Near-infrared laser spectroscopy of Nil

Abstract

Laser-induced fluorescence spectrum of Nil in the near infrared region of 714-770 nm has been recorded. Seven bands belonging to three electronic transition systems were observed and analyzed: the (0,0), (1,0), and (2,0) bands of [13.3] 2∑ + -A 2∏ 3/2 system; the (1,1) and (0,1) bands of [13.9] 2∏ 3/2-X 2Δ 5/2 system; and the (0,0) and (1,0) bands of [13.9] 2∏ 3/2-A 2∏ 3/2 system. Spectra of isotopic molecules confirmed the vibrational quantum number assignment of the observed bands. Least-squares fit of rotationally resolved transition lines yielded accurate molecular constants for the v = 0-2 levels of the [13.3] 2∑ + state, the v = 0 level of the A 2∏ 3/2, and the v = 1 level of the X 2Δ 5/2 state. The vibrational separation, ΔG 1/2, of the ground state was measured to be 276.674 cm -1. With the observation of the [13.9] 2∏ 3/2-A 2∏ 3/2 and [13.9] 2∏ 3/2-X 2Δ 5/2 transitions, we accurately determined the energy separation between the A 2∏ 3/2 and the X 2Δ 5/2 to be 163.847 cm -1. This confirms that the order of the A 2∏ 3/2 and X 2Δ 5/2 states in Nil is reversed when compared with other nickel monohalides. © 2004 American Institute of Physics.