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This illustration shows how the AFM tip is used to deposit gold nanoparticles on a surface from a colloidal solution. The area is then illuminated in a spectrometer beam and the locally enhanced spectrum is acquired. After deposition, the particles may be imaged to determine the precise location and orientation of the particles to the sample surface. As a variation, the AFM cantilever may be used to modulate the beam by serving as a local shutter above the enhanced particle region.
The Raman spectrum is given of a BPE film on quartz that is enhanced by a cluster of ten particles that were deposited by an AFM tip. The area is in diameter that is well below the diffraction limit of the Raman excitation laser. No BPE was detectable on this surface before the particles were deposited. The corresponding AFM image is shown with the diameter gold particles.
The surface enhanced Raman spectrum is given of a BPE film from a single particle deposited by an AFM. No BPE was detectable on this surface before the particle was deposited.
The FTIR microscope spectrum (top) is shown for a cluster of AFM deposited gold particles on a thin silicone film. The enhanced area is in diameter as shown in the corresponding AFM image. For comparison, the unenhanced film on an adjacent region is not detectable (bottom spectrum).
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