Dynamics in higher lying excited states: Valence to Rydberg transitions in the relaxation paths of pyrrole and methylated derivatives
(English)Manuscript (preprint) (Other academic)
The involvement of intermediate Rydberg states in the relaxation dynamics of small organic molecules which, after excitation to the valence manifold, also return to the valence manifold, is rarely observed. We report here that such a transiently populated Rydberg state may offer the possibility to modify the outcome of a photochemical reaction. In a time resolved photoelectron study on pyrrole and its methylated derivatives, N-methyl pyrrole and 2,5-dimethyl pyrrole, 6.2 eVphotons (200 nm) are used to excite these molecules into a bright ππ* state. In each case, a π3p-Rydberg state, either the B1(π3py) or the A2(π3pz) state, is populated within 20-50 fs after excitation. The wave packet then proceeds to the lower lyingA2(πσ*) state within a further 20 fs, at which point two competing reaction channels can be accessed: prompt NH (N-CH3) bond cleavage or ring puckering, the latter of which is predicted to require an additional 100 – 160 fs depending on the molecule.
Atom and Molecular Physics and Optics
Research subject Chemical Physics
IdentifiersURN: urn:nbn:se:su:diva-140471OAI: oai:DiVA.org:su-140471DiVA: diva2:1079421