Thursday, August 3, 2017 - 8:00pm

In this talk, novel instrumentation techniques recently developed in Argonne National Laboratory to investigate quantum properties of individual nanoparticles, single molecules, and single atoms on surfaces as well as new quantum phenomena discovered by using these techniques will be presented. At the first part, the latest results of our synchrotron X-rays scanning tunneling microscope (SX-STM) will be shown. To date, synchrotron measurements vital for the characterization of materials at the nanoscale are performed by using conventional detectors. The spatial resolution of most synchrotron measurements is poor because they depend on the X-ray beam size. SX-STM enables to probe local X-ray induced currents at the atomic scale independent of the X-ray beam size and thus it has a tremendous advantage over the conventional synchrotron measurements. As the demonstrations of this nascent technique, the detection of element specific X-ray excited electrons from a single Co nanocluster, local X-ray Magnetic Circular Dichroism measured on Co and Fe thin films, and X-ray absorption spectroscopy of individual nanoparticles will be presented. At the second part, a comparative force measurement scheme using STM to determine the lateral force required to move just one atom or one molecule on a surface will be presented. Here, our latest results concerning lateral force measurements of individual molecules and molecular machines at the atomic scale using a combined STM/q+AFM set-up will be shown. Symmetry dependent lateral force and spin friction will also be discussed.

Speaker: 

Prof Saw Wai Hla

Institution: 

Argonne and Ohio Univ.

Location: 

NS2 2201