vorgelegt von

iii The electronic relaxation dynamics of several prototypical aromatic molecules, in-cluding benzene, toluene, xylenes, hexafluorobenzene, pyrrole and selected deriva-tives of pyrrole, were investigated by means of femtosecond time-resolved time-of-flight mass spectrometry (ToF-MS) and femtosecond time-resolved transient pho-toelectron imaging (PEI). These experiments were setup and characterized in this thesis. Benzene molecules were excited to the S1 state by one-photon absorption at λpump = 258 nm and to the S2 state by two-photon absorption at λpump = 387 nm. The excited state decays were monitored by multi-photon ionization, probing with λprobe = 775 nm. Biexponential fits to the transient parent mass signals gave two decay constants, which were respectively, τ1 = 0.04 and τ2> 150 ps for S1 excited benzene and τ1 = 0.02 and τ2> 1.12 ps for S2 excited benzene. Additional infor-mation on the vibronic dynamics were observed by (1+1)- and (3+3)-PEI, where