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Fiber-optic surface plasmon resonance for vapor phase analyses
Yoon-Chang Kim1, Soame Banerji, Jean-Francois Masson
1Department of Chemistry and Biochemistry, Arizona State University, Tempe, AZ 85287-1604, USA.
The Analyst
|May 25, 2005
Summary
This study introduces modified fiber-optic sensors using surface plasmon resonance (SPR) to measure the refractive index (RI) of gases. These novel sensors enable direct detection of gas RI changes and air density variations.
Area of Science:
- Optoelectronics
- Sensor Technology
- Physical Chemistry
Background:
- Surface Plasmon Resonance (SPR) sensors are typically designed for liquid RI measurements near water's RI (1.3330).
- Standard silica-based SPR sensors have a high refractive index (RI), limiting their sensitivity to gases with RI near 1.0008 (air).
Purpose of the Study:
- To develop fiber-optic SPR sensors capable of directly measuring the refractive index (RI) of gases.
- To overcome the limitations of high RI silica waveguides for gas sensing applications.
Main Methods:
- Modification of probe geometry in silica-based fiber SPR sensors.
- Tuning the SPR coupling wavelength/angle pair for enhanced sensitivity.
- Utilizing tapered fiber SPR sensors for direct RI measurements.
Main Results:
- Demonstrated direct determination of RI changes for gas species.
- Successfully measured density changes in dry air using the modified SPR sensor.
- Achieved sensitivity to RI variations in the range of 1.00 to 1.30.
Conclusions:
- Modified tapered fiber SPR sensors are effective for direct gas RI and air density measurements.
- The probe geometry modification allows for tuning SPR coupling for gas sensing.
- This approach expands the application of SPR sensors to gas phase analysis.