Although the transfer of an electron from a donor to an acceptor after one of them has been electronically excited by the absorption of light appears to be a very simple reaction, there are still many open questions concerning the detailed mechanism of photoinduced electron transfer. It is nevertheless a fascinating and very important reaction, given its key importance in photosynthesis and many modern approaches to solar energy conversion. The objective of this PhD thesis was thus to use ultrafast, femtosecond-resolved spectroscopy in order to gain a better insight to photoinduced electron transfer occuring for closed-shell organic molecules in liquid solution, in particular where the relative geometry of the reaction partners is concerned. The investigations span a large variety of electron donor-acceptor systems, ranging from the intramolecular to the bimolecular case and from simple model systems to complex architectures with potential apllications in solar energy coversion.