Hyperfine Structure of the［14. 6］2Δ5/2-X 2Δ5/2（9，0）Band of NiI

The（9，0）band of the［14. 6］2Δ5/2 - X2Δ5/2 transition of NiI in the visible region has been studied at high resolution using laser vaporization / reaction supersonic free jet expansion and laser induced fluorescence spectroscopy. Spectrum taken at a resolution of about 80 MHz shows the resolved hyperfine structure which is caused by an unpaired electron in the excited state interacting with the large magnetic moment of the I nucleus with nuclear spin I = 5/2. The rapid decrease in hyperfine width of the low J lines in the v=9 level suggests that the hyperfine coupling in the［14. 6］2Δ5/2 state conforms to the Hund's Case aβ coupling scheme. Accurate rotational and hyperfine parameters for the［14. 6］2Δ5/2 state have been obtained，which indicate that the v=9 level is perturbed.