Far- and Mid-Infrared Emission Spectroscopy of LiH and LiD

High-resolution Fourier transform spectra of LiH and LiD were recorded in the far-infrared region, 100-360 cm-1, and the mid-infrared regions, 800-1200 cm-1 and 2000-3000 cm-1. A total of 261 pure rotational lines and 678 rovibrational lines were measured for the isotopomers 6LiH(D) and 7LiH(D). Molecular constants for the X1Sigma+ ground state in the form of mass-dependent Dunham Yij's and mass-independent Dunham Uij's were determined from a data set of 1476 lines, consisting of our measured line positions and previously reported microwave, millimeter-wave, and infrared lines. An effective internuclear potential for the ground electronic state where the Born-Oppenheimer part is modeled as a parameterized modified-Morse function was also determined from a fit of the data. Copyright 1998 Academic Press.