266 nm Photolysis of HOCl and DOCl: laser-excitation fluorescence detection of OH and OD

Abstract

Fragment rotational population distributions for OH and OD were observed by laser-excitation fluorescence following the 266 nm photolysis in a free jet molecular beam of HOCl and DOCl, respectively. The photodissociation dynamics show a strong preference for the ²Π(A′) OH or OD lambda doublet component in both spin–orbit states. The ²Π_3/2 state is more populated than the ²Π_1/2 state of OH. The distributions are consistent with photolysis via a repulsive excited state and the measured rotational alignment (–0.28) is compatible with an excited-state symmetry of A′ for the dominant dissociation pathway. The high-J limiting value for the degree of electron alignment reaches the extreme value of –1 for the ²Π_1/2 state for both OH and OD, but falls short of this for the ²Π_3/2 state, reaching only –0.7.