Diode-laser-based sensor for ultraviolet absorption measurements of atomic mercury
A new sensor has been developed for measuring atomic mercury using absorption spectroscopy with 254-nm radiation generated from two sum-frequency-mixed diode lasers. Beams from a 375-nm external-cavity diode laser and a 784-nm distributed feedback diode laser are mixed in a beta-barium-borate crystal to generate approximately 4 nW of ultraviolet radiation. The development of the sensor is described along with extensive characterization experiments in a mercury vapor cell in the laboratory. An accuracy of ±6% in the absolute concentration of atomic mercury has been demonstrated by comparison with equilibrium vapor pressure calculations. The detection limit is approximately 0.1 parts per billion of atomic mercury in a meter path length for 300-K gas and a 10-s integration time. The insensitivity of the sensor to broadband attenuation is demonstrated. Measurements of collision-broadening coefficients for air, N2, Ar, and CO2 are reported, and implementation of wavelength-modulation spectroscopy with the sensor is demonstrated. Finally, results are presented from measurements with the sensor in situ in the exhaust stream of an actual coal-fired combustor.
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- 1.J.H. Pavlish, E.A. Sondreal, M.D. Mann, E.S. Olson, K.C. Galbreath, D.L. Laudal, S.A. Benson, Fuel Process. Technol. 82, 89 (2003)Google Scholar
- 2.www.epa.gov/mercury (2006)Google Scholar
- 3.W.J. O’Dowd, R.A. Hargis, E.J. Granite, H.W. Pennline, Fuel Process. Technol. 85, 533 (2004)Google Scholar
- 4.D.L. Laudal, T.D. Brown, B.R. Nott, Fuel Process. Technol. 65, 157 (2000)Google Scholar
- 5.D.L. Laudal, J.S. Thompson, J.H. Pavlish, L.A. Brickett, P. Chu, Fuel Process. Technol. 85, 501 (2004)Google Scholar
- 6.E.J. Granite, Obstacles in the development of mercury continuous emissions monitors, in Proc. 20th Annu. Int. Pittsburgh Coal Conf., Pittsburgh, PA, 15–19 September 2003, paper 30-1Google Scholar
- 12.T.N. Anderson, R.P. Lucht, S. Priyadarsan, K. Annamalai, J.A. Caton, Appl. Opt., in pressGoogle Scholar
- 15.G. Herzberg, Atomic Spectra and Atomic Structure (Dover, New York, 1944)Google Scholar
- 20.NIST web page, http://physics.nist.gov/PhysRefData/Handbook/Tables/mercurytable1.htmGoogle Scholar
- 22.SNLO nonlinear optics code available from A.V. Smith, Sandia National Laboratories, Albuquerque, NM 87185-1423, USA through www.sandia.gov/imrl/XWEB1118/xxtal.htmGoogle Scholar
- 29.T.E. Jenkins, Optical Sensing Techniques and Signal Processing (Prentice-Hall, Englewood Cliffs, NJ, 1987)Google Scholar
- 30.J.R. Taylor, An Introduction to Error Analysis: The Study of Uncertainties in Physical Measurements (University Science Books, Sausalito, CA, 1997)Google Scholar
- 36.J.K. Magnuson, T.N. Anderson, R.P. Lucht, U. Vijayasarathy, H. Oh, K. Annamalai, submitted to Energy FuelsGoogle Scholar