Cl3− electron photodetachment spectrum: measurement and assignment

An electron photodetachment spectrum of Cl3− is reported for 193 nm (6.42 eV) excitation. The spectrum was assigned using high-level ab initio calculation for the Cl3 radical and the Cl3− ion. A broad band centered around 1.25 eV (electron kinetic energy) has been assigned to the Cl3−(X 1Σg+)→Cl3(X 2Πu) and Cl3(1 2Σg+) transitions. Vertical photodetachment accesses the transition state region for the Cl exchange reaction: Cl+Cl2→Cl2+Cl. A narrow doublet band at 0.55 eV is assigned to the Cl3−(X 1Σg+)→Cl3(1 2Πg) transition, split by spin–orbit interaction.