Fourier Transform Infrared Emission Spectroscopy of NaCl and KCl.

The infrared emission spectra of NaCl and KCl have been recorded at high resolution with a Fourier transform spectrometer. A total of 929 lines belonging to 8 vibrational bands, 1-0 to 8-7, for Na35 Cl, 252 lines of 1-0, 2-1, and 3-2 bands of Na37 Cl, and 355 lines of 1-0, 2-1, 3-2, and 4-3 bands of K35 Cl have been measured and combined with the existing microwave and millimeter-wave data to obtain a set of refined molecular constants. The data for Na35 Cl and Na37 Cl have also been fitted to determine the Dunham Yij constants and mass-reduced Dunham constants Uij . In one fit all Uij 's were treated as adjustable parameters while in a second fit only Ui 0 's and Ui 1 's were allowed to vary freely with the remaining Uij constants determined by the constraints imposed by the Dunham model. In addition, the internuclear potential energy parameters were determined by fitting the entire NaCl data set to the eigenvalues of the Schrodinger equation containing a parameterized potential energy function.