Helios is a transient absorption spectrometer unveiled by Newport Corp. for the study of ultrafast phenomena such as electronic deactivation, intersystem crossing, vibrational relaxation, internal conversion and intramolecular electron transfer. The turnkey pump-probe system offers an experimental time window of 150 fs to 3.2 ns over the wavelength range of 350 to 1600 nm. The unit contains the optics, optomechanics, the delay line and the spectrometer. Also included is a PC with data acquisition hardware and software. The system works with a Ti:sapphire femtosecond laser to capture the spectral and kinetic data required for investigating photoexcitation events on subpicosecond and longer time-scales.