title: Investigation of the excited-state absorption of a Ru dioxolene complex by the Z-scan technique.
abstract: We investigated nonlinear absorption of picosecond laser pulses in a Ru complex [{Ru(bipy)2}2L][PF6] using the open-aperture Z-scan technique. Experiments were performed in a spectral region of moderate linear absorption (lambda=532 nm, sigmag=0.65 x 10(-16) cm(-2)). We observed a transition from reverse saturable absorption to saturable absorption when the excitation intensity was higher than 50 GW/cm2. To determine the population level kinetics, a model based on three- and four-level systems was considered, and the rate equations solved taking into account the propagation equation of the laser pulse inside the sample. Fitting of the experimental data allows extraction of the excited-states absorption cross sections and lifetimes.
authors.affiliation: Department of Physics and Istituto Nazionale per la Fisica della Materia (INFM), University of Bari, Via Amendola 173, 70126 Bari, Italy. cassano@fisica.uniba.it
authors.forename: Tiziana
authors.initials: T
authors.lastname: Cassano
authors.forename: Raffaele
authors.initials: R
authors.lastname: Tommasi
authors.forename: Andrew P
authors.initials: AP
authors.lastname: Meacham
authors.forename: Michael D
authors.initials: MD
authors.lastname: Ward
mesh_terms: D000042:Absorption; D004148:Dioxolanes / Q000737:chemistry*; D007700:Kinetics; D007834:Lasers; D009942:Organometallic Compounds / Q000737:chemistry*; D010777:Photochemistry; D015203:Reproducibility of Results; D017975:Ruthenium Compounds / Q000737:chemistry*; D012680:Sensitivity and Specificity; D013056:Spectrophotometry, Ultraviolet / Q000379:methods*
chemical_list: D004148:Dioxolanes; D009942:Organometallic Compounds; D017975:Ruthenium Compounds