15min:

HIDEYUKI TAKADA, YOSHIHIRO SUMIYOSHI AND YASUKI ENDO, Department of Pure and Applied Sciences, College of Arts and Sciences, The University of Tokyo, 153-8902 Tokyo, Japan; KENNOSUKE HOSHINA, Department of Chemistry, School of Science, The University of Tokyo, 113-0033 Tokyo, Japan.

New electronic transitions of a carbon chain radical containing a nitrogen atom have been observed by LIF spectroscopy. The radical was produced in a supersonic jet by a pulsed discharge of HC₃N diluted to 0.3% with 3atm Ar. We confirmed that the radical contains a nitrogen atom from the fact that the spectrum was not observed when C₂H₂ was used as a precursor.
About ten vibronic bands with a 50nsec radiative lifetime have been observed in a region from 27000 to 27400 cm^-1. The observed bands could be classified as ²_3/2-²_3/2 and ²-² vibronic bands. The lower state rotational constants of the vibronic bands have been determined to be 0.07537(1) and 0.07932(5) cm^-1 for the and states, respectively. The upper states of ²-² bands have very large spin-rotation constants, which should be denoted as ^(\pm) subjected to a small Renner-Teller interaction. The new molecule has been tentatively assigned to be the C₄N radical. We performed an UMP2 level ab initio calculation with 6-311G** basis sets for the C₄N radical. The estimated rotational constant in the ground state was 0.077 cm^-1. This value agrees well with the observed rotational constants.