Laser spectroscopy of NiI: new electronic states and hyperfine structure.

Two new electronic transition systems, namely, the 14.0Phi(7/2)-Chi (2)Delta(5/2) and the 15.7Phi(5/2)-Chi (2)Delta(5/2) transitions were observed and analyzed using laser vaporization/reaction supersonic free jet expansion and high resolution laser induced fluorescence spectroscopy. In addition, the (v, 0) bands with v=6-10 of the 14.6Delta(5/2)-Chi (2)Delta(5/2) transition were found to be perturbed by the 15.7Phi(5/2) state. The interaction between the 14.6Delta(5/2) and the 15.7Phi(5/2) states is evident in the progressive increase in hyperfine width of rotational lines of the 14.6Delta(5/2)-X (2)Delta(5/2) transition as the vibrational quantum number increases. Deperturbation procedures were successfully applied to analyze the interaction between these two states. All observed spectra show partially resolved hyperfine structure, and the hyperfine width decreases rapidly as J increases suggested that the hyperfine structure conforms to the Hund's case a(beta) coupling scheme. Accurate molecular and hyperfine constants for the 14.0Phi(7/2), the 14.6Delta(5/2) and the 15.7Phi(5/2) states were obtained and analyzed.