HIGH RESOLUTION INFRARED SPECTROSCOPY OF NO USING TUNABLE PbSSe LASERS
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Date
1972
Journal Title
Journal ISSN
Volume Title
Publisher
Ohio State University
Abstract
A detailed high resolution $(\leq 3\times 10^{-5} cm^{-1})$ study of indivudual absorption lines in the fundamental vibration-rotation band of NO has been made using tunable PbSSe semiconductor lasers operating near $5.3 \mu$m. These absorption spectra reveal previously unresolved fine structure in the R and Q branches due to A doubling, nuclear hyperfine splitting and Zeeman splitting. Experiments were performed at low pressure $(\leq 1 Torr)$ using small gas cells (4-10 cm) with magnetic fields up to 50 kG. Absorption spectra were obtained by sweeping the frequency of the laser through the absorption lines while measuring the cell transmission. The R(15/2)$_{1/2}$ absorption shows the Doppler profile at 0.2T with two A doubled components separated by 318 MHz. Each of these components splits into two apparent absorption lines in a magnetic field along the propagation direction. The measured splitting $(g = 0.028)$ is in excellent agreement with the calculated values using parameters deduced from microwave experiments. The R(15/2)$_{3/2}$ absorption appears as a single line due to the smallness of the A type spllitting (29MHz) relative to the Doppler width (127 MHz). This line splits into 14 major components in a longitudinal magnetic field with splittings in good agreement with the calculated values. Numerous absorption lines near the heads of the $Q_{1/2}$ and $Q_{3/2}$ branches have been studied. Nuclear hyperfine splitting as well as A doubling have been observed in the Q(1/2)$_{1/2}$, Q(3/2)$_{1/2}$ and Q(5/2)$_{1/2}$ lines and compared with the calculated lineshape. Excellent agreement is obtained with calculations using nuclear hyperfine coupling parameters deduced from microwave measurements.
Description
This work was sponsored by the Department of the Air Force.
Author Institution: Lincoln Laboratory, Massachusetts Institute of Technology
Author Institution: Lincoln Laboratory, Massachusetts Institute of Technology