title: Three- and four-photon absorption of a multiphoton absorbing fluorescent probe.
abstract: High-order multiphoton excitation processes are becoming a reality for fluorescence imaging and phototherapy treatment because they afford minimization of scattered light losses and a reduction of unwanted linear absorption in the living organism transparency window, making them less susceptible to photodamage, while improving the irradiation penetration depth and spatial resolution. We report the four-photon-excited fluorescence emission of (7-benzothiazol-2-yl-9,-didecylfluoren-2-yl)diphenylamine in hexane and its four-photon absorption cross section sigma4' = 8.1 x 10(-109) cm8 s3 photon(-3) for the transition S0 --> S1 when excited at 1600 nm with a tunable optical parametric generator (OPG) pumped by picosecond laser pulses. When pumped at 1200 nm, three-photon absorption was observed, corresponding to the same transition.
authors.affiliation: Department of Chemistry and School of Optics/Center for Research and Education in Optics and Lasers/Florida Photonics Center of Excellence, University of Central Florida, Orlando, Florida 32816-2366, USA. florenzi@mail.ucf.edu
authors.forename: Florencio E
authors.initials: FE
authors.lastname: Hernández
authors.forename: Kevin D
authors.initials: KD
authors.lastname: Belfield
authors.forename: Ion
authors.initials: I
authors.lastname: Cohanoschi
authors.forename: Mihaela
authors.initials: M
authors.lastname: Balu
authors.forename: Katherine J
authors.initials: KJ
authors.lastname: Schafer
mesh_terms: D052160:Benzothiazoles; D004307:Dose-Response Relationship, Radiation; D005449:Fluorenes / Q000528:radiation effects*; D031541:Fluorescence Resonance Energy Transfer / Q000379:methods*; D005456:Fluorescent Dyes / Q000138:chemical synthesis* / Q000528:radiation effects*; D007834:Lasers; D036641:Microscopy, Fluorescence, Multiphoton / Q000379:methods*; D013844:Thiazoles / Q000528:radiation effects*
chemical_list: C495493:(7-benzothiazol-2-yl-9,-didecylfluoren-2-yl)diphenylamine; D052160:Benzothiazoles; D005449:Fluorenes; D005456:Fluorescent Dyes; D013844:Thiazoles