AVS 56th International Symposium & Exhibition
    Exhibitor Workshops Tuesday Sessions
       Session EW-TuA

Paper EW-TuA6
Difference Raman for Enhancing Image Resolution by Accurate Tip Positioning of an Atomic Force Probe that Enhances or Shadows the Raman Signal

Tuesday, November 10, 2009, 3:40 pm, Room Exhibit Hall 1

Session: Exhibitor Workshop
Presenter: R. Dekhter, Nanonics Imaging Ltd., Israel
Authors: J. Ernstoff, Nanonics Imaging Ltd., Israel
R. Dekhter, Nanonics Imaging Ltd., Israel
H. Taha, Nanonics Imaging Ltd., Israel
A. Israel, Nanonics Imaging Ltd., Israel
D. Lewis, Nanonics Imaging Ltd., Israel
A. Lewis, Hebrew University of Jerusalem, Israel
Correspondent: Click to Email

Tip enhanced Raman scattering (TERS) has been shown as a potential technique for overcoming limitations of conventional micro Raman spatial resolution and for other apertureless near-field optical measurements based on plasmonic interactions. In this talk we will compare the resolutions obtainable by such plasmonic enhancement techniques as compared to a method we have developed based on the ultra-sensitive nature of difference Raman. In this latter technique an AFM probe with an exposed tip geometry that is optimized to block a nanometric region of a sample will be used in conjunction with difference Raman to obtain significant improvements in Raman image resolution over conventional far-field scattering. For this new imaging protocol one has to have not only exposed tip geometries but also an AFM system that can modulate and scan the probe independently of the sample scanning required for Raman imaging systems. The tip scanning is required for optimizing the position of the probe tip for maximizing the shadow effect on the sample in the near-field. The independent tip movement is required for bringing the probe in and out of the near-field of the sample so that a difference Raman can be recorded at each pixel and an image formed as the sample is scanned point by point. All of the above in terms of the Shadow protocol are predicated by having an AFM system that has a completely free optical axis from above and is completely independent from the lens of the micro-Raman. Results will be shown on structured thin films of strained silicon on silicon to show the relative fidelity of these imaging modalities. The results indicate that Shadow Near Field Scanning Optical Microscopy (sNSOM) is a powerful technique that can be applied for significant improvements in Raman imaging spatial resolution.