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Free keywords:
Physics, Atomic Physics, physics.atom-ph, Physics, Optics, physics.optics
Abstract:
High-order harmonic generation (HHG) in simultaneous intense near-infrared
(NIR) laser light and brilliant x rays above an inner-shell absorption edge is
examined. A tightly bound inner-shell electron is transferred into the
continuum. Then, NIR light takes over and drives the liberated electron through
the continuum until it eventually returns to the cation leading in some cases
to recombination and emission of a high-harmonic photon that is upshifted by
the x-ray photon energy. We develop a theory of this scenario and apply it to
1s electrons of neon atoms. The boosted high-harmonic light is used to generate
a single attosecond pulse in the kiloelectronvolt regime. Prospects for
nonlinear x-ray physics and HHG-based spectroscopy involving core orbitals are
discussed.
