Nitric Oxide Isotopic Analyzer Based on a Compact Dual-Modulation Faraday Rotation Spectrometer
AbstractWe have developed a transportable spectroscopic nitrogen isotopic analyzer. The spectrometer is based on dual-modulation Faraday rotation spectroscopy of nitric oxide isotopologues with near shot-noise limited performance and baseline-free operation. Noise analysis indicates minor isotope (15NO) detection sensitivity of 0.36 ppbv·Hz−1/2, corresponding to noise-equivalent Faraday rotation angle (NEA) of 1.31 × 10−8 rad·Hz−1/2 and noise-equivalent absorbance (αL)min of 6.27 × 10−8 Hz−1/2. White-noise limited performance at 2.8× the shot-noise limit is observed up to ~1000 s, allowing reliable calibration and sample measurement within the drift-free interval of the spectrometer. Integration with wet-chemistry based on acidic vanadium(III) enables conversion of aqueous nitrate/nitrite samples to gaseous NO for total nitrogen isotope analysis. Isotopic ratiometry is accomplished via time-multiplexed measurements of two NO isotope transitions. For 5 μmol potassium nitrate samples, the instrument consistently yields ratiometric precision below 0.3‰, thus demonstrating potential as an in situ diagnostic tool for environmental nitrogen cycle studies. View Full-Text
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Zhang, E.; Huang, S.; Ji, Q.; Silvernagel, M.; Wang, Y.; Ward, B.; Sigman, D.; Wysocki, G. Nitric Oxide Isotopic Analyzer Based on a Compact Dual-Modulation Faraday Rotation Spectrometer. Sensors 2015, 15, 25992-26008.
Zhang E, Huang S, Ji Q, Silvernagel M, Wang Y, Ward B, Sigman D, Wysocki G. Nitric Oxide Isotopic Analyzer Based on a Compact Dual-Modulation Faraday Rotation Spectrometer. Sensors. 2015; 15(10):25992-26008.Chicago/Turabian Style
Zhang, Eric; Huang, Stacey; Ji, Qixing; Silvernagel, Michael; Wang, Yin; Ward, Bess; Sigman, Daniel; Wysocki, Gerard. 2015. "Nitric Oxide Isotopic Analyzer Based on a Compact Dual-Modulation Faraday Rotation Spectrometer." Sensors 15, no. 10: 25992-26008.