Intermolecular photoinduced electron transfer between C-60 and two bis-diphenylamino (diphenylpolyenes) in dilute solutions was measured using step-scan Fourier transform spectroscopy which yielded extremely smooth temporal data. A mechanistic model containing a single intermediate and treatment of the kinetics generates a total quantum efficiency for free ions that can be factored into two terms, a quenching efficiency, Phi (Q), and an efficiency for formation of free ions out of the intermediate, Phi (S1). Two methods for extracting Phi (S1) are provided and the dependence on solvent polarity and other parameters is investigated.