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  • Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences  (26)
  • 1
    Online Resource
    Online Resource
    Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences ; 1989
    In:  Acta Physica Sinica Vol. 38, No. 4 ( 1989), p. 689-
    In: Acta Physica Sinica, Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences, Vol. 38, No. 4 ( 1989), p. 689-
    Abstract: The XPS, oxygen content and resistance-temperature relationship of YBa2Cu3-xAlxO7-y single phase system are determined. The experimental results show that Al can possibly substitute the Cu and Y positions in 1-2-3-phase partially. Because of the existence of Al3+, the content of oxygen increases, the environment of oxygen tends to be uniform, the difference of the two states of O15 in XPS is indistinct. The presence of Cu3+ is clearly observed.
    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: 1989
    detail.hit.zdb_id: 203490-6
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  • 2
    In: Acta Physica Sinica, Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences, Vol. 63, No. 15 ( 2014), p. 157101-
    Abstract: Crystal structure, electronic properties, and stability of anatase and rutile Nb-doped TiO2 (Nb:TiO2) compounds with different doping concentrations are studied by the combination of GGA and GGA+U methods within the density functional theory based first-principle calculation. And the main research work and contents are listed as follows: The anatase Nb:TiO2 appears as a degenerated semiconductor which behaves as an intrinsic metal. Its metallic property arises from Nb substitution into the Ti site, providing electrons to the conduction band. In contrast, the rutile Nb:TiO2 shows insulating behaviors. Ionization efficiency of Nb in anatase Nb:TiO2 is higher than that in rutile. We expect that anatase Nb:TiO2 is a potential material for transparent conducting oxide (TCO) while rutile Nb:TiO2 is not. The doped systems show different electronic characteristics, such as band structure, Fermi energy, and effective mass of carriers at different doping levels. In higher dopant concentration nNb, the ionization efficiency decreases slightly. Calculated defect-formation energy shows that Ti-rich material growth conditions are not in favor of the introduction of Nb while Nb can be easily doped in Nb:TiO2 under O-rich growth conditions. Nb dopant is difficult to be doped at higher doping level for both anatase and rutile Nb:TiO2.
    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
    In: Acta Physica Sinica, Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences, Vol. 38, No. 1 ( 1989), p. 60-
    Abstract: The measurements of X-ray diffraction, d.c. resistance versus temperature and Hall coefficients at low temperature have been performed for YBa2Cu3-xMxOy systems. (x = 0.00, 0.025,0.05,0.075,0.10,0.125,0.15,0.20,0.25,0.275,0.30,0.325,0.35,0.375,0.40 for M = Co; x=0.025,0.05,0.075,0.10,0.15,0.20,0.30 for M = Zn)The crystallographic data show that an orthorhombic-tetragonal phase transition takes place as Co content increases,while the crystal structure exhibit drastic changes with Zn content. The measurement of resistances indicates that a metal-semiconductor transition occurs at certain x for Co dopant hut not found for Zn dopant. The hole carrier concentration raduces with Co content monotoneous-iy but varies nonmonotoneously with Zn content, giving a maximum at about x= 0.15 The concepts of localization and acceptor are used to explain these phenomena. The suppression of Tc for both systems is discussed with various possible suppression mechanisms.
    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: 1989
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  • 4
    Online Resource
    Online Resource
    Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences ; 2020
    In:  Acta Physica Sinica Vol. 69, No. 17 ( 2020), p. 172901-
    In: Acta Physica Sinica, Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences, Vol. 69, No. 17 ( 2020), p. 172901-
    Abstract: The back-streaming neutron beam line (Back-n) was built in the beginning of 2018, which is part of the China Spallation Neutron Source (CSNS). The Back-n is the first white neutron beam line in China, and its main application is for nuclear data measurement. For most of neutron-induced nuclear reaction measurements based on white neutron facilities, the beam of gamma rays accompanied with neutron beam is one of the most important experimental backgrounds. The back streaming neutron beam is transported directly from the spallation target to the experimental station without any moderator or shielding, the flux of the in-beam gamma rays in the experimental station is much larger than those of these facilities with neutron moderator and shielding. Therefore, it is necessary to consider the influence of in-beam gamma rays on the experimental results. Studies of the in-beam gamma rays are carried out at the back-n. Monte-Carlo simulation is employed to obtain the energy distribution and the time structure of the in-beam gamma rays. According to the simulation results, when the neutron flight time is longer than 1.0 μs the energy distribution of the in-beam gamma rays does not vary with flight time. Therefore, the time structure of these gamma rays can be measured without the correction of the detection efficiency. In this work, the time structure of the in-beam gamma rays in the low neutron energy region is measured by both direct and indirect methods. In the direct measurement, a 〈sup〉6〈/sup〉Li loaded ZnS(Ag) scintillator is located on the neutron beam line and the time of flight method is used to determine the time structure of neutrons and gamma rays. The gamma rays are separated from neutrons with pulse-shape discrimination. The black filter method is used to verify the particle discrimination results. In the indirect measurement, the C〈sub〉6〈/sub〉D〈sub〉6〈/sub〉 scintillation detectors are used to measure the gamma rays scattered off a Pb sample on the way of the neutron beam. The time structure of the in-beam gamma rays is derived from that of the scattered gamma rays. The experimental results are in good agreement with the simulations with the time-of-flight between 12 μs and 2.0 ms. Besides, according to the simulation results, the intensity of the in-beam gamma rays is 1.21 × 10〈sup〉6〈/sup〉 s〈sup〉–1〈/sup〉·cm〈sup〉–2〈/sup〉 in the center of the experimental station 2 of Back-n, which is 76.5 m away from the spallation target of CSNS.
    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: 2020
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  • 5
    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. 22 ( 2021), p. 222801-
    In: Acta Physica Sinica, Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences, Vol. 70, No. 22 ( 2021), p. 222801-
    Abstract: The data of neutron capture cross section are very important for the research of nuclear astrophysics, advanced nuclear energy development. Owing to the limitation of neutron source and detector, the experimental data of neutron capture cross section in an energy range of 1 eV–10 keV were almost blank in China. The first Chinese gamma-ray total absorption facility has been constructed in the key laboratory of nuclear data at China institute of atomic energy, which consists of 40 BaF〈sub〉2〈/sub〉 detector units. The BaF〈sub〉2〈/sub〉 crystal shell with a thickness of 15 cm and an inner radius of 10 cm covers 95.2% of the solid angle. On-line measurement method of neutron capture reaction cross section is established on the back-streaming white neutron source of China spallation neutron source by using the upgraded facility. The cross section of 〈sup〉197〈/sup〉Au neutron capture reaction is measured for the first time under the experimental condition of irregular 30 mm neutron beam spot. The measured position of resonance peak is well consistent with the relevant data of ENDF evaluation database, which verifies the reliability of the measurement device and measurement technology, and thus laying the foundation for the acquisition of high precision cross section in future.
    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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  • 6
    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. 8 ( 2021), p. 082901-
    In: Acta Physica Sinica, Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences, Vol. 70, No. 8 ( 2021), p. 082901-
    Abstract: At present, there exist few proton-beam terminals for the detector calibration in the world. Meanwhile, most of these terminals provide monoenergetic protons. Back-n white neutron source from China Spallation Neutron Source(CSNS) was put into operation in 2018. Based on the white neutron flux ranging from 0.5 eV to 200 MeV from the CSNS Back-n white neutron source, continuous-energy protons involved in a wide energy spectrum can be acquired from the 〈sup〉1〈/sup〉H(n, el) reaction. Adopting this method, a new research platform for researches such as proton calibration is realized at CSNS. As hydrogen exists as gas at normal temperature and pressure, in the selecting of the proton-converting target, the hydrogen-rich compounds are preferential considered. Considering the reaction cross sections of the 〈sup〉1〈/sup〉H(n, el), 〈sup〉12〈/sup〉C(n, p)〈sup〉12〈/sup〉B, 〈sup〉12〈/sup〉C(n, d)〈sup〉11〈/sup〉B, 〈sup〉12〈/sup〉C(n, t)〈sup〉10〈/sup〉B, 〈sup〉12〈/sup〉C(n, 〈sup〉3〈/sup〉He)〈sup〉10〈/sup〉Be, 〈sup〉12〈/sup〉C(n, α)〈sup〉9〈/sup〉Be and 〈sup〉1〈/sup〉H(n, γ)〈sup〉2〈/sup〉H, polyethylene and polypropylene are suitable for serving as targets in this research. Based on a 3U PXIe, digitizers with 1 GSps sampling rate and 12 bit resolution are utilized to digitize and record the output signals of telescopes. The time and amplitude information of each signal are extracted from its recorded waveform. Proton fluxes can be calculated by using the neutron energy spectrum and the cross section of the 〈sup〉1〈/sup〉H(n, el) reaction. Using the γ-flash event as the starting time of the time-of-flight (TOF) and the time information of signal in detector as the stopping time, the kinematic energy of each secondary proton can be deduced from the TOF and the angle of the detector. A calibration experiment on three charged particle telescopes, with each telescope consisting of a silicon detector and a CsI(Tl) detector, is carried out on this research platform. The readout methods of the CsI(Tl) detectors in these three telescopes are different. In the calibration experiment, Δ〈i〉E-〈/i〉〈i〉E〈/i〉 two-dimensional spectra and amplitude-〈i〉E〈/i〉〈sub〉p〈/sub〉 two-dimensional spectra of these telescopes are obtained. Through comparing these particle identification spectra, the SiPM is chosen as the signal readout method for CsI(Tl) detectors in the charged particle telescopes. These researches provide experimental evidence for the construction of the charged particle telescope at Back-n, and also illustrate the feasibility of wide-energy spectrum proton calibration based on the Back-n white neutron source.
    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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  • 7
    Online Resource
    Online Resource
    Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences ; 2024
    In:  Acta Physica Sinica Vol. 73, No. 7 ( 2024), p. 072801-
    In: Acta Physica Sinica, Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences, Vol. 73, No. 7 ( 2024), p. 072801-
    Abstract: Neutron capture reaction is one of the neutron reactions and plays an important role in using reactor control rods and shell materials, designing nuclear device structures, and studying nuclear astrophysics S processes and element origins. The 4π BaF〈sub〉2〈/sub〉 detection device has advantages such as high time resolution, low neutron sensitivity, and high detection efficiency, thus making it suitable for measuring neutron radiation capture reaction cross-section data. In order to fill the gap in our neutron capture reaction data in the keV energy range and improve their accuracy, the Key Laboratory of Nuclear Data at the Chinese Institute of Atomic Energy (CIAE) has established a Gamma Total Absorption Facility (GTAF), which consists of 28 hexagonal BaF〈sub〉2〈/sub〉 crystals and 12 pentagonal BaF〈sub〉2〈/sub〉 crystals to form a spherical shell with an external diameter of 25 cm and an internal diameter of 10 cm, covering 95.2% of the solid angles. The Back-n beam line of the Chinese Spallation Neutron Source (CSNS) is a back-streaming white beam line that covers neutron energy ranging from a few eV to several hundred MeV, making it suitable for measuring neutron capture cross-sections. The reaction cross-section data of 〈sup〉197〈/sup〉Au is measured by using GTAF on the Back-n beam line. The measurement data are preliminarily background deducted through energy screening, PSD method, and crystal multiplicity screening. Subsequently, the background is analyzed and deducted based on the measurement data of 〈sup〉nat〈/sup〉C and empty samples, and the yield of 〈sup〉197〈/sup〉Au capture reaction is obtained. Resonance parameters are a set of parameters extracted from experimental data to describe the resonance curve, which can eliminate the influence of experimental conditions on resonance data and are more important than the cross-section obtained from experiments. The resonance energy, neutron resonance width, and gamma resonance width parameters of 〈sup〉197〈/sup〉Au at 1–100 eV are fitted by using the SAMMY program. From the comparison between the resonance curves obtained from experimental measurements and the resonance parameters obtained from fitting with the ENDF/B-VIII.0 database, it can follow that the experimental measurement results are in good agreement with the database, nevertheless, there exist some differences in the resonance parameter, which may be due to the GTAF energy resolution, Back-n neutron spectrum measurement accuracy, and the experimental background deduction method. Our next work is to identify the sources of difference.
    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: 2024
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  • 8
    Online Resource
    Online Resource
    Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences ; 2023
    In:  Acta Physica Sinica Vol. 72, No. 21 ( 2023), p. 218102-
    In: Acta Physica Sinica, Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences, Vol. 72, No. 21 ( 2023), p. 218102-
    Abstract: Transition-metal phosphorous chalcogenide 〈i〉M〈/i〉PS (〈i〉M〈/i〉 = transition metal), an emerging type of two-dimensional (2D) van der Waals material with the unique optical and opto-electronic properties, has received much attention. The quasi-one-dimensional chain structure of Nb〈sub〉4〈/sub〉P〈sub〉2〈/sub〉S〈sub〉21〈/sub〉 will possess the strong anisotropic optical and photoelectric properties. Therefore, the single crystal and low-dimensional materials of Nb〈sub〉4〈/sub〉P〈sub〉2〈/sub〉S〈sub〉21〈/sub〉 have potential applications in new polarization controllers, polarization-sensitive photoelectronic detectors, etc. However, there is still a lack of research on the anisotropic optical properties of the high-quality Nb〈sub〉4〈/sub〉P〈sub〉2〈/sub〉S〈sub〉21〈/sub〉 single crystals. Herein, the millimeter-sized Nb〈sub〉4〈/sub〉P〈sub〉2〈/sub〉S〈sub〉21〈/sub〉 single crystals are successfully prepared by the chemical vapor transport method. The chemical composition, the crystal structure and the anisotropic optical properties of the Nb〈sub〉4〈/sub〉P〈sub〉2〈/sub〉S〈sub〉21〈/sub〉 single crystals are carefully analyzed. The energy dispersive X-ray spectroscopy results show that the element distribution is uniform and the element ratio is close to the stoichiometric ratio. The X-ray diffraction and the transmission electron microscopy results show a good crystallinity. The absorption spectra shows that the optical band gap of the Nb〈sub〉4〈/sub〉P〈sub〉2〈/sub〉S〈sub〉21〈/sub〉 single crystal is 1.8 eV. Interestingly, the Nb〈sub〉4〈/sub〉P〈sub〉2〈/sub〉S〈sub〉21〈/sub〉 single crystal can be mechanically exfoliated to obtain few-layer material. The thickness-dependent Raman spectra show that the Raman vibration peaks of bulk and few-layer Nb〈sub〉4〈/sub〉P〈sub〉2〈/sub〉S〈sub〉21〈/sub〉 each have only a weak shift, indicating a weak interlayer interaction in the Nb〈sub〉4〈/sub〉P〈sub〉2〈/sub〉S〈sub〉21〈/sub〉 single crystal. In order to make an in-depth study of the optical properties of Nb〈sub〉4〈/sub〉P〈sub〉2〈/sub〉S〈sub〉21〈/sub〉 single crystals, the polarized-dependent Raman spectra and the femtosecond transient absorption (TA) spectra by using pump pulses and probe pulses with a wavelength of 400 nm and a wavelength range of 500–700 nm are recorded. Importantly, the polarized-dependent Raman scattering spectra with the angle-dependent measurements reveal that the intensity of Raman peak at 202 cm〈sup〉–1〈/sup〉 and at 489 cm〈sup〉–1〈/sup〉 show a 2-fold symmetry and a 4-fold symmetry in the parallel and vertical polarization configurations, respectively. Moreover, the results of ultrafast carrier dynamics with the in-plane rotation angles of Nb〈sub〉4〈/sub〉P〈sub〉2〈/sub〉S〈sub〉21〈/sub〉 single crystals in the parallel polarization configurations, clearly indicate that both the hot carrier number and the relaxation rate after photoexcitation have the in-plane anisotropic properties. These results are useful in understanding the in-plane anisotropic optical properties of Nb〈sub〉4〈/sub〉P〈sub〉2〈/sub〉S〈sub〉21〈/sub〉 single crystal, which can further promote their applications in the low-dimensional angle-dependent optoelectronics.
    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: 2023
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  • 9
    In: Acta Physica Sinica, Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences, Vol. 58, No. 2 ( 2009), p. 1321-
    Abstract: Transient fluorescence dynamics of a new kind of porphyrin side-chain polymer film [poly[porphyrin acrylate-styrene] (P[(por)A-S]) at high excitation density has been measured by using time-resolved fluorescence spectroscopy. The fluorescence decay becomes more rapid with the increase of the interchain polymer concentration. The origin of the concentration quenching has been analysed according to the Frster-type bimolecular annihilation theory. The theoretical analyses are in good agreement with the experimental results. Rosults show that, in the case of high excitation density, the Frster-type bimolecular annihilation is the main reason of the fast initial luminescence decay and the low luminescence efficiency of the porphyrin side-chain polymers.
    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: 2009
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  • 10
    In: Acta Physica Sinica, Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences, Vol. 61, No. 23 ( 2012), p. 234204-
    Abstract: The thermometry based on absorption spectroscopy and developing of a temperature sensor is introduced, in which temperature is retrieved by measuring line strength ratio between a pair of absorptions of water vapor near 1.4 μm. The temperature sensor is first calibrated on a tubular furnace and then used to verify measurement results with the heating tube whose both sides are open, an average fluctuation of about 50 K is obtained at each temperature setpoint. Some new absorption lines of H2O near one absorption (centered at 7153.7 cm -1) of the selected line pair are observed during demonstration measurements for CH4/air flat flame burner. These absorption lines overlapping with 7153.7 cm-1, are not listed in HITRAN08 database while HITEMP data give absorption information about these wave number positions. But line center of the other absorption (centered at 7154.354 cm-1) in HITEMP seems different from our measurement and HITRAN database. A combination of our calibrated results from tubular furnace and line parameters of new features from HITEMP is chosen and some results measured at different equivalence ratios on the burner are shown here.
    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: 2012
    detail.hit.zdb_id: 203490-6
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