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Anni M. Photodegradation Effects on the Emission Properties of an Amplifying Poly(9,9-dioctylfluorene) Active Waveguide Operating in Air. J Phys Chem B 2012; 116:4655-60. [DOI: 10.1021/jp212529d] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- M. Anni
- Dipartimento di Matematica
e Fisica ”Ennio De
Giorgi”, Università del Salento, Via per Arnesano, 73100 Lecce, Italy
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Anni M, Gigli G, Zavelani-Rossi M, Gadermaier C, Lanzani G, Barbarella G, Favaretto L, Cingolani R. Tunable Optical Gain from Soluble Thiophene-Based Oligomers. ACTA ACUST UNITED AC 2011. [DOI: 10.1557/proc-665-c1.5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
ABSTRACTTunable optical gain is demonstrated, through pump and probe measurements, in spin coated neat films of soluble S,S-dioxide oligothiophenes with different functionalization pattern. The molecular functionalization with alkyl and aryl groups allows us to obtain photoluminescence efficiency up to 70%, good chemical stability, high solubility and tunable gain along the visible range from 470 nm to 660 nm. The gain cross section is up to 9*10-18 cm2. The gain relaxation dynamic is studied through time resolved pump and probe measurements. A comparison with some of the best organic materials for laser application is presented. From these results we conclude that thienyl-S,S-dioxide oligothiophenes are interesting materials for applications to organic lasers and amplifiers.
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Anni M, Alemanno E, Cretí A, Ingrosso C, Panniello A, Striccoli M, Curri ML, Lomascolo M. Interplay between amplified spontaneous emission, Forster resonant energy transfer, and self-absorption in hybrid poly(9,9-dioctylfluorene)-CdSe/ZnS nanocrystal thin films. J Phys Chem A 2010; 114:2086-90. [PMID: 20085251 DOI: 10.1021/jp906860c] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We investigated the excitation density dependence of the photoluminescence spectra of hybrid poly(9,9-dioctylfluorene)-CdSe/ZnS nanocrystals (PF8-NCs) thin films. We demonstrate that this experiment allows the determination of the efficiency of all the CdSe/ZnS NCs excitation processes and that the presence of amplified spontaneous emission (ASE) from the PF8 leads to a strong dependence of the NC excitation processes from the laser excitation density. Below the PF8 ASE threshold only about 6% of the excitons in the NCs are due to pump laser absorption, while about 94% of the NC excitation is due to the interaction with the PF8, and it is due for about 58% to PF8-->NC Forster resonant energy transfer (FRET) and for about 37% to reabsorption by the NCs of the PF8 luminescence. The presence of PF8 ASE significantly modifies this scenario by strongly decreasing the FRET importance and strongly increasing the reabsorption one. The interplay between reduced FRET and increased reabsorption overall decreases the NC excitation due to PF8 indicating that ASE from the donors should be avoided if efficient NCs excitation under strong pumping is wished.
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Affiliation(s)
- M Anni
- Dipartimento di Ingegneria dell'Innovazione, Università del Salento, Via per Monteroni, 73100 Lecce, Italy.
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Anni M, Rella R. Oxygen Optical Gas Sensing by Reversible Fluorescence Quenching in Photo-Oxidized Poly(9,9-dioctylfluorene) Thin Films. J Phys Chem B 2009; 114:1559-61. [DOI: 10.1021/jp9062143] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- M. Anni
- Dipartimento di Ingegneria dell’Innovazione, Università del Salento, Via per Monteroni, 73100 Lecce, Italy, and Istituto per la Microelettronica e Microsistemi, (IMM)-CNR, Via per Monteroni, I-73100 Lecce, Italy
| | - R. Rella
- Dipartimento di Ingegneria dell’Innovazione, Università del Salento, Via per Monteroni, 73100 Lecce, Italy, and Istituto per la Microelettronica e Microsistemi, (IMM)-CNR, Via per Monteroni, I-73100 Lecce, Italy
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Cretì A, Anni M, Zavelani-Rossi M, Lanzani G, Manna L, Lomascolo M. Ultrafast carrier dynamics and confined acoustic phonons in CdSe nanorods. ACTA ACUST UNITED AC 2008. [DOI: 10.1088/1464-4258/10/6/064004] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Fabiano E, Della Sala F, Barbarella G, Lattante S, Anni M, Sotgiu G, Hättig C, Cingolani R, Gigli G. Optical Properties of N-Succinimidyl Bithiophene and the Effects of the Binding to Biomolecules: Comparison between Coupled-Cluster and Time-Dependent Density Functional Theory Calculations and Experiments. J Phys Chem B 2006; 110:18651-60. [PMID: 16970495 DOI: 10.1021/jp062890w] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We report a joint theoretical-experimental study on the optical properties of 5-N-succinimidyl-2,2'-bithiophene (NS-2T), a prototype system for a new class of biomarkers. Time-dependent density functional theory (TD-DFT) and approximate coupled-cluster single and doubles (CC2) calculations are performed in the ground and excited states. Theoretical results are compared with absorption, photoluminescence (PL), time-resolved PL, and PL quantum efficiency measurements. The excited state of NS-2T has a larger dipole moment as compared to that of the ground state, explaining the experimental shift of the PL peak in solvents of different polarity, and a smaller intersystem crossing (ISC) rate as compared to that of isolated bithiophene (2T), explaining the increased PL quantum efficiency. We also studied two model systems to describe the effects of the covalent binding of NS-2T to biomolecules and proteins with the epsilon-NH(2) lysine groups. These model systems show optical properties closer to 2T, as the PL quantum efficiency is reduced due to the increased ISC rate. Theoretical calculations and experimental results show that covalent binding of NS-2T to a biomolecule will blue-shift the absorption but not the photoluminescence. CC2 and TD-DFT can very well describe the absorption and photoluminescence energies of all three systems, but the presence of several charge-transfer transitions in the TD-DFT spectrum of NS-2T required the use of a correlated method to validate the TD-DFT results.
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Affiliation(s)
- E Fabiano
- National Nanotechnology Laboratory of INFM-CNR, Distretto Tecnologico, Università degli Studi di Lecce, Via per Arnesano, I-73100 Lecce, Italy
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Anni M, Caruso ME, Lattante S, Cingolani R. The role of excitons’ quasiequilibrium in the temperature dependence of the poly(9,9-dioctylfluorene) β phase photoluminescence. J Chem Phys 2006; 124:134707. [PMID: 16613468 DOI: 10.1063/1.2179795] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We investigated the temperature dependence of the poly(9,9-dioctylfluorene) beta phase photoluminescence (PL) spectra in spin coated thin films from tetrahydrofuran solutions. As the temperature increases from 18 to 300 K a continuous blueshift of the 0-0 PL peak of about 25 meV and an increase of the peak full width at half maximum (FWHM) of about 49 meV are observed. We show that the PL spectra temperature dependence is not due to a temperature dependent average conjugation length, as often assumed, but instead it can be quantitatively explained in the frame of a thermal quasiequilibrium model for excitons in an inhomogeneously broadened excited states distribution. We demonstrate that the emission blueshift and broadening are mainly due to the increase of the excitons' temperature with the sample one. This effect is partially compensated by an increasing efficiency of the exciton energy migration. The interplay between these two processes quantitatively explains the observed temperature dependence of the PL peak energy and of its FWHM. On the contrary we show that the PL spectra are almost independent of the absorption blueshift with temperature.
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Affiliation(s)
- M Anni
- National Nanotechnology Laboratory of CNR-INFM, Dipartimento di Ingegneria dell'Innovazione, Università degli Studi di Lecce, Via per Arnesano, 73100 Lecce, Italy.
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Anni M, Della Sala F, Raganato MF, Fabiano E, Lattante S, Cingolani R, Gigli G, Barbarella G, Favaretto L, Görling A. Nonradiative Relaxation in Thiophene-S,S-dioxide Derivatives: The Role of the Environment. J Phys Chem B 2005; 109:6004-11. [PMID: 16851655 DOI: 10.1021/jp046465j] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The intramolecular radiative and nonradiative relaxation processes of three thiophene-S,S-dioxide derivatives with different molecular rigidity are investigated in different solutions and in inert matrix. We show that the fluorescence quantum efficiency and the relaxation dynamics are strongly dependent on the environment viscosity, whereas they are almost independent of the environment polarity. We demonstrate that this strong dependence is due to an environment dependent nonradiative decay rate, whereas no relevant variations of the radiative decay rate are observed. We demonstrate that the dipole coupling with the solvent does not provide an efficient nonradiative decay channel and that the S(n) - S(1) vibrational relaxation is very efficient in all of the molecules and for all of the investigated environments. Moreover first-principles time-dependent density-functional theory calculations in the correct, i.e., excited-state, molecular conformation, suggest that significant contributions of intersystem crossing to the triplet manifold can be excluded. We then conclude that the main nonradiative process determining the fluorescence quantum efficiency of this class of molecules is S(1) - S(0) internal conversion (IC). An explanation for the IC rate dependence in terms of the environment viscosity, molecular rigidity, S(1) - S(0) energy-gap, and molecular volume is presented.
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Affiliation(s)
- M Anni
- National Nanotechnology Laboratory (NNL) of INFM, Dipartimento di Ingegneria dell'Innovazione, Università degli Studi di Lecce, Via per Arnesano, 73100 Lecce, Italy
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Raganato MF, Vitale V, Della Sala F, Anni M, Cingolani R, Gigli G, Favaretto L, Barbarella G, Weimer M, Görling A. The effects of oxygenation on the optical properties of dimethyl-dithienothiophenes: Comparison between experiments and first-principles calculations. J Chem Phys 2004; 121:3784-91. [PMID: 15303947 DOI: 10.1063/1.1775782] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Modifications of the optical properties of dimethyl-dithienothiophenes due to the oxygen functionalization of the central sulfur atom are investigated. We have measured the absorption, photoluminescence (PL) and PL excitation spectra, the PL quantum efficiencies, and the PL decay times. These experimental results are interpreted and compared with first-principles time-dependent density-functional theory calculations, which predict, for the considered systems, excitation and emission energies with an accuracy of 0.1 eV. It is found that the oxygenation strongly changes optical and photophysical properties. These effects are related to the modifications of the energetically lowest-unoccupied molecular orbital and the energetically second highest occupied one, which change the relative position of the two lowest singlet and triplet excited states.
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Affiliation(s)
- M F Raganato
- National Nanotechnology Laboratory of INFM, Distretto Tecnologico, Universita degli Studi di Lecce, Via per Arnesano, I-73100 Lecce, Italy
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Müller JG, Lemmer U, Raschke G, Anni M, Scherf U, Lupton JM, Feldmann J. Linewidth-limited energy transfer in single conjugated polymer molecules. Phys Rev Lett 2003; 91:267403. [PMID: 14754089 DOI: 10.1103/physrevlett.91.267403] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2003] [Indexed: 05/24/2023]
Abstract
Using low temperature single molecule spectroscopy on rigid-rod conjugated polymers we are able to identify homogeneously broadened, strongly polarized emission from individual chromophore units on a single chain. Gated fluorescence spectroscopy allows real time imaging of intramolecular energy transfer as the chain behaves as a series of weakly interacting chromophores. Energy transfer is controlled by the chromophoric spectral linewidth, which depends on temperature. Linewidths exceeding intramolecular disorder lead to incoherent chromophore coupling and collective fluorescence phenomena.
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Affiliation(s)
- J G Müller
- Photonics and Optoelectronics Group, Physics Department and CeNS, University of Munich, 80799 Munich, Germany
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Gigli G, Lomascolo M, Anni M, Barbarella G, Lugli P, Cingolani R. Photoluminescence Efficiency of Substituted Quaterthiophene Crystals. Phys Rev Lett 2001; 86:167-170. [PMID: 11136120 DOI: 10.1103/physrevlett.86.167] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/27/1999] [Indexed: 05/23/2023]
Abstract
The photoluminescence (PL) efficiency of substituted alpha-conjugated quaterthiophene crystals shows marked differences depending on crystal packing and molecular geometry. This effect is studied by evaluating the role of the intermolecular interactions and the effects of the single molecule conformation on the intersystem crossing (ISC) rate. The comparison of these calculations with absolute quantum efficiency measurements and with the experimental temperature dependence of the PL decay time, indicates that the differences in PL efficiency are not inherent to crystal packing effects but they are determined by the ISC rate.
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Affiliation(s)
- G Gigli
- Istituto Nazionale di Fisica della Materia, Dipartimento di Ingegneria dell'Innovazione, Università di Lecce, Via Arnesano, 73100 Lecce, Italy
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Vasanelli A, Rinaldi R, Anni M, Lomascolo M, Antonaci S, Passaseo A, Cingolani R, Taurino A, Catalano M. Correlation between shape and electronic states in nanostructures. Micron 2000; 31:245-51. [PMID: 10702973 DOI: 10.1016/s0968-4328(99)00090-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
We show how the electronic states of quantum wires and quantum dots can be evaluated exactly starting from the profile of the nanostructure observed by transmission electron microscopy, scanning tunneling microscopy and atomic force microscopy. The calculated quantization energies reproduce the energy position of the luminescence resonances in the optical spectra of different samples, without fitting parameters.
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Cocco P, Salis S, Anni M, Cocco ME, Flore C, Ibba A. Effects of short-term occupational exposure to lead on erythrocyte glucose-6-phosphate dehydrogenase activity and serum cholesterol. J Appl Toxicol 1995; 15:375-8. [PMID: 8666720 DOI: 10.1002/jat.2550150506] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The effect of short-term occupational exposure to lead on erythrocyte glucose-6-phosphate dehydrogenase (G6PD) activity and serum cholesterol was studied in 40 male workers of a lead and zinc foundry. All parameters were measured just before employment and after 172 +/- 21.3 days of work. Genetic deficiency of erythrocyte G6PD was observed in 5/40 subjects. Among G6PD normal subjects, increases in enzyme activity followed any change (increase or decrease) in blood lead. At the pre-employment test, serum cholesterol parameters did not show any correlation with GOD activity or blood lead, and they were not affected by exposure. Cholesterol values observed among all the GOD-deficient subjects were within the range of the rest of the study population.
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Affiliation(s)
- P Cocco
- Istituto di Medicina del Lavoro, Università di Cagliari, Italy
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Anni M. Dermatomyositis. Arch Dermatol Res 1961. [DOI: 10.1007/bf00588937] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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