THE ULTRA VIOLET SPECTUM OF THE NCN RADICAL
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Date
1996
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Ohio State University
Abstract
The (0,0) band of the $\tilde{A}^{3}\Pi_{u}-\tilde{X}^{3}\Sigma^{+}_{g}$ transition of NCN, observed previously by Herzberg and Travis $^{a}$, 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 $N_{2}$ and $CF_{4}$ in $He^{b}$. From the rotational analysis, improved values for the molecular constants of NCN in both states were obtained, including A-type doubling parameters for the $3\Pi$ upper state.The main molecular constants obtained were $$ \tilde{X}^{3}\Sigma^{+}_{g}:\qquad B^{\prime\prime}_{000}=0.3972458(95) \mbox{ cm }^{-1}\qquad X^{n}=0.79402(50)\mbox{ cm}^{-1} $$ $$ \tilde{A}^{3}\Pi_{u}^{+}:\qquad B^{\prime}_{000}=0.3966487(95)\mbox{cm}^{-1}\qquad A^{\prime}=37.4493(38)\mbox{cm}^{-1} $$ $$ T^{\prime}_{000}=30388.8110(51)\mbox{cm}^{-1} $$ THE $B$ values (and hence bond lengths) are very similar in the two states and therefore the spectrum is dominated by $\Delta_{t}=0$ 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 $^{3}\Delta_{g}-3^\Pi_{u}$ and the $^{3}\Sigma_{g}-^{3}\Pi_{u}$ components of this hot band will be presented.
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$^{a}$G. HERZBERG AND D. N. TRAVIS, Can. J. Phys. 42, 1658-1675(1964). $^{b}$G. P. SMITH, R. A. COPELAND AND D. R. CROSLEY, J. Chem. Phys. 91, 1987-1993 (1989).
Author Institution: Physical and Theoretical Chemistry Laboratory; Department of Mechanical Engineering, Nagaoka University of Technology
Author Institution: Physical and Theoretical Chemistry Laboratory; Department of Mechanical Engineering, Nagaoka University of Technology