Knowledge Bank

Fulminic acid belongs to the class of quasilinear molecules. Precise ab initio methods are not available to reproduce the quasilinear behavior of the molecule. In particular, the calculations cannot predict the multitude of accidental resonance interactions. We have now analyzed the infrared spectra of HCNO and its isotopomers $H13CNO$ and $H13C15NO$ up to $7000cm-1$. More then 30000 lines could be assigned. The low symmetry of the molecule and the anharmonic quasilinear bending mode lead to an extraordinarily rich array of interactions. Most of the interactions could be classified into a network of resonance systems. As a result of such classifications, it has been possible to identify dark states. An overview and comparison of the different network in HCNO, $H13CNO$ and $H13C15NO$ will be discussed. The term value schemes built up with the help of the Ritz combination principle will be presented.