Knowledge Bank

By using a color center laser or a tunable diode laser, we have made accurate frequency measurements on the 2-0 band of CO, the $0002-0000$, $2001-0000$ and $1201-0000$ bands of $N2O$, and many bands of OCS. All measurements have been made by locking the laser to the absorption maximum of the line to be measured and then measuring the frequency difference between the tunable laser and appropriate harmonics or combinations of one or two $CO2$ lasers. In some cases the tunable laser frequency was measured against a CO laser which was in turn measured against combinations of two $CO2$ laser frequencies. In keeping with infrared calibration tradition, the 2-0 absorption band of CO has been measured with the greatest accuracy. Saturated absorption measurements with a line-width of about 3 MHz have made it possible to mesure the CO absorption frequencies with an absolute accuracy of about 100 kHz ($0.000004cm-1$). The importance of the pressure shift of the absorption frequencies will be discussed. An atlas of accurate OCS absorption frequencies will also be described. $\mathrm{<mrow\; data-mjx-texclass="ORD">\ast </mrow>}$This work was supported in part by the NASA Upper Atmosphere Research Office.