title: Superfluorescent squaraine with efficient two-photon absorption and high photostability.
abstract: The synthesis, linear photophysical, two-photon absorption (2PA), femtosecond transient absorption, and superfluorescence properties of a new symmetrical squaraine derivative (1) are reported. Steady-state linear spectral and photochemical properties, fluorescence lifetimes, and excitation anisotropy of 1 were investigated in various organic solvents. High fluorescence quantum yields (≈0.7) and very high photostability (photodecomposition quantum yields ≈10(-6)-10(-8)) were observed. An open-aperture Z-scan method was used to obtain 2PA spectra of 1 over a broad spectral range (maximum 2PA cross section ≈1000 GM). Excited-state absorption (ESA) and gain was observed by femtosecond transient absorption spectroscopy, in which both reached a maximum at approximately 500 fs. Squaraine 1 exhibits efficient superfluorescence. The quantum chemical study of 1 revealed the simulated vibronic nature of the 1PA and 2PA spectra were in good agreement with experimental data; this may provide the ability to predict potential advanced photonic materials.
authors.affiliation: Department of Chemistry, University of Central Florida, P.O. Box 162366, Orlando, FL 32816-2366 (USA); CREOL, The College of Optics and Photonics, University of Central Florida, P.O. Box 162366, Orlando, FL 32816-2366 (USA). belfield@ucf.edu.
authors.forename: Kevin D
authors.initials: KD
authors.lastname: Belfield
authors.forename: Mykhailo V
authors.initials: MV
authors.lastname: Bondar
authors.forename: Hafeez S
authors.initials: HS
authors.lastname: Haniff
authors.forename: Ivan A
authors.initials: IA
authors.lastname: Mikhailov
authors.forename: Gheorghe
authors.initials: G
authors.lastname: Luchita
authors.forename: Olga V
authors.initials: OV
authors.lastname: Przhonska
mesh_terms: D000042:Absorption; D000627:Aminophenols / Q000138:chemical synthesis / Q000737:chemistry*; D003503:Cyclobutanes / Q000138:chemical synthesis / Q000737:chemistry*; D005456:Fluorescent Dyes / Q000737:chemistry; D006860:Hydrogen Bonding; D008027:Light; D010636:Phenols / Q000737:chemistry*; D017785:Photons; D011789:Quantum Theory; D013050:Spectrometry, Fluorescence
chemical_list: D000627:Aminophenols; D003503:Cyclobutanes; D005456:Fluorescent Dyes; D010636:Phenols; C480596:squaraine
keywords: density functional calculations; donor-acceptor systems; fluorescence; hydrogen bonds; photochemistry