Isocyanogen as a pyrolysis product of N-cyano-2,3-diphenyl-cyclopropeneimine

Observation of the A1A" state of isocyanogen

The A1A" state of isocyanogen, CNCN, is observed using photofragment fluorescence excitation spectroscopy in a room temperature cell and in a molecular beam. The spectra are highly congested, but progressions that correspond to the Franck-Condon active C-N-C bending vibration in the excited state are evident. Linewidth measurements indicate that the excited state lifetime is <10 ps. These measurements are consistent with previous ab initio calculations, which predicted a bent excited state with a short lifetime due to predissociation. Although we do not believe that we have observed the origin band of the electronic transition, we place an upper limit of 42,523 cm(-1) on the energy of the excited state zero point level.

Accurate Rovibrational Spectroscopic Properties of Cyanogen and Its Isotopomers

The six-dimensional potential energy surface (PES) of the most stable isomer of C(2)N(2) is investigated using the coupled cluster single and double approach with perturbative treatment of triple excitations (CCSD(T)). The full quartic force fields of this molecule and some of its isotopomers are calculated in dimensionless normal coordinates. This quartic force field has been optimized in order to reproduce the known overtones within 1 cm(-1). A set of spectroscopic constants is derived for these isotopomers using this optimized quartic force field. The full rovibrational spectrum is also given up to 1500 cm(-1) with an accuracy better than 1 cm(-1). Copyright 2001 Academic Press.