The Experts below are selected from a list of 315 Experts worldwide ranked by ideXlab platform
Jianping Wang - One of the best experts on this subject based on the ideXlab platform.
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efficient vibrational energy transfer through Covalent Bond in indigo carmine revealed by nonlinear ir spectroscopy
Journal of Physical Chemistry B, 2017Co-Authors: Xuemei He, Pengyun Yu, Juan Zhao, Jianping WangAbstract:Ultrafast vibrational relaxation and structural dynamics of indigo carmine in dimethyl sulfoxide were examined using femtosecond pump–probe infrared and two-dimensional infrared (2D IR) spectroscopies. Using the intramolecularly hydrogen-Bonded C═O and delocalized C═C stretching modes as infrared probes, local structural and dynamical variations of this blue dye molecule were observed. Energy relaxation of the vibrationally excited C═O stretching mode was found to occur through Covalent Bond to the delocalized aromatic vibrational modes on the time scale of a few picoseconds or less. Vibrational quantum beating was observed in magic-angle pump–probe, anisotropy, and 2D IR cross-peak dynamics, showing an oscillation period of ca. 1010 fs, which corresponds to the energy difference between the C═O and C═C transition frequency (33 cm–1). This confirms a resonant vibrational energy transfer happened between the two vibrators. However, a more efficient energy-accepting mode of the excited C═O stretching was be...
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efficient vibrational energy transfer through Covalent Bond in indigo carmine revealed by nonlinear ir spectroscopy
The Journal of Physical Chemistry, 2017Co-Authors: Xuemei He, Pengyun Yu, Juan Zhao, Jianping WangAbstract:Ultrafast vibrational relaxation and structural dynamics of indigo carmine in dimethyl sulfoxide were examined using femtosecond pump–probe infrared and two-dimensional infrared (2D IR) spectroscopies. Using the intramolecularly hydrogen-Bonded CO and delocalized CC stretching modes as infrared probes, local structural and dynamical variations of this blue dye molecule were observed. Energy relaxation of the vibrationally excited CO stretching mode was found to occur through Covalent Bond to the delocalized aromatic vibrational modes on the time scale of a few picoseconds or less. Vibrational quantum beating was observed in magic-angle pump–probe, anisotropy, and 2D IR cross-peak dynamics, showing an oscillation period of ca. 1010 fs, which corresponds to the energy difference between the CO and CC transition frequency (33 cm–¹). This confirms a resonant vibrational energy transfer happened between the two vibrators. However, a more efficient energy-accepting mode of the excited CO stretching was believed to be a nearby combination and/or overtone mode that is more tightly connected to the CO species. On the structural aspect, dynamical-time-dependent 2D IR spectra reveal an insignificant inhomogeneous contribution to time-correlation relaxation for both the CO and CC stretching modes, which is in agreement with the generally believed structural rigidity of such conjugated molecules.
Geoffroy Auvert - One of the best experts on this subject based on the ideXlab platform.
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coherence of the even odd rule with an effective valence isoelectronicity rule for chemical structural formulas application to known and unknown single Covalent Bonded compounds
Open Journal of Physical Chemistry, 2014Co-Authors: Geoffroy AuvertAbstract:Ions or molecules are said to be isoelectronic if they are composed of different elements but have the same number of electrons, the same number of Covalent Bonds and the same structure. This criterion is unfortunately not sufficient to ensure that a chemical structure is a valid chemical compound. In a previous article, a procedure has been described to draw 2D valid structural formulas: the even-odd rule. This rule has been applied first to single-Bonded molecules then to single-charged single-Bonded ions. It covers hypovalent, hypervalent or classic Lewis’ octet compounds. The funding principle of the even-odd rule is that each atom of the compound possesses an outer-shell filled only with pairs of electrons. The application of this rule guarantees validity of any single-Covalent-Bond chemical structure. In the present paper, this even-odd rule and its electron-pair criterion are checked for coherence with an effective-valence isoelectronic rule using numerous known compounds having single-Covalent-Bond connections. The test addresses Lewis’ octet ions or molecules as well as hypovalent and hypervalent compounds. The article concludes that the even-odd rule and the effective-valence isoelectronicity rule are coherent for known single-Covalent-Bond chemical compounds.
Wenrong Yang - One of the best experts on this subject based on the ideXlab platform.
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real time electrochemical monitoring of Covalent Bond formation in solution via nanoparticle electrode collisions
Chemical Communications, 2015Co-Authors: Na Kong, Jingquan Liu, Hongbin Wang, Colin J Barrow, Shusheng Zhang, Wenrong YangAbstract:We describe an alternative electrochemical technique to monitor Covalent Bond formation in real-time using nanoparticle-electrode collisions. The method is based on recognising the redox current when MP-11 functionalised chemical reduced graphene oxide (rGO) nanosheets collide with Lomant's reagent modified gold microelectrode. This facile and highly sensitive monitoring method can be useful for investigating the fundamental of single-molecule reactions.
Rint P. Sijbesma - One of the best experts on this subject based on the ideXlab platform.
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mechanoluminescent imaging of osmotic stress induced damage in a glassy polymer network
Macromolecules, 2017Co-Authors: J Jessica M Clough, Jasper Van Der Gucht, Rint P. SijbesmaAbstract:A chemiluminescent mechanophore, bis(adamantyl-1,2-dioxetane), is used to investigate the Covalent Bond scission resulting from the sorption of chloroform by glassy poly(methyl methacrylate) (PMMA) networks. Bis(adamantyl)-1,2-dioxetane units incorporated as cross-linkers underwent mechanoluminescent scission, demonstrating that solvent ingress caused Covalent Bond scission. At higher cross-linking densities, the light emission took the form of hundreds of discrete bursts, widely varying in intensity, with each burst composed of 107–109 photons. Camera imaging indicated a relatively slow propagation of bursts through the material and permitted analysis of the spatial correlation between the discrete Bond-breaking events. The implications of these observations for the mechanism of sorption and fracture are discussed.
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Covalent Bond Scission in the Mullins Effect of a Filled Elastomer: Real-Time Visualization with Mechanoluminescence
Advanced Functional Materials, 2016Co-Authors: Jess M. Clough, Costantino Creton, Stephen L. Craig, Rint P. SijbesmaAbstract:Strain-induced light emission from mechanoluminescent cross-linkers in silica-filled poly(dimethylsiloxane) demonstrates that Covalent Bond scission contributes significantly to irreversible stress-softening upon the initial extension, known as the Mullins effect. The cross-linkers contain dioxetanes that emit light upon force-induced Bond scission. The filled elastomer emits light in cyclic uniaxial tension, but only on exceeding the previous maximum strain. The amount of light increases with hysteresis energy in a power law of exponent 2.0, demonstrating that Covalent Bond scission becomes increasingly important in the strain regime studied. Below 100%–120% strain, corresponding to energy absorption of (0.082 ± 0.012) J cm−3, mechanoluminescence is not detectable. Calibration of the light intensity indicates that by 190% strain, less than 0.1% of the dioxetane moieties break. Small but significant amounts of light are emitted upon unloading, suggesting a complex stress transfer to the dioxetanes mediated by the fillers. Pre-strained material emits light on straining perpendicularly, but not parallel to the original tensile direction, demonstrating that Covalent Bond scission is highly anisotropic. These findings show that the scission of even a small number of Covalent Bonds plays a discernible role in the Mullins effect in filled silicone elastomers. Such mechanisms may be active in other types of filled elastomers.
Xuemei He - One of the best experts on this subject based on the ideXlab platform.
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efficient vibrational energy transfer through Covalent Bond in indigo carmine revealed by nonlinear ir spectroscopy
Journal of Physical Chemistry B, 2017Co-Authors: Xuemei He, Pengyun Yu, Juan Zhao, Jianping WangAbstract:Ultrafast vibrational relaxation and structural dynamics of indigo carmine in dimethyl sulfoxide were examined using femtosecond pump–probe infrared and two-dimensional infrared (2D IR) spectroscopies. Using the intramolecularly hydrogen-Bonded C═O and delocalized C═C stretching modes as infrared probes, local structural and dynamical variations of this blue dye molecule were observed. Energy relaxation of the vibrationally excited C═O stretching mode was found to occur through Covalent Bond to the delocalized aromatic vibrational modes on the time scale of a few picoseconds or less. Vibrational quantum beating was observed in magic-angle pump–probe, anisotropy, and 2D IR cross-peak dynamics, showing an oscillation period of ca. 1010 fs, which corresponds to the energy difference between the C═O and C═C transition frequency (33 cm–1). This confirms a resonant vibrational energy transfer happened between the two vibrators. However, a more efficient energy-accepting mode of the excited C═O stretching was be...
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efficient vibrational energy transfer through Covalent Bond in indigo carmine revealed by nonlinear ir spectroscopy
The Journal of Physical Chemistry, 2017Co-Authors: Xuemei He, Pengyun Yu, Juan Zhao, Jianping WangAbstract:Ultrafast vibrational relaxation and structural dynamics of indigo carmine in dimethyl sulfoxide were examined using femtosecond pump–probe infrared and two-dimensional infrared (2D IR) spectroscopies. Using the intramolecularly hydrogen-Bonded CO and delocalized CC stretching modes as infrared probes, local structural and dynamical variations of this blue dye molecule were observed. Energy relaxation of the vibrationally excited CO stretching mode was found to occur through Covalent Bond to the delocalized aromatic vibrational modes on the time scale of a few picoseconds or less. Vibrational quantum beating was observed in magic-angle pump–probe, anisotropy, and 2D IR cross-peak dynamics, showing an oscillation period of ca. 1010 fs, which corresponds to the energy difference between the CO and CC transition frequency (33 cm–¹). This confirms a resonant vibrational energy transfer happened between the two vibrators. However, a more efficient energy-accepting mode of the excited CO stretching was believed to be a nearby combination and/or overtone mode that is more tightly connected to the CO species. On the structural aspect, dynamical-time-dependent 2D IR spectra reveal an insignificant inhomogeneous contribution to time-correlation relaxation for both the CO and CC stretching modes, which is in agreement with the generally believed structural rigidity of such conjugated molecules.
