Knowledge Bank

Laser induced fluorescence spectrum of NiI in the near infrared region 714 - 770 nm has been recorded and analyzed. Eleven bands belonging to four electronic transition systems have been observed: the $(0,0),(1,0)$, and (2,0) bands of $[13.3]2\Sigma +-A\mathrm{<mrow\; data-mjx-texclass="ORD">2</mrow>}\Pi 3/2$ system; the (0,0), (1,1) and (0,1) bands of the $[13.9]2\Pi 3/2-X\mathrm{<mrow\; data-mjx-texclass="ORD">2</mrow>}\Delta 5/2$ system; the (0,0) and (1,0) bands of $[13.9]2\Pi 3/2-A2\Pi 3/2$ system; and the (0,0), (1,1) and (0,1) bands of the $[14.0]2\Phi 7/2-X2\Delta 5/2$ system. Spectra of isotopic molecules confirmed the vibrational quantum number assignment of the observed bands. Least squares fit of observed rotational lines yielded accurate molecular constants for the $[13.3]2\Sigma +,[14.0]2\Phi 7/2$ and the $A2\Pi 3/2$ electronic states of NiI. Hot band transition from the $v=1$ level of the $X2\Delta 5/2$ state gives $\Delta G1/2=276.67cm-1$. The $A2\Pi 3/2$ state was determined to be only $163.85cm-1$ above the $X2\Delta 5/2$ state.