skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Mechanisms of ultrahigh-order harmonic generation

Abstract

We analyze mechanisms of high-order harmonic generation from two-center molecules at large internuclear separations in linearly polarized laser fields. Since laser-driven electrons acquire instantaneous kinetic energies of up to 8 times the ponderomotive potential U{sub p}, recombination at an appropriately placed nucleus leads to ultrahigh-order harmonic emission [P. Moreno, L. Plaja, and L. Roso, Phys. Rev. A 55, R1593 (1997)]. By solving the time-dependent Schroedinger equation for model systems, we show that this mechanism is only efficient if the single-particle orbital of the electron is coherently delocalized over the two potential wells. This is realized in the ground state of a one-electron molecular ion. In a neutral molecule or in a molecular ion created by ionization of a neutral molecule at large internuclear distance, the coherence is destroyed by electron-electron correlation.

Authors:
 [1]
  1. Max Planck Institute for Nuclear Physics, Saupfercheckweg 1, D-69117 Heidelberg (Germany)
Publication Date:
OSTI Identifier:
20786595
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review. A; Journal Volume: 72; Journal Issue: 5; Other Information: DOI: 10.1103/PhysRevA.72.053816; (c) 2005 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
74 ATOMIC AND MOLECULAR PHYSICS; DISTANCE; ELECTRON CORRELATION; ELECTRONS; EMISSION; GROUND STATES; HARMONIC GENERATION; KINETIC ENERGY; LASER RADIATION; MOLECULAR IONS; MOLECULES; PHOTOIONIZATION; PHOTON-MOLECULE COLLISIONS; PONDEROMOTIVE FORCE; POTENTIALS; RECOMBINATION; SCHROEDINGER EQUATION; TIME DEPENDENCE

Citation Formats

Lein, Manfred. Mechanisms of ultrahigh-order harmonic generation. United States: N. p., 2005. Web. doi:10.1103/PHYSREVA.72.0.
Lein, Manfred. Mechanisms of ultrahigh-order harmonic generation. United States. doi:10.1103/PHYSREVA.72.0.
Lein, Manfred. Tue . "Mechanisms of ultrahigh-order harmonic generation". United States. doi:10.1103/PHYSREVA.72.0.
@article{osti_20786595,
title = {Mechanisms of ultrahigh-order harmonic generation},
author = {Lein, Manfred},
abstractNote = {We analyze mechanisms of high-order harmonic generation from two-center molecules at large internuclear separations in linearly polarized laser fields. Since laser-driven electrons acquire instantaneous kinetic energies of up to 8 times the ponderomotive potential U{sub p}, recombination at an appropriately placed nucleus leads to ultrahigh-order harmonic emission [P. Moreno, L. Plaja, and L. Roso, Phys. Rev. A 55, R1593 (1997)]. By solving the time-dependent Schroedinger equation for model systems, we show that this mechanism is only efficient if the single-particle orbital of the electron is coherently delocalized over the two potential wells. This is realized in the ground state of a one-electron molecular ion. In a neutral molecule or in a molecular ion created by ionization of a neutral molecule at large internuclear distance, the coherence is destroyed by electron-electron correlation.},
doi = {10.1103/PHYSREVA.72.0},
journal = {Physical Review. A},
number = 5,
volume = 72,
place = {United States},
year = {Tue Nov 15 00:00:00 EST 2005},
month = {Tue Nov 15 00:00:00 EST 2005}
}
  • This paper describes second harmonic generation which is a promising surface diagnostic that will alloys surface studies under ambient pressure and studies of liquid-solid and solid-solid interfaces. The structure and composition of the interface can be determined by this method. This metho d is demonstrated for Fe-18Cr-3Mo (100) in ultrahigh vacuum. (AIP)
  • Tunable coherent radiation in the vicinity of 64 nm has been produced by third-harmonic generation of the output of an ultrahigh-spectral-brightness ArF* source in various imple gaseous media. The following performance parameters of the ArF* system are used: pulse energy, approx.300 mJ; pulse duration, approx.7 nsec; spectral width, <260 MHz; beam divergence, approx.5 ..mu..rad x 15 ..mu..rad; and repetition rate up to 10 Hz. Third-harmonic generation with peak powers up to 30 W has been observed in an apparatus that eliminates photoabsorption of the third harmonic in the differential pumping range.
  • When an intense, plane-polarized, laser pulse interacts with a plasma, the relativistic nonlinearities induce a third-harmonic polarization. A phase-locked growth of a third-harmonic wave can take place, but the difference between the nonlinear dispersion of the pump and driven waves leads to a rapid unlocking, resulting in a saturation. What become third-harmonic amplitude oscillations are identified here, and the nonlinear phase velocity and the renormalized electron mass due to plasmon screening are calculated. A simple phase-matching scheme, based on a resonant density modulation, is then proposed and analyzed.
  • We report a study of the enhancement of the intensity of the 27th-harmonic radiation produced during the high-order harmonic generation from the GaAs plasma by controlling the chirp of the fundamental Ti:sapphire laser radiation. The influence of Ga and As ions on the enhancement of the 27th-harmonic radiation is also studied.