title: Femtosecond Excited State Dynamics of Size Selected Neutral Molecular Clusters.
abstract: The work describes a novel experimental approach to track the relaxation dynamics of an electronically excited distribution of neutral molecular clusters formed in a supersonic expansion, by pump-probe femtosecond ionization. The introduced method overcomes fragmentation issues and makes possible to retrieve the dynamical signature of a particular cluster from each mass channel, by associating it to an IR transition of the targeted structure. We have applied the technique to study the nonadiabatic relaxation of pyrrole homoclusters. The results obtained exciting at 243 nm, near the origin of the bare pyrrole electronic absorption, allow us to identify the dynamical signature of the dimer (Py)2, which exhibits a distinctive lifetime of τ1 ∼ 270 fs, considerably longer than the decays recorded for the monomer and bigger size clusters (Py)n>2. A possible relationship between the measured lifetime and the clusters geometries is tentatively discussed.
authors.affiliation: SGIker Laser Facility, UPV/EHU , Sarriena, s/n, 48940 Leioa, Spain.
authors.forename: Raúl
authors.initials: R
authors.lastname: Montero
authors.affiliation: Departamento de Química Física, Universidad del País Vasco (UPV/EHU) , Apartment 644, 48080 Bilbao, Spain.
authors.forename: Iker
authors.initials: I
authors.lastname: León
authors.affiliation: Departamento de Química Física, Universidad del País Vasco (UPV/EHU) , Apartment 644, 48080 Bilbao, Spain.
authors.forename: José A
authors.initials: JA
authors.lastname: Fernández
authors.affiliation: Departamento de Química Física, Universidad del País Vasco (UPV/EHU) , Apartment 644, 48080 Bilbao, Spain.
authors.forename: Asier
authors.initials: A
authors.lastname: Longarte