Knowledge Bank

Absorption spectra of short-lived excited states of molecules are measured using single picosecond pulses from a Nd:glass laser, coupled with a photographic spectrometer. The time resolution (6-8 ps) and wide range of wavelengths covered by the spectrometer (400--900 nm) allows us to identify excited states, and to measure their kinetic behavior. The time-resolved absorption spectra of quinoxaline and s-tetraxine, in their excited singlet states, are measured. Their rate of decay will be compared with the rate of decay of their fluorescent emission, also measured using a picosecond laser. The time-resolved measurement of the intersystem crossing of a11-t-retinal from its first excited state to its triplet state will also be presented.