Submicrometer fiber-optic chemical sensors: Measuring pH inside single cells. Progress report, October 1990--August 1993
Starting from scratch, we went in two and a half years to 0.04 micron optical microscopy resolution. We have demonstrated the application of near-field scanning optical microscopy to DNA samples and opened the new fields of near-field scanning spectroscopy and submicron opto- chemical sensors. All of these developments have been important steps towards in-situ DNA imaging and characterization on the nanoscale. Our first goal was to make NSOM (near-field scanning optical microscopy) a working enterprise, capable of ``zooming-in`` towards a sample and imaging with a resolution exceeding that of traditional microscopy by a factor of ten. This has been achieved. Not only do we have a resolution of about 40 nm but we can image a 1 {times} 1 micron object in less than 10 seconds. Furthermore, the NSOM is a practical instrument. The tips survive for days or weeks of scanning and new methods of force feedback will soon protect the most fragile samples. Reproducible images of metal gratings, gold particles, dye balls (for calibration) and of several DNA samples have been made, proving the practicality of our approach. We also give highly resolved Force/NSOM images of human blood cells. Our second goal has been to form molecular optics (e.g., exciton donor) tips with a resolution of 2--10 nm for molecular excitation microscopy (MEM). We have produced such tips, and scanned with them, but only with a resolution comparable to that of our standard NSOM tips. However, we have demonstrated their potential for high resolution imaging capabilities: (1) An energy transfer (tip to sample) based feedback capability. (2) A Kasha (external heavy atom) effect based feedback. In addition, a novel and practical opto-chemical sensor that is a billion times smaller than the best ones available has been developed as well. Finally, we have also performed spatially resolved fluorescence spectroscopy.
- Research Organization:
- Univ. of Michigan, Ann Arbor, MI (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- FG02-90ER61085
- OSTI ID:
- 10107801
- Report Number(s):
- DOE/ER/61085-3; ON: DE94004160; BR: KP0101000
- Resource Relation:
- Other Information: PBD: [1993]
- Country of Publication:
- United States
- Language:
- English
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