TF03		15min2:04

S. A. BEATON, J. M. BROWN, Physical and Theoretical Chemistry Laboratory, South Parks Road, Oxford, UK, OX1 3QZ ; Y. ITO, Department of Mechanical Engineering, Nagaoka University of Technology, 1603-1 Kamitomioka, Nagaoka, Niigata 940-21, Japan .

The (0,0) band of the A³_u-X³_g^- transition of NCN, observed previously by Herzberg and Travis, has been reinvestigated by means of laser-induced fluorescence at 329\,nm. A frequency doubled dye laser was used to record the spectrum of NCN downstream of a microwave discharge through N₂ and CF₄ in He. From the rotational analysis, improved values for the molecular constants of NCN in both states were obtained, including \Lambda-type doubling parameters for the ³_u upper state.

The main molecular constants obtained were

.5cm \begincenter X³_g^-:\hspace.5cmB''₀₀₀=0.3972458(95)cm^-1\hspace.5cm\lambda''=0.79402(50)cm^-1

.25cm A³_u:\hspace.5cm B'₀₀₀=0.3966487(95)cm^-1\hspace0.5cm A'=--37.4493(38)cm^-1

.2cm

T'₀₀₀=30383.8110(51)cm^-1 \endcenter

.3cm

The B values (and hence bond lengths) are very similar in the two states and therefore the spectrum is dominated by v = 0 transitions.

The (010)-(010) band occurs in a similar wavelength region, the excited state of this transition exhibiting the Renner-Teller effect. Analyses of both the ³ _g-³ _u and the ³ _g-³ _u components of this hot band will be presented.

.5cm