Picosecond double-beam absorption spectrometer

Apparatus was constructed for investigating fast photophysical and photochemical processes resulting from selective excitation of vibronic molecular states. A single laser pulse emitted from a YAG:Nd mode-locked laser was amplified in a two-stage amplifier, frequency converted in a parametric oscillator, and used to excite molecules. A pulse of the continuum was used as the test pulse. A time resolution of ± 3 psec and a precision of ± 3×10^–3 optical density units were attained in the absorption measurements carried out in a study of primary processes of conversion of the energy of light in photosynthetic reaction centers.