Raman analysis of common gases using a Multi-pass Capillary Cell (MCC)

Christopher M. Gordon; William F. Pearman; J. Chance Carter; James Wai-Jeung Chan; S. Michael Angel

doi:10.1117/12.795586

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11 September 2008 Raman analysis of common gases using a Multi-pass Capillary Cell (MCC)

Christopher M. Gordon, William F. Pearman, J. Chance Carter, James Wai-Jeung Chan, S. Michael Angel

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Proceedings Volume 7061, Novel Optical Systems Design and Optimization XI; 70610L (2008) https://doi.org/10.1117/12.795586
Event: Optical Engineering + Applications, 2008, San Diego, California, United States

Abstract

The Raman analysis of common, non-absorbing gases was performed using an 18@1 fiber-optic probe coupled to a multi-pass capillary cell (MCC) for signal enhancement. The MCC is fabricated by metal-coating, using silver or other highly reflective metals, the inside of a 1-2 mm diameter glass capillary using commercially available silvering solutions and provides enhancements up to 30-fold over measurements using the fiber-optic probe alone. The design of the MCC is simple and the device is easy to incorporate into an experimental setup making it suitable for remote and <i>in-situ</i> analysis. Although the MCC is functionally similar to liquid-core waveguides that have been previously described in the literature, the MCC is not based on total internal reflection and so the refractive index of the analyte is not important to the operation of the device. The principle of operation of the MCC is similar to mirror-based multiple pass Raman cells, however, the MCC is not expensive, alignment is trivial and an optical path length up to several meters in length is possible. With our first-generation silver-coated MCCs, limits of detection were determined to be 0.02% and 0.2% for CH₄ and CO₂ respectively. In this talk we will discuss optimization of the MCC and issues involved in its use.

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Christopher M. Gordon, William F. Pearman, J. Chance Carter, James Wai-Jeung Chan, and S. Michael Angel "Raman analysis of common gases using a Multi-pass Capillary Cell (MCC)", Proc. SPIE 7061, Novel Optical Systems Design and Optimization XI, 70610L (11 September 2008); https://doi.org/10.1117/12.795586

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