Near Field Scanning Optical Microscopy

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Near Field Scanning Optical Microscopy (NSOM,
SNOM, NFOM) Stephanie Pruzinsky Group
Meeting, June 6, 2002
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Near-Field v. Far-Field
Near-Field (Evanescent)
Light with spatial frequencies are present in the
tip but decay within one wavelength dmin 1
20 nm has been reported dmin 50 100nm is more
common
Far-Field (Diffraction Limited)
dmin ?/2 - ?
http//www.nrel.gov/sss/nsom.html
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Typical NSOM Setup
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WITEC NSOM Setup
http//www.witec.de/snom.html
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NSOM Probe Techniques
Aperture
Apertureless
STOM
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NSOM Aperture Probes
Chemical Etching
Fiber-Pulling
Evanescent Decay
Aluminum Deposition
300 nm
300 nm
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WITEC Microfabricated NSOM Probes
wafer with 228 tips
Si cantilever
hollow Al pyramid
tip 100 nm
http//www.witec.de/snom.html
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NSOM Applications

• Fluorescence imaging
• tagged in situ biological samples
• phase-separated or patterned films and
  monolayers
• single dye molecules
• Microspectroscopy
• quantum dots
• nanoparticles
• plasmonic crystals
• photonic crystals
• Laser ablation
• localized MALDI mass spectrometry
• Photolithography, localized photochemistry

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NSOM Fluorescence Imaging of Single Dye Molecules
0
2.1
13.5
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NSOM Spectroscopy of Quantum Dots
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NSOM of 2D Photonic Crystals
100 nm