Berlin 2001 – scientific programme

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K: Kurzzeitphysik

K 1: Short time-scale dynamics and diagnostics

K 1.2: Talk

Monday, April 2, 2001, 16:50–17:05, EB107

Nanosecond Mirror Electron Microscope - a new fast Surface Probe — •Harry Kleinschmidt and Oleg Bostanjoglo — Technische Universität Berlin, Optisches Institut, Sekr. P 1-1, Straße des 17. Juni 135, D-10623 Berlin

A pulsed mirror electron microscope (MEM) was developed for imaging fast laser pulse-induced processes on metal and semiconductor surfaces. It consists of an UV laser pulse-driven photoelectron gun, beam focussing and imaging lenses, and an electromagnet separating the illuminating and imaging electrons. The specimen is the reflecting electrode of a mirror lens. The short-time electron images (5 ns FWHM) are captured by an intensified CCD-camera and digitized. A pulse from a second laser (532 nm, 20ns) is focussed on the specimen, launching fast processes. Since the MEM exploits electrons reflected by surface electric potentials and scattered by emitted vapour, it is a sensitive probe for near-threshold modifications of the first top atomic layers. Changes of the back surface are tracked in dielectrics via capacitively coupled potential variations.