Infrared laser spectroscopy of jet-cooled carbon clusters: the bending dynamics of linear C9.

We report improved measurements for the nu 6 antisymmetric stretch fundamental and observation of the (nu 6 + nu 15)-nu 15 and (nu 6 + 2 nu 15)-2 nu 15 hot bands of the linear C9 carbon cluster by direct absorption diode laser spectroscopy of a supersonic carbon cluster beam. Analysis of these bands characterizes C9 as a semirigid molecule with a bending potential similar to that of C5 and further evidences the alternation in degree of rigidity of linear carbon clusters with the g-u symmetry of the HOMO.