Low energy electron microscopy at cryogenic temperatures

•The design of a cryogenic low energy electron microscope is described.•Sample temperatures as low as 15 K have been reached.•Electron beam damage to pentacene is reduced by a factor of 5.4 from 300 K to 52 K.•The IV-spectra of few-layer pentacene change upon cooling. We describe a cryogenic sample chamber for low energy electron microscopy (LEEM), and present first experimental results. Modifications to our IBM/SPECS aberration-corrected LEEM instrument are presented first. These include incorporation of mechanisms for cooling the sample and its surroundings, and reduction of various sources of heat load. Using both liquid nitrogen and liquid helium, we have reached sample temperatures down to about 15 K. We also present first results for low-temperature LEEM, obtained on a three-monolayer pentacene film. Specifically, we observe a reduction of the electron beam irradiation damage cross-section at 15 eV by more than a factor of five upon cooling from 300 K down to 52 K. We also observe changes in the LEEM-IV spectra of the sample upon cooling, and discuss possible causes.