Metastable impact electron emission microscopy: principles and applications

Metastable impact electron emission microscopy (MIEEM) provides a mesoscopic visualization of surfaces by electrons emitted owing to metastable He*-atom (2(3)S) impacts and a spectroscopic contrast by an imaging energy filter. Since the metastable He* atoms excite the outermost surface electrons solely, a high surface sensitivity is achieved. The MIEEM imaging mode was realized by the combination of the He* source with the spectroscopic low energy electron microscope (SpecLEEM), thus allowing a reliable tracing of spatiotemporal surface processes within the field of view of ca 50 mu m diameter. A few examples of MIEEM-applications are presented: a study of the chemical composition of insulating islands appearing on lanthanum-doped SrTiO3(100) surfaces as well as the first successful employment of MIEEM for the in situ imaging of surface reactions. Copyright (C) 2006 John Wiley & Sons, Ltd.