Search results for "Citation"
showing 10 items of 1710 documents
Multilayers of CdSe/CdS/ZnCdS Core/Wings/Shell Nanoplatelets Integrated in a Polymer Waveguide
2017
In this work, fabrication of multilayers of colloidal CdSe/CdS/ZnCdS core/wings/shell nanoplatelets (NPls) on solid substrates by layer-by-layer deposition technology is successfully demonstrated for the first time. Integration of multilayers of nanoplatelets into polymeric waveguide resulted in strong dichroism in absorption and polarization effects in photoluminescence with preferable absorption and emission of TE (horizontal) mode that evidences about in-plane orientation of NPls relative to the planar waveguide. The propagation of the excitation and emission light along the waveguide was thoroughly investigated both theoretically and experimentally for different number of NPl layers.
Polarization holographic recording in Disperse Red1 doped polyurethane polymer film
2011
In this report holographic recording of polarisation and surface relief gratings in Disperse Red 1 (DR1) doped polyurethane polymer films was studied. In this material DR1 is chemically bounded to polyurethane polymer main chain. Polarization holographic recording was performed by two orthogonal circularly polarized 532 nm laser beams. Photoinduced birefringence is a precondition for polarization holograms recording, therefore a detailed study of a photoinduced birefringence and changes of optical properties was performed. The lasers with wavelengths of 375nm, 448nm, 532 nm and 632.8 nm were used as pumping beam for sample excitation. The photoinduced birefringence Δn was measured at 532 nm…
Coherent Electronic Coupling versus Localization in Individual Molecular Dimers
2004
International audience; The electronic excitation transfer and coherent electronic coupling strength were investigated in molecular dimers by spectrally resolved confocal fluorescence spectroscopy. The direct probe of electronic coupling strength distribution was possible due to static disorder in polymer host by single molecule measurements. The dimers with delocalized excitation were also found in comparison to emission originated from localized states. The delocalized and localized state transitions were observed for dimers which were attributed to structural fluctuations of guest-host system.
Multispectral autoflourescence detection of skin neoplasia using steady-state techniques
2019
In the current study were used excitation-emission matrices (EEMs) and synchronous fluorescence spectroscopy (SFS) steady-state techniques in a broad spectral regions (excitation at 220-500 nm and emission at 280-850 nm) to achieve the whole set of endogenous fluorophores, existed in normal and neoplastic cutaneous tissues. Several types of benign, dysplastic and malignant types of skin lesions were investigated ex vivo using both EEM and SFS modalities, namely the basal cell papilloma and carcinoma, pigmented nevi, dysplastic nevi, squamous cell carcinoma and malignant melanoma. Histological analysis was used as a “gold standard” for evaluation of clinical diagnosis of the lesions investig…
Single molecule probing of dynamics in supercooled polymers
2011
6 pages; International audience; Fluorescence experiments with single BODIPY molecules embedded in a poly(methyl acrylate) matrix have been performed at various temperatures in the supercooled regime. By using pulsed excitation, fluorescence lifetime and linear dichroism time trajectories were accessible at the same time. Both observables have been analyzed without data binning. While the linear dichroism solely reflects single particle dynamics, the fluorescence lifetime observable depends on the molecular environment, so that the dynamics from the polymer host surrounding a chromophore contributes to this quantity. We observe that the lifetime correlation decays slightly faster than polar…
Fluorescence excitation and emission spectroscopy on single MEH-PPV chains at low temperature.
2008
Fluorescence emission and excitation spectra of single MEH-PPV polymer molecules dispersed in thin PMMA films have been recorded at 1.2 and 20 K. We observe single as well as multichromophore emission in single chain emission spectra, whereby the relative fractions depend on the two different molecular weights (50 and 350 kDa) studied. The molecular weight also affects the distribution of peak emission maxima, which is monomodal (bimodal) for the low (high) molecular weight. The appearance of an additional "red" subpopulation for the high molecular weight sample is attributed to interactions of multiple chromophores from a sufficiently flexible single chain. The comparison of emission spect…
A theoretical determination of the electronic spectrum of Methylenecyclopropene
1996
The vertical electronic spectrum of methylenecyclopropene, the prototype of the nonalternant hydrocarbons known as fulvenes, has been studied using multiconfigurational second-order perturbation theory. The calculations comprise three valence states and the 3s, 3p, and 3d members of the Rydberg series converging to the first π ionization limit. Vertical excitation energies to three valence states are found at 4.13, 6.12, and 6.82 eV. The second of them corresponds to an excitation from the highest occupied σ orbital to a π* orbital, while the other two are π → π* excitations. The third transition gives rise to the most intense feature in the electronic spectrum. The results are rationalized…
Photodissociation of Formyl Fluoride in Rare Gas Matrixes
2006
Photodissociation of formyl fluoride (HCOF) is studied in Ar, Kr, and Xe matrixes at 248 and 193 nm excitation by following spectral changes in the infrared absorption spectra. In all matrixes, the main photodissociation products are CO/HF species, including CO-HF and OC-HF complexes and thermally unstable CO/HF species (a distorted CO/HF complex or a reaction intermediate), which indicate negligible cage exit of atoms produced via the C-F and C-H bond cleavage channels. However, the observation of traces of H, F, CO, CO(2), F(2)CO, FCO, and HRg(2)(+) (Rg = Kr or Xe) in Kr and Xe matrixes would imply some importance of other reaction channels too. The analysis of the decay curves of the pre…
A coupled cluster calculation of the spectrum of urea
2001
Several coupled cluster methods have been used to compute the vertical excitation energies and oscillator strengths of the lowest singlet states of urea. Except for one excitation, the results are in good agreement with experiment, but previously non-detected transitions have been found.
Low-lying Rydberg states of HCl.
2008
Vertical excitation energies belonging to some different Rydberg series of hydrogen chloride have been determined with a coupled-cluster theoretical approach. These excitation energies have allowed us to calculate electric dipole transition intensities in HCl and allow additional assessment of the calculation approach presently used to provide an adequate description of the valence and Rydberg states of HCl. The molecular quantum defect orbital has been applied to the calculation of oscillator strengths. In particular, new insight is given on the assignment of states as the R1Pi, the 1Delta(4dpi and 5ppi), the 1Sigma+(4dpi), and the nddelta(1Pi, 1Phi) and 4f states.