Attosecond X-rays beyond Oxygen K-edge for probing charge motion in condensed matter
Abstract
The recent rapid progress in few-cycle, carrier-envelope phase stable, high power Optical Parametric Amplifiers centered at ~1.8 micron has led to the demonstration of tabletop attosecond water window (282 to 533 eV) X-ray sources. At the present time, the photon flux of such X-ray pulses is sufficient for conducting time-resolved experiments at the Argon L-edge (250 eV), Nitrogen K-edge (400 eV) and Titanium L-edge (~460 eV), though not yet at the Oxygen K-edge (533 eV) and higher photon energies. Zenghu Chang at the University of Central Florida proposes to develop a tabletop attosecond X-ray source for studying ultrafast charge dynamics in solid state materials. The objectives are to demonstrate high repetition rate attosecond pulses whose spectra cover the 500 to 1500 eV range. The spatially and temporally coherent X-rays will be generated by driving high-order harmonic generation in noble gases with a high-power femtosecond laser centered at 4.1 micron. Such a laser is not commercially available and will be designed and constructed by Chang’s group. This mid-infrared Chirped Pulse Amplification laser is anticipated to deliver 17 fs, 5 mJ pulses at 1.6 kHz. Proof-of-principle transient absorption experiments will be performed to illustrate the capability of the X-ray source to observe light-induced charge motion in ultrathin quartz crystals and other materials with element specificity. This may open a new way to extend metrology of optoelectronic devices into the petahertz domain, which is important for Air Force applications in high-speed signal processing and communication. The program also provides a unique opportunity to train the next generation of experts in high power mid-infrared laser technology, attosecond X-ray sources and ultrafast condensed matter physics.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Aug 12, 2021
- Source ID
- FA95502010295
Entities
People
- Zenghu Chang
Organizations
- Air Force Office of Scientific Research
- United States Air Force
- University of Central Florida Board of Trustees