Transient Absorption
The UV/VIS-absorption-spectra of excited states differ considerably from those of ground states. Thus, recording changes of the spectrum induced by photo-excitation may yield data such as lifetimes of excited states, their character (e.g. singlet or triplet) as well as the formation of photo-products. Relying on a femtosecond laser/amplifier system (Coherent Libra, 1kHz, ~100 fs, 800 nm) we generate light pulses for excitation (actinic pump) by means of non-linear optics (SHG = 400 nm, THG = 266 nm and SHG of TOPAS output = 250 – 370 nm). White light pulses, which are generated in a CaF2 plate, serve for broadband probing (300 nm up to 780 nm). The whole spectrum can be recorded simultaneously thanks to a spectrograph and diode array.
