A high-speed transmission electron microscope was developed for probing laser-induced fast nonperiodical processes on the nanosecond time scale. 7–11 ns illuminating electron pulses—up to three—are produced by a laser pulse-driven photocathode. The electron gun can be used both for nanosecond exposure and conventional stationary operation. The introduced microscope is operated in three different modes for investigations of laser treated thin films: (1) Bright-field imaging, tracking changes of the texture and transport of neutral material; (2) dark-field imaging, mapping transient plasmas; and (3) selected area diffraction to study fast phase transitions. Presently, the space resolution is ≈200 nm.

No abstract

No abstract

Forced and free oscillations of magnetic domain walls and Bloch lines are excited in Nio.83Feo.i7 films a t 0.1 to 31 MHz by high frequency magnetic fields and visualized b y stroboscopic electron microscopy (time resolution 1 ns). Resonance of single and coupled oscillators, 'subharmonics', and Bloch line+ross-tie annihilation are directly observed. Specific mass and relaxation time are determined, being m = 2.6 X kg/m, TBL M 15 ns for a Bloch line. Erzwungene und freie Schwingungen von magnetischen Bereichswanden und Blochlinien werden in Nio,saFeo,17 Schichten im Bereich 0,l bis 31 MHz durch hochfrequente Magnetfelder angeregt und durch stroboskopische Elektronenmilrtoskopie abgebildet (zeitliche Auflosung 1 ns). Resonanzen von Einzel-und gekoppelten Schwingern, sowie Blochlinien-Stachel-Vernichtung werden direkt beobachtet. Spezifische Masse und Relaxationszeit werden bestimmt. Sie betragen m = = 2,6 X lo-' kg/m2, z = 30 ns fur eine 9O0-NBel-Wand sowie m B L z kg/m, -CBL M 15 11s fur eine Blochlinie. kg/m2, T = 30 ns for a 90O-NBel wall and mBL z

No abstract