A Breakdown of the Watson-Type Hamiltonian for Some Asymmetric-Top Molecules: The Case of the Spin-Multiplet State

✍ Scribed by K. Yokoyama; W.C. Lineberger; K.M.T. Yamada

• Publisher: Elsevier Science
• Year: 1996
• Tongue: English
• Weight: 163 KB
• Volume: 178
• Category: Article
• ISSN: 0022-2852
• DOI: 10.1006/jmsp.1996.0161

✦ Synopsis

A breakdown of the standard Watson-type rotational Hamiltonian was suggested for a molecule with H 2 XYZ structure [S ˇ. Urban and K. M. T. Yamada, J. Mol. Spectrosc. 160, 279-288 (1993)]. This breakdown is due to a near-resonant interaction between the ground state rotational levels and rotational levels in an excited vibrational state. This interaction has been observed in the excited electronic state of H 2 CCC 0 ( 2 A 1 state) by high-resolution autodetachment spectroscopy. The centrifugal distortion coupling term and nonvanishing matrix elements for electronic spin doublet and triplet states are described using Hund's case (b) basis sets. The results are used to interpret the centrifugal distortion couplings between the n 6 and n 9 modes and the vibrational ground states in H 2 CCC 0 . Centrifugal distortion coupling constants C ac 6 Å 1.0723(2) 1 10 04 and C ab 9 Å 01.5397(5) 1 10 05 were obtained for this system.