Absorption of radiation from sodium dimer molecular states correlating to $\mathrm{Na}\mathrm{}\left(3s\right)-\mathrm{Na}\mathrm{}\left(3s\right)\mathrm{}$ is investigated theoretically. Vibrational bound and continuum transitions from the singlet $X{}^1{\Sigma }_g^{+}$ state to the first excited $A{}^1{\Sigma }_u^{+}$ and $B{}^1{\Pi }_u$ states and from the triplet $a{}^3{\Sigma }_u^{+}$ state to the first excited $b{}^3{\Sigma }_g^{+}$ and $c{}^3{\Pi }_g$ states are studied quantum-mechanically. Theoretical and experimental data are used to characterize the molecular properties, taking advantage of knowledge recently obtained from ab initio calculations, spectroscopy, and ultracold atom collision studies. The quantum-mechanical calculations are carried out for temperatures in the range from 1000 to 3000 K, and are compared with previous calculations and measurements where available.

• Received 15 August 2000

DOI:https://doi.org/10.1103/PhysRevA.63.032516