The application of low energy electron microscopy and photoemission electron microscopyto organic thin films

Abstract

Over the last few years, low energy electron microscopy and photoemission electronmicroscopy have been successfully used to study the growth dynamics of various organicsemiconductors. In the present work, the recent advances in the application of surfacesensitive electron microscopy techniques to organic thin films are reviewed, and therequirements for successful imaging of organic molecules in low energy electron microscopyand photoemission electron microscopy are discussed. Starting from a discussion of thebasic design features of the microscopes, a variety of imaging modes are presented toillustrate the type of information that can be gained from in situ surface sensitive electronmicroscopy. In photoemission microscopy, the contrast greatly depends on theillumination source that is used for imaging. Using a frequency doubled femtosecondTi:sapphire laser as a light source for photoemission, even electronic states within themolecules can be directly used for imaging in two-photon photoemission electronmicroscopy. The article focuses on the two linearly conjugated molecules pentacene(C22H14) andanthracene (C14H10) as model systems.