Low cost photoelectron yield setup for surface process monitoring

Online monitoring of surface reactions allows an immediate quality control of surface preparations, both for scientific and high through-put purposes. Several approaches for UHV process control with submonolayer sensitivity require cost-intensive instrumentation, such as a low energy electron microscope (LEEM),¹ a reflection high energy electron diffraction (RHEED)² unit, or a photoemission electron microscope (PEEM).³ We report here a simple setup for controlling surface processes in vacua up to 1 millibar pressure. A pulsed ultraviolet (UV) light source is employed to probe the photoelectron yield which is related to the work function of the surface of interest. The advantage of a pulsed light source is that it allows distinguishing between continuously generated ions or electrons of a reaction and the photocurrent from the surface. Our instrumentation is responsive to changes within the first atomic monolayer and is simple to be implemented in existing UHV preparation chamber systems. To...