Potential barrier effects in high-order harmonic generation by transition-metal ions

Abstract

Frolov, M. V.; Manakov, N. L.; and Starace, Anthony F., "Potential barrier effects in high-order harmonic generation by transition-metal ions" (2010 The experimental finding of significant enhancement or suppression of particular harmonics generated by the ionic component of laser-produced plasmas of transition-metal atoms is explained theoretically in terms of the standard three-step scenario for strong-field harmonic generation, taking into account the potential barrier effects that lead to a strong 3p → 3d electric dipole transition that dominates the photoionization cross sections of the outer subshells of those ions.

High-order harmonic generation by atoms in a few-cycle laser pulse: Carrier-envelope phase and many-electron effects

“…Figure 2 predicts such atom-specific dynamical features (whose occurrence in HHG by long pulses was discussed recently in Refs. [12,15,16]) to occur also in single-cycle HHG spectra. Moreover, Fig.…”

“…This parametrization is attractive since (i) it is valid for harmonics with energies in the region of the HHG plateau cutoff, which are precisely the ones used to produce attosecond pulses, and (ii) it involves a field-free atomic parameter σ (r) that describes atomic structure effects on HHG spectra [12][13][14][15][16]. However, the explicit form of the EWP is known only for monochromatic [12] and two-color [15] fields, while the possible manifestation of atomic structure features in the few-cycle regime and their modification by CEP effects remain unexplored.…”

Analytic confirmation that the factorized formula for harmonic generation involves the exact photorecombination cross section

“…Second, based on the parametrization (1), both enhancement and suppression of individual harmonics observed in experiments on the HHG spectra of laser-produced plasmas of singly-charged ions of the transition metals Cr and Mn [21,22] were explained in Ref. [23] as originating from "giant dipole" resonance features in the photoionization cross sections of Cr + and Mn + ions. Third, Ref.…”

New Approaches in Frequency Conversion of Laser Radiation in Plasma Plumes

“…The enhancement of a single harmonic can be attributed to the broadband resonances of the ions of few metals, such as V, In, Cd, Cr, Cd, and Mn. These "giant" resonances have been experimentally confirmed in the literature [26,28,29] and discussed recently in a few theoretical studies [7,[30][31][32]. However, in previous studies using multi-cycle pulses, the intensity of enhanced harmonics was only a few times higher compared with those neighboring harmonic orders.…”