Anomalous Vibrational Dependence of the Rotational and Hyperfine Parameters in the B4Π–X4Σ− Transition of NbO

✍ Scribed by C.T. Kingston; C.-K.D. Liao; A.J. Merer; S.J. Tang

• Publisher: Elsevier Science
• Year: 2001
• Tongue: English
• Weight: 206 KB
• Volume: 207
• Category: Article
• ISSN: 0022-2852
• DOI: 10.1006/jmsp.2001.8323

✦ Synopsis

The laser excitation spectrum of jet-cooled NbO in the region 16 000-18 000 cm -1 has been recorded at high resolution, giving rotational and hyperfine constants for the levels v = 0-3 of the B 4 state and v = 1 of the X 4 -state; zero gaps have also been measured at low resolution for some weaker bands involving higher vibrational levels. Taken together with the laser data for the B-X (0,0) band from Adam et al. (J. Chem. Phys. 94, 6240-6262 (1994)) and the Fourier transform emission data for the doublet manifold from Launila et al. (J. Mol. Spectrosc. 186, 131-143 (1997)), the new data give a very complete picture of the vibrational energy level pattern in this region. Strong irregularities in the vibrational dependences of the B 4 rotational and hyperfine constants can be interpreted in terms of spin-orbit interaction between the B 4 state and the f 2 , e 2 , and d 2 states. The interaction is strong enough that all three doublet states can be seen in absorption from the X 4 -ground state, adding to the complexity of the spectrum. The hitherto unknown σ δσ * 4 state is estimated to lie near 17 500 cm -1 , from the change of sign in the spin-rotation parameter γ of the B 4 state between v = 2 and 3.