Accurate Rotational Constants, Frequencies, and Wavelengths from 12C16O2 Lasers Stabilized by Saturated Absorption
New experimental measurements of the frequency separations of 30 pairs of 12C16O2 laser lines in the 10.4 µm band and 26 pairs in the 9.4 µm band have been made with lasers stabilized to Lamb-dip-type resonances observed in the 4.3 µm fluorescent radiation. The use of a Josephson junction as the frequency mixing element simplified the measurements. Uncertainties in existing rotational constants for the laser vibrational levels were reduced 20 to 30 times and an additional rotational constant, Hv was determined for the first time. Frequency and wavelength tables with estimated uncertainties are calculated for both bands with the new constants.
KeywordsAbsolute Frequency Reference Line Laser Line Josephson Junction Beat Frequency
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- 3.For example, Freed et al. have measured the frequencies of many laser lines in some of the less abundant CO2 isotopes relative to 12C16O2 [Charles Freed, A. H. M. Ross, Robert G. O’Donnell, To be published. Also discussed in a following paper.].Google Scholar
- 6.In a separate investigation, radiation was deliberately reflected back into one of the lasers by a vibrating mirror. With low driving frequencies (5 to 50Hz), the amplitude of the driving voltage was adjusted such that the full width at half intensity of the beat frequency increased by a factor of 4 to approximately 100 kHz. There was no measurable shift in the center frequency.Google Scholar
- 7.G. Herzberg, Molecular Spectra and Molecular Structure: I. Spectra of Diatomic Molecules (D. Van Nostrand Company, Inc., Princeton, N.J., 1950), 2nd ed., and Molecular Spectra and Molecular Structure: II. Infrared and Raman Spectra (D. Van Nostrand Company, Inc., New York, 1945).Google Scholar
- 8.The fit was done initially using sums and differences of rotational constants as in Bridges and Changl and later using the constants directly. There was no difference in the results.Google Scholar
- 9.Experimental Statistics, National Bureau of Standards Handbook 91 (August 1, 1963), Superintendent of Documents, U. S. Government Printing Office, Washington, D. C. 20402, (pp. 6-1 to 6-17).Google Scholar
- 10.Recommendation of the Comite Consultatif pour la Definition du Metre, 5th Session, June 1973, at BIPM, Serves, France — discussed in the preceding paper: K. M. Evenson, F. R. Petersen, and J. S. Wells.Google Scholar