| Autor: |
Christopher P. Palmer, Brian K. Keller, Michael D. DeGrandpre |
| Rok vydání: |
2004 |
| Předmět: |
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| Zdroj: |
SPIE Proceedings. |
| ISSN: |
0277-786X |
| DOI: |
10.1117/12.579777 |
| Popis: |
Light-guiding fused silica capillary tubing has promising applications in the field of chemical sensors. Light propagation in these waveguides occurs within the fuse d silica capillary wall as opposed to liquid core waveguides where light traverses the solution-filled inner core. The electric field of light within the capillary wall extends slightly into the capillary inner diameter as an evanescent wave. An evaluation of the optical absorbance characteristics of these novel capillaries was performed by coupling the light source from a spectrophotometer into a capillary waveguide flow cell. A series of four thiacyanine dyes in methanol solutio n provided distinct absorbance peaks throughout the visible spectrum (400-800 nm). Evanescent absorbance values show a linear dependence upon capillary length up to ~10 m (with 150 µ m inner diameter). Evanescent absorbance measurements were nonlinear with solution concentration for all capillary lengths and may be attributed to adsorption of the ionic dye on the capillary fused silica inner surface. The waveguide effective pathlength ratio (EPLR) was determined by comparing evanescent absorbance values to conventional measurements in a 0.1 mm pathlength cuvette. The EPL is on the order of 10 |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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