Knowledge Bank

The C-H stretching fundamental of HCCN has been observed under high resolution. This transient molecule was produced by the flash photolysis of dibromoacetonitrile ($Br2$HCCN) at 193 nm and its spectrum probed using a color center laser. Rotational analysis of the $\nu 1$ fundamental places its origin at $3246.657cm-1$. Several hot bands associated with the bending vibrations have been observed and two, $\nu 1+\nu 5-\nu 5$ and $\nu 1+\nu 4-\nu 4$, have been rotationally analyzed. The energy of the $\nu 5$ band was obtained by measuring the intensity of the $\nu 1+\nu 5-\nu 5$ band relative to the fundamental, assuming a Boltzmann distribution. A comparison of this energy with that of quasilinear fulminic acid, HCNO, suggests a similar floppy HCX bending potential.