The Experts below are selected from a list of 309 Experts worldwide ranked by ideXlab platform
Anil K. Singh - One of the best experts on this subject based on the ideXlab platform.
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Fluorescence Emission enhancement in substituted 3-styrylindoles in the solid state
Journal of Luminescence, 2010Co-Authors: Abera Asefa, Anil K. SinghAbstract:Fluorescence Emission properties of substituted 3-styrylindoles viz 3-(2-phenylethenyl-E)-NH-indole (1), 3-[2-(4-cyanophenyl)ethenyl-E]-NH-indole (2), and 3-(2-cyano-2-phenylethenyl-Z]-NH-indole (3) in n-hexane, THF-H 2 O binary mixtures and solid state are reported. In general, Fluorescence efficiency in solid state is found to be much higher than in n-hexane solution. The Fluorescence enhancement in solid state is attributed to restricted intramolecular motions. Interestingly, the molecules of 3 in solid state are also bound together through intermolecular hydrogen bonds yielding polymer like structure, leading to further enhancement of Fluorescence Emission. In THF-H 2 O binary mixtures, drastic enhancement of Fluorescence efficiency is observed due to aggregate formation.
Mingxing Jin - One of the best experts on this subject based on the ideXlab platform.
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Laser polarization effect on nitrogen Fluorescence Emission induced by femtosecond filament in air
Journal of Physics: Conference Series, 2017Co-Authors: Anmin Chen, Yuanfei Jiang, Hang Liu, Mingxing JinAbstract:The laser polarization effect on nitrogen Fluorescence Emission induced by femtosecond filament in air is studied. By comparing the femtosecond filament induced Fluorescence Emission under different pump laser polarizations in different focal length cases, the Emission mechanism of nitrogen Fluorescence induced by femtosecond filament is discussed.
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Fluorescence Emission induced by the femtosecond filament transmitting through the butane/air flame.
Spectrochimica acta. Part A Molecular and biomolecular spectroscopy, 2017Co-Authors: Zhe Shi, Anmin Chen, Yuanfei Jiang, Laizhi Sui, Mingxing JinAbstract:We measure the backward Fluorescence spectra generated by the femtosecond filament transmitting through the butane/air flame, and study the Fluorescence Emission from combustion intermediates (CN, CH and C2 radicals), air (mainly N2 and N2+). It is found that the Fluorescence Emission from combustion intermediates, N2 and N2+ shows difference when the femtosecond filament transmits through different parts of the butane/air flame, and we attempt to analyze it in this paper. This study demonstrates that the filament-induced Fluorescence technique can be utilized to sense the combustion intermediates.
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Revisiting the mechanism of nitrogen Fluorescence Emission induced by femtosecond filament in air
Physics of Plasmas, 2017Co-Authors: Yuanfei Jiang, Anmin Chen, Dunli Liu, Mingxing JinAbstract:The backward propagating and side emitted Fluorescence during the femtosecond filamentation in air is experimentally investigated in this paper. By comparing the Fluorescence Emission in the circular and linear polarization states, we find that in the shorter focal length case, the direct ionization of N 2 greatly affects the Fluorescence Emission behaviors: the Fluorescence from N 2 + and N 2 is always stronger in the linear and circular polarization cases, respectively. Based on the observation, the Emission mechanism of nitrogen Fluorescence Emission induced by a femtosecond filament is discussed.
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Influence of laser polarization on plasma Fluorescence Emission during the femtosecond filamentation in air
Optics Communications, 2016Co-Authors: Yan Shi, Anmin Chen, Yuanfei Jiang, Mingxing JinAbstract:Abstract The laser polarization state has a great influence on the plasma Fluorescence Emission during femtoseond filamentation in air. For the spectral lines from N2, in the case of focusing lens with longer focal length (f=100 cm), due to the impact excitation, circular polarization leads to stronger Fluorescence Emission when the laser energy is higher than the ‘energy threshold’ (2.0 mJ). As a lens with shorter focal length (f=40 cm) is used, a similar phenomenon can be observed, however, the ‘energy threshold’ is much lower, which is lower than 0.8 mJ. For the lines from N 2 + , especially for the 391 nm one, their Emission is stronger in the linear polarization state. The mechanism of plasma Fluorescence Emission during femtosecond filamentation is discussed based on the analysis of these phenomena, which will be helpful to the remote sensing and spectrum analysis.
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Research on the Fluorescence Emission from water vapor induced by femtosecond filamentation in air
Chemical Physics Letters, 2016Co-Authors: Yuanfei Jiang, Anmin Chen, Mingxing JinAbstract:Abstract Our experiments show that initial energy and humidity strongly influences the water vapor Fluorescence induced by ultrashort intense femtosecond laser pulses. It is found that the Fluorescence signal can be enhanced by both increasing the humidity in the case of fixed energy and increasing the pulse energy in the case of fixed humidity. In addition, water vapor Fluorescence Emission in the linear polarization is stronger than that in the circular polarization due to the higher dissociation efficiency of linearly polarized pulses. The mechanism of water vapor Fluorescence Emission during femtosecond filamentation is discussed based on the analysis of these phenomena.
Sethuraman Sankararaman - One of the best experts on this subject based on the ideXlab platform.
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donor acceptor substituted phenylethynyltriphenylenes excited state intramolecular charge transfer solvatochromic absorption and Fluorescence Emission
Beilstein Journal of Organic Chemistry, 2010Co-Authors: Ritesh Nandy, Sethuraman SankararamanAbstract:Several 2-(phenylethynyl)triphenylene derivatives bearing electron donor and acceptor substituents on the phenyl rings have been synthesized. The absorption and Fluorescence Emission properties of these molecules have been studied in solvents of different polarity. For a given derivative, solvent polarity had minimal effect on the absorption maxima. However, for a given solvent the absorption maxima red shifted with increasing conjugation of the substituent. The Fluorescence Emission of these derivatives was very sensitive to solvent polarity. In the presence of strongly electron withdrawing (–CN) and strongly electron donating (–NMe2) substituents large Stokes shifts (up to 130 nm, 7828 cm−1) were observed in DMSO. In the presence of carbonyl substituents (–COMe and –COPh), the largest Stokes shift (140 nm, 8163 cm−1) was observed in ethanol. Linear correlation was observed for the Stokes shifts in a Lippert–Mataga plot. Linear correlation of Stokes shift was also observed with ET(30) scale for protic and aprotic solvents but with different slopes. These results indicate that the Fluorescence Emission arises from excited state intramolecular charge transfer in these molecules where the triphenylene chromophore acts either as a donor or as an acceptor depending upon the nature of the substituent on the phenyl ring. HOMO–LUMO energy gaps have been estimated from the electrochemical and spectral data for these derivatives. The HOMO and LUMO surfaces were obtained from DFT calculations.
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Synthesis, Absorption, and Fluorescence‐Emission Properties of 1,3,6,8‐Tetraethynylpyrene and Its Derivatives
European Journal of Organic Chemistry, 2005Co-Authors: Gandikota Venkataramana, Sethuraman SankararamanAbstract:The synthesis of several 1,3,6,8-tetraethynylpyrene derivatives is reported. The effect of extended acetylenic conjugation on their absorption and Fluorescence-Emission properties is studied. Significant bathochromic shifts of both the absorption and Fluorescence Emission bands are observed. These derivatives emit Fluorescence in the visible (400–550 nm) region. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Abera Asefa - One of the best experts on this subject based on the ideXlab platform.
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Fluorescence Emission enhancement in substituted 3-styrylindoles in the solid state
Journal of Luminescence, 2010Co-Authors: Abera Asefa, Anil K. SinghAbstract:Fluorescence Emission properties of substituted 3-styrylindoles viz 3-(2-phenylethenyl-E)-NH-indole (1), 3-[2-(4-cyanophenyl)ethenyl-E]-NH-indole (2), and 3-(2-cyano-2-phenylethenyl-Z]-NH-indole (3) in n-hexane, THF-H 2 O binary mixtures and solid state are reported. In general, Fluorescence efficiency in solid state is found to be much higher than in n-hexane solution. The Fluorescence enhancement in solid state is attributed to restricted intramolecular motions. Interestingly, the molecules of 3 in solid state are also bound together through intermolecular hydrogen bonds yielding polymer like structure, leading to further enhancement of Fluorescence Emission. In THF-H 2 O binary mixtures, drastic enhancement of Fluorescence efficiency is observed due to aggregate formation.
Yuanfei Jiang - One of the best experts on this subject based on the ideXlab platform.
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Laser polarization effect on nitrogen Fluorescence Emission induced by femtosecond filament in air
Journal of Physics: Conference Series, 2017Co-Authors: Anmin Chen, Yuanfei Jiang, Hang Liu, Mingxing JinAbstract:The laser polarization effect on nitrogen Fluorescence Emission induced by femtosecond filament in air is studied. By comparing the femtosecond filament induced Fluorescence Emission under different pump laser polarizations in different focal length cases, the Emission mechanism of nitrogen Fluorescence induced by femtosecond filament is discussed.
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Fluorescence Emission induced by the femtosecond filament transmitting through the butane/air flame.
Spectrochimica acta. Part A Molecular and biomolecular spectroscopy, 2017Co-Authors: Zhe Shi, Anmin Chen, Yuanfei Jiang, Laizhi Sui, Mingxing JinAbstract:We measure the backward Fluorescence spectra generated by the femtosecond filament transmitting through the butane/air flame, and study the Fluorescence Emission from combustion intermediates (CN, CH and C2 radicals), air (mainly N2 and N2+). It is found that the Fluorescence Emission from combustion intermediates, N2 and N2+ shows difference when the femtosecond filament transmits through different parts of the butane/air flame, and we attempt to analyze it in this paper. This study demonstrates that the filament-induced Fluorescence technique can be utilized to sense the combustion intermediates.
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Revisiting the mechanism of nitrogen Fluorescence Emission induced by femtosecond filament in air
Physics of Plasmas, 2017Co-Authors: Yuanfei Jiang, Anmin Chen, Dunli Liu, Mingxing JinAbstract:The backward propagating and side emitted Fluorescence during the femtosecond filamentation in air is experimentally investigated in this paper. By comparing the Fluorescence Emission in the circular and linear polarization states, we find that in the shorter focal length case, the direct ionization of N 2 greatly affects the Fluorescence Emission behaviors: the Fluorescence from N 2 + and N 2 is always stronger in the linear and circular polarization cases, respectively. Based on the observation, the Emission mechanism of nitrogen Fluorescence Emission induced by a femtosecond filament is discussed.
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Influence of laser polarization on plasma Fluorescence Emission during the femtosecond filamentation in air
Optics Communications, 2016Co-Authors: Yan Shi, Anmin Chen, Yuanfei Jiang, Mingxing JinAbstract:Abstract The laser polarization state has a great influence on the plasma Fluorescence Emission during femtoseond filamentation in air. For the spectral lines from N2, in the case of focusing lens with longer focal length (f=100 cm), due to the impact excitation, circular polarization leads to stronger Fluorescence Emission when the laser energy is higher than the ‘energy threshold’ (2.0 mJ). As a lens with shorter focal length (f=40 cm) is used, a similar phenomenon can be observed, however, the ‘energy threshold’ is much lower, which is lower than 0.8 mJ. For the lines from N 2 + , especially for the 391 nm one, their Emission is stronger in the linear polarization state. The mechanism of plasma Fluorescence Emission during femtosecond filamentation is discussed based on the analysis of these phenomena, which will be helpful to the remote sensing and spectrum analysis.
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Research on the Fluorescence Emission from water vapor induced by femtosecond filamentation in air
Chemical Physics Letters, 2016Co-Authors: Yuanfei Jiang, Anmin Chen, Mingxing JinAbstract:Abstract Our experiments show that initial energy and humidity strongly influences the water vapor Fluorescence induced by ultrashort intense femtosecond laser pulses. It is found that the Fluorescence signal can be enhanced by both increasing the humidity in the case of fixed energy and increasing the pulse energy in the case of fixed humidity. In addition, water vapor Fluorescence Emission in the linear polarization is stronger than that in the circular polarization due to the higher dissociation efficiency of linearly polarized pulses. The mechanism of water vapor Fluorescence Emission during femtosecond filamentation is discussed based on the analysis of these phenomena.