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Evanescent wave excited luminescence from levitated quantum dot modified colloids
W Neil Everett1, Richard E Beckham, Kenith Meissner
1Department of Mechanical Engineering, Department of Chemical Engineering, and Department of Biomedical Engineering, Texas A&M University, College Station, Texas 77843, USA.
Langmuir : the ACS Journal of Surfaces and Colloids
|July 20, 2007
Summary
Quantum dot modified polystyrene (QDPS) colloids show luminescence for measuring potential energy profiles. This method offers new possibilities for advanced microscopy techniques.
Area of Science:
- Colloid and Surface Science
- Nanotechnology
- Optical Physics
Background:
- Investigating the behavior of colloidal particles near surfaces is crucial for understanding various physical and chemical processes.
- Evanescent wave excitation is a powerful tool for probing surface phenomena at the nanoscale.
Purpose of the Study:
- To explore the use of evanescent wave excited luminescence from quantum dot modified polystyrene (QDPS) colloids for measuring their potential energy profiles.
- To compare luminescence-based measurements with traditional scattering methods.
Main Methods:
- Utilized confocal microscopy, emission spectra, flow cytometry, and temporal measurements.
- Characterized luminescence of different-sized PS colloids modified with different-sized QDs.
- Electrostatic levitation of QDPS colloids above a planar glass surface.
Main Results:
- Potential energy profiles derived from luminescence intensity showed excellent agreement with scattering data and theoretical predictions.
- QDPS luminescence intensity exhibited an exponential dependence on height, consistent with evanescent wave scattering.
- Demonstrated the potential for QDPS luminescence in advanced microscopy applications.
Conclusions:
- Evanescent wave excited QDPS luminescence is a viable method for characterizing colloid-surface interactions.
- This technique offers advantages over scattering, enabling new microscopy applications like spectral multiplexing and enhanced resonance modes.
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