Knowledge Bank

A collection of 6070 spectroscopic line positions for hydrogen fluoride and deuterium fluoride, which consists of all microwave and infrared $X1\Sigma +$ ground electronic state data, and the $B1\Sigma +X1\Sigma +$ emission band system data, has been employed in a weighted least-squares fit directly to the radial Hamiltonian operators of the $B1\Sigma +$ and $X1\Sigma +$ electronic states. The radial Hamiltonian operator model includes first- and second-order corrections to the Born-Oppenheimer approximation and was derived from the landmark theoretical work of $Watsona$. The principle isotopomer fitting strategy of Le $Royb$ was incorporated in the least-squares fit. A total of 54 adjustable parameters was required to obtain a satisfactory representation of the experimental data, with a reduced standard deviation of 1.03. In addition, a collection of highly accurate quantum-mechanically meaningful rotational and centrifugal distortion constants was calculated from the derived Hamiltonian operators of the two electronic states.