ME07		15min3:30

R. D. VAN ZEE, J. P. LOONEY, J. T. HODGES, Process Measurements Division, National Institute of Standards and Technology, Gaithersburg, MD 20899.

This paper investigates the effects of cavity design and laser bandwidth on quantitative cavity ring-down spectroscopy using the ^rR transitions of the X(v=0) to b(v=0) band of molecular oxygen. It is found that failure to account for laser bandwidth leads to systematic errors in the number densities determined from measured ring-down signals. By fitting the frequency integrated expression for the ring-down signal and using the measured laser lineshapes, excellent agreement between measured and and predicted number densities is found. The quantitative measurement of gas densities over a wide dynamic range will be presented.