Knowledge Bank

Photofragment angular distributions have been obtained for the HF-HCl complex and its isomer HCL-HF, resulting from vibrational predissociation induced by F-center laser excitation. A complete assignment of the vibrational and rotational states of the fragments has been obtained by orienting the complex in a large DC electric field and probing the fragment internal states using a second F-center laser. Dissociation of the HF-HCl complex, following vibrational excitation of the "free" HF stretch, leads to the production of a v=1 HCl fragment. For the HCl-HF isomer this V-V channel appears to be blocked, leading to the production of HCl in v=0. This behavior can be understood in terms of the blocking effect of the heavy chlorine atom. The remarkable changes in linewidths in the photodissociation of both $isomer1$ will be discussed.