Date/Time: 04-04-2018 - Wednesday - 05:00 PM - 07:00 PM
PCC North, 300 Level, Exhibit Hall C-E
Exploring both topographical and chemical information down to nanoscale has intrigued broad research attention. Tip-enhanced Raman spectroscopy (TERS) imaging, which combines both the high spatial resolution of Scanning Probe Microscopy (SPM) and the enhanced signal sensitivity of surface-enhanced Raman Spectroscopy, has been demonstrated as a promising technique for the near-field Raman imaging research. The quality of TERS heavily relies on the Raman signals Enhancement Factor (EF) using the metallic tip. Here, we have developed a reliable and low-cost fabrication method to prepare STM-TERS tip. Using a Sharp-Tip Silver Nanowire (ST-AgNW) introduced in our previous work, both high spatial resolution and high EF can be achieved. By putting the ST-AgNW on the platinum-iridium wire with a micromanipulator, the protruding length of ST-AgNW can be precisely controlled and reduced to less than 5 µm, which results in the minimized thermal vibration. Utilizing conical shape at the ST-AgNW apex, atomic scale resolution (~0.1 nm) STM image of Highly Ordered Pyrolytic Graphite (HOPG) has been achieved and multi-channel tunneling current can be avoided. Moreover, TERS performances of the ST-AgNW have been evaluated by approaching the ST-AgNW to monolayer graphene on the 30nm gold substrate. Owing to the small tip radius of our ST-AgNW (~5 nm), a gap mode with small mode volume between the ST-AgNW and the gold substrate can be supported when the incident laser was tightly focused into the tip-substrate gap. Comparing with the regular AgNW tips in other TERS tip preparation methods, a much higher enhancement factor (EF) from our STAgNW tip has been demonstrated by both Raman spectroscopy measurement and finite element analysis simulation.
5:00 PM–7:00 PM Apr 4, 2018 (America - Denver)
PCC North, 300 Level, Exhibit Hall C-E