Photodissociation dynamics of the I2− anion using femtosecond photoelectron spectroscopy

The photodissociation dynamics of the I2− anion have been studied in real-time using femtosecond photoelectron spectroscopy. In this experiment, I2− is excited to a dissociative electronic state with an ultrafast pump pulse, and the photoelectron spectrum of the dissociating anion is measured by photodetachment with a second, ultrafast probe pulse. The variation of the photoelectron spectrum with delay time enables one to monitor the dissociating anion from the initial Franck-Condon region of excitation out to the asymptotic region. Dissociation occurs on a time scale of 100 fs. The results are compared with quantum mechanical simulations using previously published potential energy curves for I2−.