The effect of interchain coupling on the formation and the stability of a biexciton is studied in poly （p-phenylene vinylene） chains in the framework of the tight-binding approach. We obtain an intrachain exciton an...The effect of interchain coupling on the formation and the stability of a biexciton is studied in poly （p-phenylene vinylene） chains in the framework of the tight-binding approach. We obtain an intrachain exciton and biexciton as well as an interchain exciton and biexciton through a double-photon excitation.It is found that a biexciton is energetically favourable to two single excitons even when there exists an interchain coupling.There is a turnover value t⊥c of the interchain coupling for the formation of a biexciton,beyond which two excitons are combined into one biexciton.The binding energy of a biexciton is calculated to decrease with the increase of interchain coupling,which indicates that a biexciton is relatively stable in polymers with a weak interchain coupling.The conclusion is consistent with the experimental observations.In addition,a suggestion about how to improve the yielding efficiency or the formation of biexcitons in actual applications is given.展开更多
Photocatalytic aerobic oxidation reactions are largely governed by the efficiency of charge separation and subsequent reactive oxygen species(ROS) generation. Herein, we report a polarization engineering strategy to p...Photocatalytic aerobic oxidation reactions are largely governed by the efficiency of charge separation and subsequent reactive oxygen species(ROS) generation. Herein, we report a polarization engineering strategy to promote the charge separation and ROS generation efficiency by substituting the benzene unit with furan/thiophene in porous organic polymers(POPs). Benefiting from the extent of local polarization, the thiophene-containing POP(JNU-218) exhibits the best photocatalytic performance in aerobic oxidation reactions, with a yield much higher than those for the furan-containing POP(JNU-217) and the benzenecontaining POP(JNU-216). Experimental studies and theoretical calculations reveal that the increase of local polarization can indeed reduce the exciton binding energy, and therefore facilitate the separation of electron-hole pairs. This work demonstrates a viable strategy to tune charge separation and ROS generation efficiency by modulating the dipole moments of the building blocks in porous polymeric organic semiconductors.展开更多
Molecular dynamics （MD） method was used to simulate 1,3,5-triamino-2,4,6-trinitrobenzene （TATB） coated with fluorine containing polymers. The mechanical properties and binding energies of PBXs were obtained. It wa...Molecular dynamics （MD） method was used to simulate 1,3,5-triamino-2,4,6-trinitrobenzene （TATB） coated with fluorine containing polymers. The mechanical properties and binding energies of PBXs were obtained. It was found that when the number of chain monomers of fluorine containing polymers was the same, the elasticity of TATB/F2314 was increased more greatly than others and the binding energy of TATB/F2311 was the largest among four PBXs. Detonation heat and velocity of such four PBXs were calculated according to theoretical and empirical formulas. The results show that the order of detonation heat is TATB〉TATB/PVDF〉TATB/F2311〉TATB/ F2314 〉 TATB/PCTFE while the order of detonation velocity is TATB/PVDF 〈 TATB/F2311 〈 TATB/F2314 〈 TATB/PCTFE 〈TATB.展开更多
The molecular simulations of the well-known high explosive β-HMX (cyclotetramethylene tetranitramine) anditsfluorine containing polymer-bonded explosives(PBXs) were carried out with the combination method of quantum ...The molecular simulations of the well-known high explosive β-HMX (cyclotetramethylene tetranitramine) anditsfluorine containing polymer-bonded explosives(PBXs) were carried out with the combination method of quantum mechanics, molecular mechanics and molecular dynamics. The atomic cluster model, containing the β-HMX molecule and the polymer molecule whose chain dimension was about the same as β-HMX’s, was fully optimized by AM1 and PM3 semi-empirical molecular orbital and molecular mechanical methods using COMPASS and PCFF force field. Then the calculated binding energy is found to be linearly correlated to each other. Molecular dynamics simulations using COM- PASS force field were performed for β-HMX crystal and the PBXs involving β-HMX and a series of fluorine containing polymers. Their elastic coefficients, moduli and Poisson’s ratios were calculated. It is found that the mechanical prop- erties of β-HMX can be effectively improved by blending with fluorine containing polymers in small amounts.展开更多
在对In As单量子点施加流体静压的实验中,使用了带有压电陶瓷的连续加压装置,在低温连续施加流体静压的情况下,可以调节量子点单激子能量兰移约320 me V。在对不同流体静压下单激子发光的二阶关联函数测量之后,证明流体静压并不影响单...在对In As单量子点施加流体静压的实验中,使用了带有压电陶瓷的连续加压装置,在低温连续施加流体静压的情况下,可以调节量子点单激子能量兰移约320 me V。在对不同流体静压下单激子发光的二阶关联函数测量之后,证明流体静压并不影响单激子发光的单光子特性。同时通过流体静压,可以实现量子点双激子态由反束缚态到束缚态的转变,并且给出了这一过程的偏振分辨光谱图。最后观察到单量子点精细结构劈裂随流体静压的增加而增加,而且精细结构劈裂的增加量可以达到约150μe V。展开更多
基金Project supported by the National Natural Science Foundation of China (Grant Nos 10804062 and 10874100)the Specialized Research Fund for the Doctoral Program of Higher Education of China (Grant Nos 200804221005 and 20070422058)China Postdoctoral Science Foundation funded project (Grant No 20080431171)
文摘The effect of interchain coupling on the formation and the stability of a biexciton is studied in poly （p-phenylene vinylene） chains in the framework of the tight-binding approach. We obtain an intrachain exciton and biexciton as well as an interchain exciton and biexciton through a double-photon excitation.It is found that a biexciton is energetically favourable to two single excitons even when there exists an interchain coupling.There is a turnover value t⊥c of the interchain coupling for the formation of a biexciton,beyond which two excitons are combined into one biexciton.The binding energy of a biexciton is calculated to decrease with the increase of interchain coupling,which indicates that a biexciton is relatively stable in polymers with a weak interchain coupling.The conclusion is consistent with the experimental observations.In addition,a suggestion about how to improve the yielding efficiency or the formation of biexcitons in actual applications is given.
基金supported by the National Natural Science Foundation of China(21731002,21975104,22101099,22150004,22271120)Guangdong Major Project of Basic and Applied Research(2019B030302009)+1 种基金the Outstanding Innovative Talents Cultivation Funded Programs for Doctoral Students of Jinan University(2022CXB007)the Fundamental Research Funds for the Central Universities and Jinan University(21621035)。
文摘Photocatalytic aerobic oxidation reactions are largely governed by the efficiency of charge separation and subsequent reactive oxygen species(ROS) generation. Herein, we report a polarization engineering strategy to promote the charge separation and ROS generation efficiency by substituting the benzene unit with furan/thiophene in porous organic polymers(POPs). Benefiting from the extent of local polarization, the thiophene-containing POP(JNU-218) exhibits the best photocatalytic performance in aerobic oxidation reactions, with a yield much higher than those for the furan-containing POP(JNU-217) and the benzenecontaining POP(JNU-216). Experimental studies and theoretical calculations reveal that the increase of local polarization can indeed reduce the exciton binding energy, and therefore facilitate the separation of electron-hole pairs. This work demonstrates a viable strategy to tune charge separation and ROS generation efficiency by modulating the dipole moments of the building blocks in porous polymeric organic semiconductors.
基金Project supported by the Significant Fundation of China Academy of Engineering Physics （No. 2004Z0503） and the National Natural Science Foundation of China （No. 10176012）.
文摘Molecular dynamics （MD） method was used to simulate 1,3,5-triamino-2,4,6-trinitrobenzene （TATB） coated with fluorine containing polymers. The mechanical properties and binding energies of PBXs were obtained. It was found that when the number of chain monomers of fluorine containing polymers was the same, the elasticity of TATB/F2314 was increased more greatly than others and the binding energy of TATB/F2311 was the largest among four PBXs. Detonation heat and velocity of such four PBXs were calculated according to theoretical and empirical formulas. The results show that the order of detonation heat is TATB〉TATB/PVDF〉TATB/F2311〉TATB/ F2314 〉 TATB/PCTFE while the order of detonation velocity is TATB/PVDF 〈 TATB/F2311 〈 TATB/F2314 〈 TATB/PCTFE 〈TATB.
基金the National Natural Science Foundation of China(Grant Nos.10176012 and 20173028).
文摘The molecular simulations of the well-known high explosive β-HMX (cyclotetramethylene tetranitramine) anditsfluorine containing polymer-bonded explosives(PBXs) were carried out with the combination method of quantum mechanics, molecular mechanics and molecular dynamics. The atomic cluster model, containing the β-HMX molecule and the polymer molecule whose chain dimension was about the same as β-HMX’s, was fully optimized by AM1 and PM3 semi-empirical molecular orbital and molecular mechanical methods using COMPASS and PCFF force field. Then the calculated binding energy is found to be linearly correlated to each other. Molecular dynamics simulations using COM- PASS force field were performed for β-HMX crystal and the PBXs involving β-HMX and a series of fluorine containing polymers. Their elastic coefficients, moduli and Poisson’s ratios were calculated. It is found that the mechanical prop- erties of β-HMX can be effectively improved by blending with fluorine containing polymers in small amounts.
文摘在对In As单量子点施加流体静压的实验中,使用了带有压电陶瓷的连续加压装置,在低温连续施加流体静压的情况下,可以调节量子点单激子能量兰移约320 me V。在对不同流体静压下单激子发光的二阶关联函数测量之后,证明流体静压并不影响单激子发光的单光子特性。同时通过流体静压,可以实现量子点双激子态由反束缚态到束缚态的转变,并且给出了这一过程的偏振分辨光谱图。最后观察到单量子点精细结构劈裂随流体静压的增加而增加,而且精细结构劈裂的增加量可以达到约150μe V。
