Correlated Topographic and Spectroscopic Imaging Beyond Diffraction Limit by Atomic Force Microscopy Metallic Tip-Enhanced Near-Field Fluorescence Lifetime Microscopy
A new approach is demonstrated for simultaneous topographic and spectroscopic imaging applying near-field optics (NSOM) with spatial resolution beyond the optical diffraction-limit. The method combines atomic force microscopy (AFM) in the metallic-tip tapping mode and near-field scanning confocal fluorescence lifetime imaging microscopy (FILM). The AFM metallic tip was formed by sputter-coating a Si tapping mode tip with Au to form a spherulitic shape at the tip apex, allowing a high local field enhancement under laser illumination, which was necessary for a strong optical signal. A simulation used to finite element method (FEM) to further evaluate the near-field enhancement originating from the metallic Au-coated AFM tapping mode tip. We have demonstrated that spatially mapping the change in fluorescence lifetime and intensity is a promising approach to semi-quantitative and chemically specific imaging at AFM spatial resolution. The spherulitic Au-coated AFM tip not only gives ad equate spatial AMF tapping-mode imaging spatial resolution but is apparently environmentally friendly to soft samples, such as polymeric dye-labeled nano-spheres and even biological specimens like POPO-3 labeled DNA.
- Research Organization:
- Pacific Northwest National Lab., Richland, WA (US), Environmental Molecular Sciences Laboratory (US)
- Sponsoring Organization:
- US Department of Energy (US)
- DOE Contract Number:
- AC06-76RL01830
- OSTI ID:
- 15004145
- Report Number(s):
- PNNL-SA-37833; 6508; KC0301020
- Journal Information:
- Review of Scientific Instruments, Journal Name: Review of Scientific Instruments Journal Issue: 7 Vol. 74; ISSN 0034-6748; ISSN RSINAK
- Country of Publication:
- United States
- Language:
- English
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