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  • 1
    In: Acta Physica Sinica, Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences, Vol. 50, No. 7 ( 2001), p. 1264-
    Abstract: The preparation of carbon buckonions is reported.Large quantities and high percentage of carbon buckonions can be synthesised by radio frequency plasma-enhanced chemical vapor deposition on the Co catalysts and Co-SiO2 catalysts.The product contains no carbon tubes,only carbon onions,which are solid,smooth and clean and can be separated easily from the catalystic particles.The growth of carbon buckonions is based on the formation of many cages in successive stages from the core to the surface.High-resolution transmission electron microscopy indicates that the outer layers of the carbon buckonions produced on Co-SiO2 comprise unclosed small waving graphitic flakes.The formation process of these graphitic flakes is discussed.
    Type of Medium: Online Resource
    ISSN: 1000-3290 , 1000-3290
    Language: Unknown
    Publisher: Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences
    Publication Date: 2001
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  • 2
    Online Resource
    Online Resource
    Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences ; 2014
    In:  Acta Physica Sinica Vol. 63, No. 2 ( 2014), p. 023102-
    In: Acta Physica Sinica, Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences, Vol. 63, No. 2 ( 2014), p. 023102-
    Abstract: In order to study the influence of external electric field on ZrO2, molecular structure of ZrO2 ground state is optimized by density functional theory (B3P86) method with 6-311++G* basis sets for O atom and aug-cc-pVTZ-PP for Zr atom. The effects of electric field ranging from 0 to 0.025 a.u. are investigated on bond length, total energy, charge distribution, dipole moment, HOMO (the highest occupied molecular orbital) energy level, LUMO (the lowest unoccupied molecular orbital) energy level and energy gap. The excitation energies, transition wavelengths and oscillator strengths under the same intense external electric fields are calculated by the time dependent density functional theory (TD-B3P86) method. The result shows that the bond length of Zr-2O and total energy increase with external field increasing, but the bond lengths of Zr-3O, LUMOs and energy gaps decrease, and HOMOs almost keep the same. The excitation energies decrease and the transition wavelengths of the six excited states are red shifted toward longer wavelength as the applied electric field increases. Therefore the spectral region of zirconiumdioxide molecule can be expanded in visible-infrared region by the use of external electric fields.
    Type of Medium: Online Resource
    ISSN: 1000-3290 , 1000-3290
    Language: Unknown
    Publisher: Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences
    Publication Date: 2014
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  • 3
    Online Resource
    Online Resource
    Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences ; 2013
    In:  Acta Physica Sinica Vol. 62, No. 22 ( 2013), p. 223102-
    In: Acta Physica Sinica, Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences, Vol. 62, No. 22 ( 2013), p. 223102-
    Abstract: Polychlorinated biphenyls (PCBs) are persistent organic pollutant, and 2, 2, 5, 5-tetrachlorobiphenyl is generally used as a model molecule of PCBs in some studies. PCB52 molecule is degraded under external electric fields. The molecular structure of PCB ground state is optimized by density functional theory (B3LYP) method with 6-311+g(d) basis sets. The effects of electric fields ranging from-0.04 a.u. to 0.04 a.u. are investigated on structural parameters, total energy, dipole moment and charges distribution. The transition wavelengths, oscillator strengths and excitation energies of the first six excited states under external electric fields are calculated by the time dependent density functional theory method. The result shows that the bond lengths of 1C21Cl and 14C20Cl increase with external electric field increasing. The dihedral angle of two benzene rings of PCB52 molecule increases under the electric fields, and the PCB52 molecule reduces toxicity. PCB52 molecule energy gaps decrease, leading to the fact that the molecule is susceptible to excitation to an excited state and reductive dechlorination reaction. As the increase of the applied electric field, the excitation energies rapidly decrease, absorption wavelengths are red-shifted toward longer wavelength and oscillator strength is no longer zero, which indicates that the PCB52 molecule is easily excited and dissociated.
    Type of Medium: Online Resource
    ISSN: 1000-3290 , 1000-3290
    Language: Unknown
    Publisher: Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences
    Publication Date: 2013
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  • 4
    Online Resource
    Online Resource
    Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences ; 2021
    In:  Acta Physica Sinica Vol. 70, No. 5 ( 2021), p. 053102-
    In: Acta Physica Sinica, Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences, Vol. 70, No. 5 ( 2021), p. 053102-
    Abstract: Tert-butylhydroquinone (TBHQ) is an important food antioxidant. Based on density functional theory, the B3LYP functional is used to optimize the geometric configuration and calculate the frequency of TBHQ molecule in gas phase at a level of 6-311g (d, p) basis set. On this basis, based on the time-dependent density functional theory, SMD implicit solvent model is selected, and the first 50 excited states of molecule in ethanol solvent are calculated by using B3LYP functional and def2-TZVP basis set. Multiwfn software is used to analyze the vibration of IR spectrum, the influence of interaction among molecules on IR spectrum and the molecular orbital and electron-hole of UV spectrum. Experimentally, Fourier transform infrared spectrometer (FTIR) is used to measure the IR spectrum of TBHQ sample by KBr tablet method. The UV spectrum of the sample determined in the ethanol solvent by ultraviolet visible spectrophotometer. By comparative analysis, it can be seen that the theoretical spectra are in good agreement with the experimental spectra. The characteristic absorption peaks of each group in the IR spectra are obvious, and the theoretical peaks are in good agreement with the positions of the measured peaks. The hydrogen bonding of dimers and polymers in the TBHQ sample can weaken the O—H bond strength of a single molecule, thus weakening the vibration frequency of the O—H bond and resulting in a wide peak at 3670–3070 cm〈sup〉–1〈/sup〉 in the experimental IR spectrum. The UV spectra are mainly formed from the ground state to the first, second, sixth and seventh excited state. The maximum absorption peak in the UV spectrum is below 200 nm and is formed by the transitions of π→π* and σ→π*. The absorption peaks at 268.8 nm and 221.4 nm are formed by the transitions of n→π* and π→π*. It can be seen from the electron-hole distribution diagram that these four excitations are all electron local excitation. This study may play a certain role in understanding the molecular structure and excitation properties of TBHQ, as well as the formation mechanism of its IR and UV spectra, and also conduce to understanding its antioxidant properties.
    Type of Medium: Online Resource
    ISSN: 1000-3290 , 1000-3290
    Language: Unknown
    Publisher: Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences
    Publication Date: 2021
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  • 5
    In: Acta Physica Sinica, Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences, Vol. 49, No. 6 ( 2000), p. 1180-
    Abstract: Blue-emitting porous silicon(PS) prepared by hydrothermal etching was treated by rapid thermal oxidation (RTO) process.Accompanying with the blue shift of the whole photoluminescence(PL) spectrum, the previous single PL peak split into two separate PL peaks. Simultaneously, the size-reduction and size-separation of the silicon nanocrystallites were observed. This result indicates that the short-wavelength emissions in PS are also strongly size-dependent.
    Type of Medium: Online Resource
    ISSN: 1000-3290 , 1000-3290
    Language: Unknown
    Publisher: Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences
    Publication Date: 2000
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  • 6
    In: Acta Physica Sinica, Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences, Vol. 68, No. 14 ( 2019), p. 148102-
    Abstract: Various kinds of super-resolution optical microscope techniques have been developed to break the diffraction barrier in the past decades. Confocal laser scanning microscopy is the super-resolution microscopy. It is widely used due to high resolution and depth selectivity in obtaining images. However, there are neither accurate nor rigorous measurement methods with a nanoscale resolution. In order to measure the resolution of vector beam confocal laser scanning microscopy accurately and rigorously, a nanoscale resolution standard sample is proposed and experimentally realized. This sample is composed of a series of accurate measure patterns and a couple of arrays of triangle finding structures. It allows a wide measurement range between 40 nm to 1000 nm, and provides appropriate measurement steps and high measurement accuracy. The measurement patterns can be efficiently figured out by using the found structures, and their structure line width can be easily calculated. The first standard sample is produced on a piece of amorphous silicon by electron beam lithography and inductive coupled plasma etching technology, and measured by the scanning electron microscopy. According to the test, the sample meets the requirements of accuracy for nanoscale resolution measurement. Optical testing is applied to the sample by a vector beam confocal laser scanning microscope. And the sample shows that the resolution is 96 nm (oil immersion, refractive index 1.52) under the irradiation of 405 nm radially polarized beams, which is far beyond the diffraction barrier. Furthermore, a metal structure standard sample, which is based on a piece of indium tin oxide glass, is produced to improve the signal contrast ratio of the silicon standard sample. The measurement patterns are fabricated by electron beam lithography and electron beam evaporation and made of 10 nm titanium and 100 nm gold. It works for both reflective and transmissive confocal laser scanning microscopy, and would obtain high resolution images with a better contrast ratio. These standard samples are able to test the performance of microscope system efficiently, and provide a more rigorous way to make sub-100 nm resolution measurement and a calibration guidance for point scanning super-resolution microscope. In the meantime, we find that nanoscale opticalimaging is affected not only by sample morphology, but also by the photoelectron property of the sample. Further study is required to understand the underlying mechanism.
    Type of Medium: Online Resource
    ISSN: 1000-3290 , 1000-3290
    Language: Unknown
    Publisher: Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences
    Publication Date: 2019
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  • 7
    In: Acta Physica Sinica, Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences, Vol. 64, No. 21 ( 2015), p. 210201-
    Abstract: Magnetic refrigeration is a cooling method based on the magnetocaloric effect, which uses solid magnetocaloric materials as refrigerant, and helium, water or other fluid as heat transfer fluids. Stirling refrigeration is a kind of mature gas regenerative cooling method, using helium gas as the refrigerant. These refrigerations have similar cycling characteristics, and are both safe, environmantal-friendly and high efficient cooling methods. Therefore, a hybrid magnetic refrigerator combined with Stirling gas refrigeration effect is proposed and designed. In our previous works for hybrid magnetic refrigeration, numerical simulation and experimental performance of the low-pressure hybrid magnetic refrigerator was carried out, and the cycling mechanism of hybrid magnetic refrigeration was also figured out. In this study, a numerical model for the high-pressure hybrid magnetic refrigeration cycle is established. The magnetic refrigeration materials are utilized as the regenerator matrix for both gas Stirling and active magnetic regenerative refrigeration in this model. Effects of gas Stirling and active magnetic regenerative refrigeration are combined to build a kind of high efficient refrigeration cycle. Ansys Fluent software is applied in this paper. Based on the physical model of hybrid refrigerator and the theories of magnetocaloric effect and numerical calculation of regenerator, computational fluid dynamics (CFD) model of high-pressure hybrid magnetic refrigerator is established. This paper describes the internal heat transfer mechanism of Stirling and magnetic refrigeration effect in an active regenerator. Some parameters of the model such as working frequency and utilization are analyzed and the best phase angle is figured out in order to couple these two cooling effects positively. Simulation results show that Stirling and magnetic cooling effects can be coupled positively at phase angle of 60o. Results also show that with increasing system pressure, which means to increase the utilization of the system, the system frequency can enhance the cooling performance of the system as well as improve the coefficient of performance (COP) of it. The results and analysis of the numerical model will be helpful for the construction of experimental prototype in our future work.
    Type of Medium: Online Resource
    ISSN: 1000-3290 , 1000-3290
    Language: Unknown
    Publisher: Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences
    Publication Date: 2015
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  • 8
    Online Resource
    Online Resource
    Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences ; 2007
    In:  Acta Physica Sinica Vol. 56, No. 8 ( 2007), p. 4943-
    In: Acta Physica Sinica, Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences, Vol. 56, No. 8 ( 2007), p. 4943-
    Abstract: The electrical characteristics of NiSi metal gate and their thermal stability were studied. A physical model is proposed to explain the increase in NiSi work function when the forming temperature is higher than 500 ℃. By measuring the sheet resistance of NiSi film prepared at different temperatures, it is shown that NiSi has the lowest resistance when formed at 400 ℃, which is stable from 400 to 600 ℃. The X-ray diffraction measurement for the NiSi samples formed at various temperatures revealed that NiSi phase was the main component at temperatures from 400 to 600 ℃. The capacitors formed by furnace annealing has higher equivalent oxide charge Qox and lower breakdown electric field Ebd, which proves that furnace annealing is unsuitable for NiSi metal gate fabrication due to the long time of thermal processing (400 ℃ for 30 min). The electrical characteristics of NiSi gate metal oxide semiconductor capacitors formed at various rapid thermal annealing(RTA) temperatures were studied. By comparing theC-V curves, Ig-Vg curves and Qox of the capacitors, it was found that when the RTA temperature is higher than 500 ℃, reaction between NiSi and gate oxide will occurr, reducing the quality of the gate dielectric. In conclusion, the suitable forming temperature of NiSi metal gate should be from 400 to 500 ℃. Moreover, the NiSi work function and Qox formed at 400, 450 and 500 ℃ respectively were also determined.
    Type of Medium: Online Resource
    ISSN: 1000-3290 , 1000-3290
    Language: Unknown
    Publisher: Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences
    Publication Date: 2007
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  • 9
    Online Resource
    Online Resource
    Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences ; 2019
    In:  Acta Physica Sinica Vol. 68, No. 23 ( 2019), p. 238101-
    In: Acta Physica Sinica, Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences, Vol. 68, No. 23 ( 2019), p. 238101-
    Type of Medium: Online Resource
    ISSN: 1000-3290
    Language: Unknown
    Publisher: Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences
    Publication Date: 2019
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  • 10
    Online Resource
    Online Resource
    Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences ; 2005
    In:  Acta Physica Sinica Vol. 54, No. 5 ( 2005), p. 2352-
    In: Acta Physica Sinica, Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences, Vol. 54, No. 5 ( 2005), p. 2352-
    Abstract: A novel silicon-based micron/nanometer structural composite system, silicon nanoporous pillar array(Si-NPA), was prepared on the substrate of single-crystal si licon (sc-Si) wafers by a hydrothermal etching method; and the studies on its mo rphological structural and optical properties were carried out. Structural exper iments disclose that Si-NPA could be well described by triple hierarchical struc tures: the array composed of micron-sized silicon pillars, the nanopores densely distributing on each pillar, and the silicon nanocrystallites constructing the walls of nanopores. Optical measurements prove that Si-NPA has good performances on light absorption and photoluminescence(PL). Based on the experimental data o f the integral reflectance spectrum, the structural and optical parameters such as complex refractive index, complex dielectric constant and absorption coeffici ent of Si-NPA are calculated by adopting Kramers-Kronig transformation; based on which, the origin of the notable difference between the optical properties of S i-NPA and sc-Si is discussed. Through analyzing the function relation between th e absorption coefficient of Si-NPA and the photon energy of incident light, the characteristic of the electronic structure of Si-NPA is proved to be that of a d irect-band-gap semiconductor, and the calculated bandgaps agree well with the PL peak energies given by experiments.
    Type of Medium: Online Resource
    ISSN: 1000-3290 , 1000-3290
    Language: Unknown
    Publisher: Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences
    Publication Date: 2005
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