NEW YEAR INFRARED WAVENUMBER STANDARDS BY FOURIER SPECTROSCOPY IN VACUUM

Abstract

$^{1}$ D.H. Rank, A.H. Guenther, G.D. Saksena, J.N. Shearer and T.A. Wiggins, J. Opt. Soc. Am. 47, 8, 686 (1957). $^{2}$ G. Guelachvili, Nouv. Rev. Optique Appliquee 3, 6, 317 (1972). $^{3}$ G. Guelachvili, These ORSAY (1973). $^{4}$ P. Heminger, F.C. De Lucia and W. Gordy, Phys. Rev. Lett. 25, 20, 1397 (1970).Author Institution: Laboratoire AIME COTTONThe 2 -- 0 band lines of $^{12}C^{16}O$, at about $4260 cm^{-1}$, are the most frequently used ones for the wavenumber calibration of near infrared spectrometers. The values of these wavenumbers, up to now considered as standards, have been given a long time ago by D.H. Rank and his co-workers$.^{1}$ The High Information Fourier Spectrometer, built at Laboratoire AIME COTTON, is now operating in $Vacuum^{2}$ and provides absolute wavenumber measurements. It has been used to measure the 2 - 0 band of $^{12}C^{16}O,$ which lines were directly referred, in the experiment, to the Krypton 86 Standard line at 16 $507.6373 cm^{-1}$. The estimated relative error on the lines position is $3 \times 10^{-8}$. The relative precision is increased by 16 when compared with that of the previous standards. Comparison between the two sets of CO lines shows some discrepancies. The $B_{0}$ rotational $constant^{3}$ leads, combined with the $B_{0}$ value given by P. Heminger $et al^{4}$ leads to the following Velocity of Light $c = 299 792.46 ( \pm 0.070)$ km/s. The precision on the i.r. and the r.f. $B_{0}$ rotational constant values have the same order of magnitude