10min:

DINES CHRISTEN, Institute of Physical and Theoretical Chemistry, University of Tübingen, Germany; MICHAEL H. PALMER, Department of Chemistry, University of Edinburgh, Scotland, UK; FLEMMING HEGELUND, Department of Chemistry, Aarhus University, Denmark.

The microwave spectrum of 1,2,4-triazine has been recorded in the Ku- and Ka-bands using a conventional stark spectrometer. The low-J lines appeared close to the frequencies predicted for the ground state from the high resolution FTIR-studies, but to secure a correct assignment of higher J Q-branch transitions, a microwave-microwave double resonance experiment was done for a few pairs of transitions sharing a common level. 145 transitions were recorded with J_max= 42, K_a,max= 33, and K_c,max= 11. A simultaneous fit to MW pure rotational transitions and to the rotational structure of selected IR-bands led to a determination of rotational and all 5 quartic centrifugal distortion constants.