We are evaluating non-contact, stand-off Raman spectroscopy to determine the relative concentrations of the oxidized and reduced forms of OCPs at temperatures between 800 °C and 1000 °C, and pressures of about 10 atm. Using cw and pulsed Raman spectroscopy, in combination with a pressurized high-temperature sample chamber, we have optimized the operating parameters such as laser wavelength, laser intensity, collection optic design, focal spot size, etc. and measured Raman spectra of various OCP materials at high temperatures. To extract from the Raman spectra relevant information such as the concentration ratio of a material in different oxidation states, the measured data needs to be processed, and statistical modeling and multivariate calibration need to be performed.
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John Kirtley, Victoria Leichner, Hergen Eilers, "Raman spectroscopy of oxygen carrier particles in harsh environments ," Proc. SPIE 10639, Micro- and Nanotechnology Sensors, Systems, and Applications X, 106390Z (8 May 2018);