Mid-infrared magnetic rotation spectroscopy (MRS) experiments on nitric oxide (NO) are quantitatively modeled by theoretical calculations. The verified theory is used to specify an instrument that can make in situ measurements on NO and NO2 in the Earth’s atmosphere at a sensitivity level of a few parts in 1012 by volume per second. The prototype instrument used in the experiments has an extrapolated detection limit for NO of 30 parts in 109 for a 1-s integration time over a 12-cm path length. The detection limit is an extrapolation of experimental results to a signal-to-noise ratio of one, where the noise is considered to be one-half the peak-to-peak baseline noise. Also discussed are the various factors that can limit the sensitivity of a MRS spectrometer that uses liquid-nitrogen-cooled lead-salt diode lasers and photovoltaic detectors.
© 1996 Optical Society of America
Original Manuscript: December 9, 1994
Revised Manuscript: September 25, 1995
Published: February 20, 1996
Thomas A. Blake, Charles Chackerian, and James R. Podolske, "Prognosis for a mid-infrared magnetic rotation spectrometer for the in situ detection of atmospheric free radicals," Appl. Opt. 35, 973-985 (1996)