The equilibrium structures and the electronic, spectroscopic and thermodynamic properties of small Pun （n = 2- 5） molecules are systematically investigated using the methods of general gradient approximation （GGA）...The equilibrium structures and the electronic, spectroscopic and thermodynamic properties of small Pun （n = 2- 5） molecules are systematically investigated using the methods of general gradient approximation （GGA） of density functional theory （DFT）. The results show that the bond length of the lowest-energy structure of Pu2 is 2.578 A. The ground state structure of Pu3 is a triangle with D3h symmetry, whereas for Pu4, the ground state structure is a square （D4h） and the spin polarization of 16 for molecule Pu5 with square geometry （D_4h） is the most stable structure. For the ground state structures, the vibrational spectra as well as thermodynamic parameters are worked out. In addition, the values for the highest occupied molecular orbital （HOMO） and the lowest unoccupied molecular orbital （LUMO） along with the energy gap of all the Pu_2-5 structures are presented. The relevant structural and chemical stabilities are predicted.展开更多
Ultrafast dynamics and third-order nonlinearity of thin films of tert-butyl peripherally-substituted indium phthalocyanine axlally grafted polystyrene （tBu4PcIn-PS） are investigated by femtosecond optical-Kerr-effe...Ultrafast dynamics and third-order nonlinearity of thin films of tert-butyl peripherally-substituted indium phthalocyanine axlally grafted polystyrene （tBu4PcIn-PS） are investigated by femtosecond optical-Kerr-effect （OKE） and z-scan experiments. The fastest component （〈 200 fs） in the OKE traces of the film is related to the electron cloud distortion, where the phthalocyanine-polymer interaction may enhance this contribution. The z-scan measurement also indicates that this interaction might enhance the third-order optical nonlinearity. The measurements shows that the magnitudes of X（3） of these films are in order of 10^-11 esu.展开更多
We demonstrate theoretically that two-dimensional photonic bandgap materials are indeed perfect polarizers provided that they have a proper photonic band structure along the incident direction of light.This kind of po...We demonstrate theoretically that two-dimensional photonic bandgap materials are indeed perfect polarizers provided that they have a proper photonic band structure along the incident direction of light.This kind of polarizer is fundamentally different from the conventional ones.It can function in a wide frequency range with high performance and its size can be made very compact,which renders it useful as a micropolarizer in micro-optics.展开更多
Based on plasma dispersion of Si_(1-x)Ge_(x),the single mode waveguide modulators consisting of Si_(1-x)Ge_(x)/Si and Si/Si_(1-x)Ge_(x)/Si which were grown by molecular beam epitaxy have been fabricated.For Si_(1-x)Ge...Based on plasma dispersion of Si_(1-x)Ge_(x),the single mode waveguide modulators consisting of Si_(1-x)Ge_(x)/Si and Si/Si_(1-x)Ge_(x)/Si which were grown by molecular beam epitaxy have been fabricated.For Si_(1-x)Ge_(x)/Si structure,the switch current and insertion loss at wavelength 1.3 fiin are 36 mA and 2.8 dB,respectively.The switching response time is 40 ns.展开更多
文摘The equilibrium structures and the electronic, spectroscopic and thermodynamic properties of small Pun （n = 2- 5） molecules are systematically investigated using the methods of general gradient approximation （GGA） of density functional theory （DFT）. The results show that the bond length of the lowest-energy structure of Pu2 is 2.578 A. The ground state structure of Pu3 is a triangle with D3h symmetry, whereas for Pu4, the ground state structure is a square （D4h） and the spin polarization of 16 for molecule Pu5 with square geometry （D_4h） is the most stable structure. For the ground state structures, the vibrational spectra as well as thermodynamic parameters are worked out. In addition, the values for the highest occupied molecular orbital （HOMO） and the lowest unoccupied molecular orbital （LUMO） along with the energy gap of all the Pu_2-5 structures are presented. The relevant structural and chemical stabilities are predicted.
基金Supported by the National Natural Science Foundation of China under Grant Nos 10274013, 10374020, and 20546002, the East China University of Science and Technology/Ireland Science and Technology Collaboration Research Foundation （No CI-2004-06）, SRF for R0CS, and STCSM （No 05XD14004）.
文摘Ultrafast dynamics and third-order nonlinearity of thin films of tert-butyl peripherally-substituted indium phthalocyanine axlally grafted polystyrene （tBu4PcIn-PS） are investigated by femtosecond optical-Kerr-effect （OKE） and z-scan experiments. The fastest component （〈 200 fs） in the OKE traces of the film is related to the electron cloud distortion, where the phthalocyanine-polymer interaction may enhance this contribution. The z-scan measurement also indicates that this interaction might enhance the third-order optical nonlinearity. The measurements shows that the magnitudes of X（3） of these films are in order of 10^-11 esu.
基金Supported by the National Key Basic Research Special Fund of China, the National Natural Science Foundation of China, and the Shanghai Science and Technology Commission.
基金Supported in part by the National Natural Science Foundation of China under Grant No.69625609,Pandeng plan(Y-41)Shanghai Science and Technology Commission.
文摘We demonstrate theoretically that two-dimensional photonic bandgap materials are indeed perfect polarizers provided that they have a proper photonic band structure along the incident direction of light.This kind of polarizer is fundamentally different from the conventional ones.It can function in a wide frequency range with high performance and its size can be made very compact,which renders it useful as a micropolarizer in micro-optics.
基金Supported by the National Natural Science Foundation of China.
文摘Based on plasma dispersion of Si_(1-x)Ge_(x),the single mode waveguide modulators consisting of Si_(1-x)Ge_(x)/Si and Si/Si_(1-x)Ge_(x)/Si which were grown by molecular beam epitaxy have been fabricated.For Si_(1-x)Ge_(x)/Si structure,the switch current and insertion loss at wavelength 1.3 fiin are 36 mA and 2.8 dB,respectively.The switching response time is 40 ns.
