Fiber-optic oxygen sensor using molybdenum chloride cluster luminescence

Ghosh, Ruby N.; Baker, Gregory L.; Ruud, Cory; Nocera, Daniel G.

doi:10.1063/1.125180

Cited by 95 publications

(75 citation statements)

References 14 publications

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“…(iv) the pumping and collection efficiencies of the current setup (Figure 4 ) are the same as in [5] We used the 3M fibers for sensor operating at lower temperatures (125 -150 °C) and will use the Ceramoptec and Fiberguide fibers for higher temperature applications. The 3M and Fiberguide optical fibers have Suprasil cores, a high purity synthetic fused silica manufactured by flame hydrolysis of SiCl 4 .…”

Section: Clean Uncoatedmentioning

confidence: 99%

“…13 Table 2: Summary of the processing scheme, cluster/sol-gel composite film characteristics and sensing measurements of fibers C, D, E and H (see Figure 7) and slide 38Q (see Figure 13). Table 3: Calculated performance of four different high temperature optical fibers (1, 2, 4 and 5) compared to the fiber used (3) for our previous room temperature optical fiber oxygen sensor [5]. The signal for the other fibers are calculated relative that of fiber 1.…”

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confidence: 99%

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Fiber Optical Micro-Detectors for Oxygen Sensing in Power Plants

Baker¹,

Ghosh²,

Osborn³

et al. 2005

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A reflection mode fiber optic oxygen sensor is being developed that can operate at high temperatures for power plant applications. The sensor is based on the 3 O 2 quenching of the red emission from hexanuclear molybdenum chloride clusters. Two critical materials issues are the cluster's ability to withstand high temperatures when immobilized in a porous the sol-gel support, and whether after heating to high temperatures, the sol-gel matrix maintains a high and constant permeability to oxygen to support rapid quenching of luminescence. We used a composite materials approach to prepare stable sensing layers on optical fibers. We dispersed 60 w/w% of a pre-cured sol-gel composite containing the potassium salt of molybdenum clusters (K 2 Mo 6 Cl 14 ) into a sol-gel binder solution, and established the conditions necessary for deposition of sol-gel films on optical fibers and planar substrates. The fiber sensor has an output signal of 5 nW when pumped with an inexpensive commercial 365 nm ultraviolet light emitting diode (LED). Quenching of the sensor signal by oxygen was observed up to a gas temperature of 175 °C with no degradation of the oxygen permeability of the composite after high temperature cycling. On planar substrates the cluster containing composite responds within <1 second to a gas exchange from nitrogen to oxygen, indicating the feasibility of real-time oxygen detection. (10×) showing a sol-gel monolith containing MM5 pulverized using a mortar and pestle, 25 -250 µm particle size, (b) a sol-gel monolith (no clusters), 1 -2 µm particle size, and (c) dark field image (100×) showing a sol-gel monolith containing MM5 pulverized via ball milling, 2 -8 µm particle size. 3 20Figure 8 Typical dip coating results for deposition of composite / sol-gel binder blends 1000 µm diameter fibers. Details of the fiber fabrication and resultant measurements are in Table 2. 21Figure 9: Processing schemes used for fibers and planar sample (slide) 38Q. The principal differences between 38Q and the fibers is that (i) the binder used for 38Q contained molybdenum clusters whereas that for the fibers did not and (ii) 38Q was cured at 200 °C whereas the fibers were cured at 70 °C.The same cluster/sol-gel monolith was used for all samples. 22Figure 10: Specifications of the optical fibers used for oxygen fiber sensor fabrication and for testing the mechanical properties of the sol-gel film. Figure 13: High temperature fiber sensor luminescence and oxygen quenching for Fiber D (see Figure 12 for details). Here we demonstrate oxygen quenching of 1.3 ± 0.2 at 175 °C. 28Figure14: Thermal dependence of the emission spectra for film 38Q cured at 200 C for 30 minutes. The emission intensity is a function of temperature, but the line-shape is temperature independent. All spectra were sampled in 99.999% nitrogen environments. The cluster source was MM8 and the film concentration is (5±1.1) × 10 20 clusters/cm 3 based on an estimated film thickness of (700 ± 300) nm. The result demonstration that room temperature quenching ratio...

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Section: Clean Uncoatedmentioning

confidence: 99%

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confidence: 99%

Fiber Optical Micro-Detectors for Oxygen Sensing in Power Plants

Baker¹,

Ghosh²,

Osborn³

et al. 2005

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“…The emission spectra of the current Mo 6 Cl 12 compound dissolved in 6 M HCl compared with previous results from Ghosh [4] 13 Figure 7. The emission spectra of the current Mo 6 Cl 12 compound prior to thermal cycling in air and 0.001% oxygen Figure 8.…”

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confidence: 96%

Fiber Optical Micro-Detectors for Oxygen Sensing in Power Plants

Baker¹,

Ghosh²,

Osborn³

2003

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“…To prepare a fiber optic sensor based on Mo 6 Cl 12 , Ruud dispersed Mo 6 Cl 12 in poly[1-trimethylsilyl-1-propyne] (PTMSP), and used a dipping technique to immobilize the composite at the cleaved end of a silica optical fiber. Ghosh and co-workers [5] demonstrated a fast room temperature fiber optic sensor based on oxygen quenching of the luminescence from the PTMSP/Mo 6 Cl 12 composites. While the PTMSP support is adequate for room temperature applications, is unable to withstand the high temperatures associated with combustion in a power plant.…”

Section: Introductionmentioning

confidence: 99%

Fiber Optical Micro-Detectors for Oxygen Sensing in Power Plants

Baker¹,

Ghosh²,

Osborn³

2004

View full text Add to dashboard Cite

A reflection mode fiber optic oxygen sensor that can operate at high temperatures for power plant applications is being developed. The sensor is based on the 3 O 2 quenching of the red emission from hexanuclear molybdenum chloride clusters. High temperature measurements of the emission of clusters in sol gel films show that the luminescence intensity from the films follow a 1/T relationship from room temperature to 150 °C, and then declines at a slower rate at higher temperatures. The large number of photons available at 230 °C is consistent with simple low cost optics for fiber optic probes based on the emission from clusters in sol gel films.3

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Fiber-optic oxygen sensor using molybdenum chloride cluster luminescence

Cited by 95 publications

References 14 publications

Fiber Optical Micro-Detectors for Oxygen Sensing in Power Plants

Fiber Optical Micro-Detectors for Oxygen Sensing in Power Plants

Fiber Optical Micro-Detectors for Oxygen Sensing in Power Plants

Fiber Optical Micro-Detectors for Oxygen Sensing in Power Plants

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