Materials Science Research Lecture

Abstract: In this talk, I will discuss using high harmonic generation to create extreme ultraviolet (XUV) X-ray pulses with energies covering 10-150 eV for spectroscopic purposes. Specifically, in transient XUV spectroscopy, a material's temporal response is measured using an XUV probe after photoexcitation with a <5 fs visible light pulse The measured core-level transition contains information on both the photoexcited electronic and structural dynamics. If the core-hole perturbation is accounted for, analysis of the transient XUV signal gives the heat and charge transfer rates between different elemental species in a material or junction. For example, the conversion of photoexcited electrons to polarons is measured in α-Fe2O3. The time-resolved energy of electrons and holes, as well as their correlation with the acoustic and optical phonon bath, is measured in Si and Ge. Finally, the charge and heat transport is measured between each component of a metal-insulator-semiconductor junction (Ni-TiO2-Si) using the Ni, Ti, and Si X-ray edges.

More about the Speaker: Scott Cushing is a new Assistant Professor at the California Institute of Technology. He received his B.S. and Ph.D. from West Virginia University and was a DOE EERE Postdoctoral Fellow under Prof. Stephen Leone. He is currently exploring how table-top X-ray sources and entangled photons can be used to understand ultrafast charge and heat transport in multiple-material junctions.