15min:

ALBERTO GAMBI, Dipartimento di Scienze e Tecnologie Chimiche dell'Università di Udine, Via Cotonificio 108, I-33100 Udine, Italy; GIOVANNI MORUZZI, Dipartimento di Fisica ``Enrico Fermi'' dell'Università di Pisa and INFM, Via Filippo Buonarroti 2, I-56127 Pisa, Italy; GOTTFRIED PAWELKE AND HANS BÜRGER, Anorganische Chemie, FB 9, Universität-Gesamthochschule, D-42097 Wuppertal, Germany.

Difluoromethanimine, F₂C=NH, is a planar, asymmetric rotor close to the oblate symmetric top limit, with =0.8928. The first successful synthesis of this molecule was carried out by Bürger and Pawelke in 1988. In the present work we present an investigation of the in-plane ₁ fundamental, N-H stretching, centered at 3042.3 cm^-1; this band, of symmetry species A', presents a hybrid ab\/ -type contour with a prominent Q head and wide P and R branches. The difficulties encountered in the assignment of this band are due both to systematic line overlappings and to interactions with dark states --- consisting of combination bands in which at least three vibrational quanta are involved --- these interactions being particularly strong for 13\le K_c\le 16. The capabilities of the ``Multi-Molecule Ritz Program'', presented at this conference in 1996, have been enhanced by adding a ``feed-back loop'' which calculates the best-fit Watsonian parameters directly from the Ritz data-base. This has led to a list of approximately 2300 assigned lines belonging to the investigated band. These assignments, and the perturbations encountered, will be discussed.