Highly reproducible low temperature scanning tunneling microscopy and spectroscopy with in situ prepared tips

An in situ tip preparation procedure compatible with ultra-low temperature and high magnetic field scanning tunneling microscopes is presented. This procedure does not require additional preparation techniques such as thermal annealing or ion milling. It relies on the locale lectric-field-induced deposition of material from the tip on to the studied surface. Subsequently, repeated indentations are performed on to the sputtered cluster to mechanically anneal the tip apex and thus to ensure the stability of the tip. The efficiency of this method is confirmed by comparing the topography and spectroscopy data acquired with either unprepared or in situ prepared tips one pitaxial graphene grown on Ru (0001). We demonstrate that the use of in situ prepared tips increases the stability of the scanning tunneling images and the reproducibility of the spectroscopic measurements. (C) 2012 Elsevier B.V. All rights reserved.