Knowledge Bank

Calculations are reported of the visible absorption and dispersion spectra of diatomic ($Li2,Na2,LiAl,\dots )$ metal vapors employing a model that incorporates theoretically and experimentally derived potential energy curves and transition dipole moment functions. The calculated ro-vibronic transition energies and intensities, which include high rotational states $(Jmax\approx 100)$ and incorporate the J-dependence of absorption strengths, are combined with appropriate Voigt lineshapes in interpretation of transmission measurements in $Li2$ and $Na2$ vapors obtained in a high-temperature ($T\approx 1600$ to $1800\circ K$) flow apparatus. The theoretical and experimental results in these cases provide an opportunity to characterize the temperature, pressure, and concentration profiles in the apparatus and to verify conditions of local thermal equilibrium, whereas calculated absorption spectra for LiAl provide a basis for attempts at spectral absorption measurements in this case. Comments are made on possible measurements of the resonant refractive index of metal vapors employing interferometric detection in the flow apparatus for comparisons with the calculated dispersion profiles.