

Cited by 20 publications

References 26 publications

Experimental investigation of strong-field-ionization theories for laser fields from visible to midinfrared frequencies

Experimental investigation of strong-field-ionization theories for laser fields from visible to midinfrared frequencies

Ionization in elliptically polarized pulses: Multielectron polarization effects and asymmetry of photoelectron momentum distributions

Chirp-Dependent Above-Threshold Ionization

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