113 research outputs found
Phase-matched enhancements of high-harmonic soft X-rays by adaptive wave-front control with a genetic algorithm
We demonstrate the enhancement of high-harmonic soft-X-ray generation by adaptive wave-front control of a 745-nm Ti:sapphire laser by use of a 59-channel membrane deformable mirror, combined with a genetic algorithm, for the first time to our knowledge. The harmonics ranging from 17Â nm to 28Â nm were enhanced by factors up to 13. The numerical calculations illustrate that the enhancements of the plateau harmonics are due to macroscopic phase-matching effect, whereas those of the cutoff harmonics are due to the increase in focal intensity.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47046/1/340_2003_Article_1400.pd
Extreme-ultraviolet pump-probe studies of one femtosecond scale electron dynamics
Studies of ultrafast dynamics along with femtosecond-pulse metrology rely on
non-linear processes, induced solely by the exciting/probing pulses or the
pulses to be characterized. Extension of these approaches to the
extreme-ultraviolet (XUV) spectral region opens up a new, direct route to
attosecond scale dynamics. Limitations in available intensities of coherent XUV
continua kept this prospect barren. The present work overcomes this barrier.
Reaching condition at which simultaneous ejection of two bound electrons by
two-XUV-photon absorption becomes more efficient than their one-by-one removal
it is succeeded to probe atomic coherences, evolving at the 1fs scale, and
determine the XUV-pulse duration. The investigated rich and dense in structure
autoionizing manifold ascertains applicability of the approach to complex
systems. This initiates the era of XUV-pump-XUV-probe experiments with
attosecond resolution.Comment: 27 page
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