Knowledge Bank

The analysis of the spectra of fulminic acid up to $7000cm-1$ has revealed a large number of interacting vibrational states. The Interactions identified are of different types; both local and global perturbations are observed. Several new resonance pairs have been found. Together with the well-known anharmonic resonance $(4\nu 50/\nu 30)a$ and Coriolis resonance $(\nu 41/2\nu 50)ab$ these make it possible to build up extensive resonance systems, which allow a conclusive identification of the observed interacting levels and a determination of the involved dark states. Analysis of the spectra of isotopically substituted species of fulminic acid helps confirm the assignments because the substitutions enhance or weaken the interactions identified in the parent species. The assignments of the $2\nu 2,\nu 2+2\nu 3,\nu 1+\nu 3$ and especially of the $2\nu 1$ stretching modes and their hot bands confirm the predicted quasilinear $behaviorc$ of fulminic acid in multiply excited stretching states.