Mode dependence of the state-to-state vibrational dynamics of HCN–HF Original Research Article

The vibrational predissociation dynamics of HCN–HF have been studied at the state-to-state level by recording photofragment angular distributions resulting from excitation of both the C–H and H–F stretching vibrations. The results obtained from a combination of a parent molecule orientation technique and photofragment probe laser experiments show that most of the excess energy is found in rotational energy of the HF fragment. Nevertheless, in contrast with other systems studied to date, HCN–HF is very unusual in that a significant fraction of the available energy appears in the form of recoil kinetic energy (∼40%). The dissociation energy of the complex is also determined to be 1970±10 cm−1.