SXSPM Research | Highlights

Fingerprinting Near to Far Field Transitions on Cu(111) Induced by Synchrotron Radiation

In order to realize the full potential of synchrotron x-ray scanning tunneling microscopy (SXSTM) it is essential to maintain tunneling conditions, even while high brilliance X-rays irradiate the sample surface. Different from conventional scanning tunneling microscopy, X-rays can cause a transition of the tip out of the tunneling regime. Monitoring the reaction of the z-piezo (the element that controls the tip to sample separation) alone is not sufficient, because a continuous tip current is obtained, even when the tip leaves the tunneling regime. As a solution, an unambiguous and direct way of fingerprinting such near to far field transitions of the tip that relies on the simultaneous analysis of the X-ray-induced tip and sample current has been explored. This result is of considerable importance because it opens the path to the ultimate resolution in X-ray enhanced scanning tunneling microscopy. The findings have been published in Advanced Functional Materials.