The nu6 + nnu9 Levels of Dicyanoacetylene

In addition to the previously observed band system nu6 + (n + 1)nu9-nnu9 with n = 0 to 7, Deltal = 0, and l = n near 611 cm-1, we have identified the nu6 + (n + 1)nu9 - (n + 2)nu9 system with n = 0 to 6, Deltal = 0, and l = n + 2 near 397 cm-1. From these bands the rovibrational levels of the states (v6, nv9) with n < 4 have been determined and spectroscopic parameters have been obtained taking into account rotational and vibrational l-type resonances. Effective anharmonicity constants x69 and g69 have been calculated also for levels with n >/= 4. Copyright 1998 Academic Press.