Aufbau eines Rastertunnelmikroskopes mit integriertem Zylinderspiegelanalysator

A cylindrical mirror analyser has been integrated in a scanning tunneling microscope (STM). With this analyser the energy distribution of backscattered electrons has been measured. The electrons originate from a field emission tip positioned close to the investigated samples. The influence of the field emission tip on the electron trajectories has been calculated numerically. As a consequence of these calculations a further electrode has been introduced near the tip to optimize the elccron optical properties of the analyser. To enable a special tip preparation, which is necessary for the operation of the STM in the field emission mode, the setup is equiped with facilities for field ion and field emission nucroscopy. Using the instrument in the STM-mode, atomic resolution of the (100) surface of copper has been achieved. Beyond these test measurements a detailed investigation of the step structure on Cu(100) and various Cu(11n) surfaces has been performed (n = 7, 11, 13 and 19). The step structure is very sensitive to remanent trace contamination, which decorate the steps and prohibit kink diffusion. Therefore great care was taken in thesample preparation. Because of the high mobility of the kink atoms at metal surfaces the step edges appear frizzy in the STM topographs. It became possible to measure the activation energy for kinks although individual kinks can not be resolved by STM. These measurements give also some strong hints for an attractive interaction between steps at intermediate distances of 4 to 5 atomic diameter and a repulsive interaction at shorter separation. The step-step interaction plays an important rule for the stability of crystal faces. In the case of Cu(117) the short range repulsion between the steps dominates and stabilizes this surface. The attractive interaction at greater distances leads to a facetting of the investigated vicinal surfaces. This result is discussed in the context of former experiments studying the thermal roughening transition