SPring-8, the large synchrotron radiation facility

Date & Time: 15:30 - , July 25, 2005

Speaker: Dr. Christoph Quitmann
Affiliation: Swiss Light Source (SLS)

Abstract
　　At the Swiss Light Source (SLS) there are 2 experiments underway to study ultra-fast dynamics of materials using x-rays.
　　The first experiment focuses on magnetization dynamics. Magnetic micro particles are excited using fast magnetic field pulses (~200 ps) and are imaged after a variable time delay (Δt) using a photoemission electron microscope (PEEM). This provides quantitative information about the topology, frequency and amplitude of the magnetic excitations. In permalloy squares (L = 6 µm) there are three distinct modes associated with the domains, the domain walls and the vortex. The field pulse initially excites coherent magnetization precession within the domains. These later transfer their energy to the domain wall and the vortex mode respectively. Using objects of different shape size and orientation we provide quantitative information for all three modes and study the coupling of the modes.
　　The second experiment uses bunch slicing by a high power laser to produce electron packages of < 100 fs. These electron bunches then create ultra-short x-ray pulses of 5-17 keV energy in an in-vacuum undulator. This bunch slicing experiment is under construction and I will report on the concept, the status and first preliminary results.