Knowledge Bank

The ammonia $8-12\mu m$ bands are often used for calibrating diode laser spectra both because of the wide spectral extent of the bands and because the gas is convenient to use. However, the accuracies of available $NH3$ frequencies have often been inadequate for absolute calibration of diode spectra. We have significantly improved the $NH3$ transition frequencies by measuring them with respect to $CO2$ standards using Fourier transform Spectroscopy. Besides improving the calibration of new spectra, the results to be presented can be used to recalibrate previously recorded laser spectra. This list, which is intended for use as a calibration reference, is the result of measurements of a spectrum of both $NH3$ and $CO2$ (in the same cell), recorded using the McMath 1-meter Fourier transform Spectrometer $(0.005cm-1resolution)$ at Kitt Peak. Results over the frequency range $800\le \upsilon \le 1150cm-1$ will be presented. Using the well established laser frequencies for $CO2$ as a reference an error analysis will also be presented.