With recent developments of sophisticated experimental techniques and advanced theoretical methods/computations, the field of chemical dynamics has reached the point that theoryexperiment comparisons can be made at a ...With recent developments of sophisticated experimental techniques and advanced theoretical methods/computations, the field of chemical dynamics has reached the point that theoryexperiment comparisons can be made at a quantitative level in very fine details for a prototypical A+BC system. As the system becomes larger, more degrees of freedom are involved and the complexity increases exponentially. At the same time, the multifaceted nature of polyatomic systems also opens up the possibilities for observing many new chemistry and novel phenomena|a land of opportunities. For the past 15 years or so my laboratory has delved into the reaction dynamics of methane+X (X: F, Cl, O(3P), and OH). This effort shifts the paradigm in the field of reaction dynamics by making the title reaction a benchmark polyatomic system. In this account, I shall disclose my thinking behind some of the key concepts and methods we introduced and how the unexpectedly discovered phenomena led to other uncharted territories. Those ndings not only enrich our understanding of the specific reactions we studied at the most fundamental level and inspire the theoretical developments, but also shape our thinking and lay the foundation for future explorations of different aspects of the multifaceted nature of polyatomic reactivity.展开更多
Various bond modes of the M-C（C5 ring） exist in metallocene compounds of group 14 heavier elements,mostly due to an intricate interaction between the lone electron pairs at the M center and the 6 p-electrons of the ...Various bond modes of the M-C（C5 ring） exist in metallocene compounds of group 14 heavier elements,mostly due to an intricate interaction between the lone electron pairs at the M center and the 6 p-electrons of the C5 ring.The tin（Ⅱ） metallocene complexes LSn R（L = HC[CMe（N-2,6-iPr2C6H3）]2,R = cyclopentadienyl,C5H5（1）; indenyl,C9H7（2）; fluorenyl,C（13）H9（3）） stabilized by the β-diketiminato ligand were prepared and utilized in the study on their solid and solution state structures.X-ray single-crystal diffraction data revealed an η~1-mode of the Sn-C（C5 ring） bond in each 1~3.However,the room temperature ~1H NMR spectral studies disclosed such a fluxional bonding mode in solution.The 119 Sn NMR studies suggested a quadruple coordination nature of the Sn center in 1 while the triple coordination manner was for the Sn atom in both 2 and 3.Then the variable-temperature（25~–75 ℃） ~1H NMR spectral studies for each 1~3 were performed,which detected the relaxation state structures of 1~3 at lower temperature.All of these results indicate a stereochemical activity of the lone electron pairs at the tin（Ⅱ） atom that definitely has an electronic interaction with the 6 p-electrons of the C5 ring.The observed Sn-C（C5 ring） bond modes appear influenced by either the metallocene size or the compound state existed.展开更多
We designed and fabricated a smart microcavity sensor with a vertically coupled structure on the end face of a multi-core fiber using two-photon lithography technology. The influence of gap in vertical coupling struct...We designed and fabricated a smart microcavity sensor with a vertically coupled structure on the end face of a multi-core fiber using two-photon lithography technology. The influence of gap in vertical coupling structure on the resonance characteristics of bonding and anti-bonding modes in the transmission spectrum was studied through simulation and experiments. The results indicate that the bonding and anti-bonding modes generated by the vertical coupling of the two microcavities, as well as the changes in the radius and refractive index of the micro-toroid, and the distance between the microcavities caused by the absorption of vapor during the gas sensing process, exhibit different wavelength shifts for the two resonant modes. Smart microcavity sensors exhibit sensitivity and sensing characteristics. .展开更多
The structure design,performance analysis,and process optimization of CNT/MOF-derived hierarchical composite play an important role in the development of high-performance microwave absorbing materi-als.Herein,the prep...The structure design,performance analysis,and process optimization of CNT/MOF-derived hierarchical composite play an important role in the development of high-performance microwave absorbing materi-als.Herein,the preparation,morphology evolution,and electromag-netic wave absorption mechanism of CNT/MOF-derived hierarchical composite were systematically investigated.The regulation mechan-ism was revealed by studying the changes in the morphological characteristics,electromagnetic properties,and microwave absorbing performance of CNT/MOF-derived hierarchical composite under differ-ent process parameters.The results show that the morphological characteristics and interface bonding between CNT and MOF have a great impact on the absorptive capacity.The composite with com-position of 0.28Co/0.26Fe has a maximum absorption of−46 dB at 8.6 GHz and a thickness of 4 mm.In addition,the absorption band with reflection loss values of less than−20 dB can be operated with this thickness between 7.15 and 10.18 GHz,showing excellent absorbing ability and electromagnetic wave bandwidth.The regulation mechan-ism of CNT/MOF-derived hierarchical composite mainly depends on the effect of Lorentz force,the ion disorder of CoO-Fe_(2)O_(3) heterojunc-tion,and the spin polarization mechanism of free electrons.This study further improves the corresponding theoretical basis and new design principles,which provides technical support for the development of high-performance absorbing materials.展开更多
基金Academia Sinicathe Minster of Science and Technology of Taiwan (formerly, the National Science of Council) for their generous financial supports
文摘With recent developments of sophisticated experimental techniques and advanced theoretical methods/computations, the field of chemical dynamics has reached the point that theoryexperiment comparisons can be made at a quantitative level in very fine details for a prototypical A+BC system. As the system becomes larger, more degrees of freedom are involved and the complexity increases exponentially. At the same time, the multifaceted nature of polyatomic systems also opens up the possibilities for observing many new chemistry and novel phenomena|a land of opportunities. For the past 15 years or so my laboratory has delved into the reaction dynamics of methane+X (X: F, Cl, O(3P), and OH). This effort shifts the paradigm in the field of reaction dynamics by making the title reaction a benchmark polyatomic system. In this account, I shall disclose my thinking behind some of the key concepts and methods we introduced and how the unexpectedly discovered phenomena led to other uncharted territories. Those ndings not only enrich our understanding of the specific reactions we studied at the most fundamental level and inspire the theoretical developments, but also shape our thinking and lay the foundation for future explorations of different aspects of the multifaceted nature of polyatomic reactivity.
基金supported by the National Natural Science Foundation of China(21473142 and 21673191)the National Innovative Research Team of China(IRT_14R31 and J1310024)
文摘Various bond modes of the M-C（C5 ring） exist in metallocene compounds of group 14 heavier elements,mostly due to an intricate interaction between the lone electron pairs at the M center and the 6 p-electrons of the C5 ring.The tin（Ⅱ） metallocene complexes LSn R（L = HC[CMe（N-2,6-iPr2C6H3）]2,R = cyclopentadienyl,C5H5（1）; indenyl,C9H7（2）; fluorenyl,C（13）H9（3）） stabilized by the β-diketiminato ligand were prepared and utilized in the study on their solid and solution state structures.X-ray single-crystal diffraction data revealed an η~1-mode of the Sn-C（C5 ring） bond in each 1~3.However,the room temperature ~1H NMR spectral studies disclosed such a fluxional bonding mode in solution.The 119 Sn NMR studies suggested a quadruple coordination nature of the Sn center in 1 while the triple coordination manner was for the Sn atom in both 2 and 3.Then the variable-temperature（25~–75 ℃） ~1H NMR spectral studies for each 1~3 were performed,which detected the relaxation state structures of 1~3 at lower temperature.All of these results indicate a stereochemical activity of the lone electron pairs at the tin（Ⅱ） atom that definitely has an electronic interaction with the 6 p-electrons of the C5 ring.The observed Sn-C（C5 ring） bond modes appear influenced by either the metallocene size or the compound state existed.
文摘We designed and fabricated a smart microcavity sensor with a vertically coupled structure on the end face of a multi-core fiber using two-photon lithography technology. The influence of gap in vertical coupling structure on the resonance characteristics of bonding and anti-bonding modes in the transmission spectrum was studied through simulation and experiments. The results indicate that the bonding and anti-bonding modes generated by the vertical coupling of the two microcavities, as well as the changes in the radius and refractive index of the micro-toroid, and the distance between the microcavities caused by the absorption of vapor during the gas sensing process, exhibit different wavelength shifts for the two resonant modes. Smart microcavity sensors exhibit sensitivity and sensing characteristics. .
基金This work was supported by the Natural Science Basic Research Plan in Shaanxi Province of China[Grant No.2016JQ5046]the National Natural Science Foundation of China[Grant No.51672209]the National Key R&D Program of China[Grant Nos.2017YFB0310300 and 2017YFB0903803].
文摘The structure design,performance analysis,and process optimization of CNT/MOF-derived hierarchical composite play an important role in the development of high-performance microwave absorbing materi-als.Herein,the preparation,morphology evolution,and electromag-netic wave absorption mechanism of CNT/MOF-derived hierarchical composite were systematically investigated.The regulation mechan-ism was revealed by studying the changes in the morphological characteristics,electromagnetic properties,and microwave absorbing performance of CNT/MOF-derived hierarchical composite under differ-ent process parameters.The results show that the morphological characteristics and interface bonding between CNT and MOF have a great impact on the absorptive capacity.The composite with com-position of 0.28Co/0.26Fe has a maximum absorption of−46 dB at 8.6 GHz and a thickness of 4 mm.In addition,the absorption band with reflection loss values of less than−20 dB can be operated with this thickness between 7.15 and 10.18 GHz,showing excellent absorbing ability and electromagnetic wave bandwidth.The regulation mechan-ism of CNT/MOF-derived hierarchical composite mainly depends on the effect of Lorentz force,the ion disorder of CoO-Fe_(2)O_(3) heterojunc-tion,and the spin polarization mechanism of free electrons.This study further improves the corresponding theoretical basis and new design principles,which provides technical support for the development of high-performance absorbing materials.
