The introduction of narrow width dye lasers and high power electron excitation has enabled lifetime registrations at 0.05 Å FWHM resolution or better which has implied great progress in studies of complex atomic spectra and, in particular, molecular spectra. Thus several thousand optical lifetimes have been measured at high resolution at this laboratory using the High Frequency Deflection technique, which is a refinement of the high power electron excitation delayed-coincidence technique. Besides accurate lifetime and f-value determinations, the technique has been applied to studies of individual spin-orbit and ? components of molecular rotational levels and new properties have been discovered in fundamental molecules. Thus we have established that predissociation and preassociation effects are much more common than was earlier believed. Apart from the increased understanding of basic molecular properties this leads to specific applications, prominent among them being new possibilities of determining accurate dissociation energies and molecular formation rates.