15min:

W. S. TAM, JIANJUN YE AND A. S-C. CHEUNG, Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong..

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 +} - A ² _3/2 system; the (0,0), (1,1) and (0,1) bands of [13.9] ² _3/2 - X ² _5/2 system; the (0,0) and (1,0) bands of [13.9] ² _3/2 - A ² _3/2 system; and the (0,0), (1,1) and (0,1) bands of the [14.0] ² _7/2 - X ² _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 +}, [14.0] ² _7/2 and the A ² _3/2 electronic states of NiI. Hot band transition from the v = 1 level of the X ² _5/2 state gives G_1/2 = 276.67 cm^-1. The A ² _3/2 state was determined to be only 163.85 cm^-1 above the X ² _5/2 state.