Different diffraction lattice planes were used to investigate the quality profiles of molecular beam epitaxy epi-layer GaAs films on Si substrate by X-ray double crystal diffraction method.As the X-ray incident angle ...Different diffraction lattice planes were used to investigate the quality profiles of molecular beam epitaxy epi-layer GaAs films on Si substrate by X-ray double crystal diffraction method.As the X-ray incident angle increasing,the full width of half maximum(FWHM)also increases,that is,the quality getting worse in deeper layer.Therefore a clear figure of the degree of perfectness along the depth can be shown.The sample with strain surerlattice buffer layer has better quality than that without,especially in the surface lamella.展开更多
The photoluminescence(PL)spectra of C_(60) single crystals grown under double temperature gradient(DTG)and single temperature gradient(STG)techniques were investigated at room temperature.The results show that the PL ...The photoluminescence(PL)spectra of C_(60) single crystals grown under double temperature gradient(DTG)and single temperature gradient(STG)techniques were investigated at room temperature.The results show that the PL emission intensity increases first and then decreases with increasing illuminated power density for the C_(60) single crystals grown by both DTG and STG techniques.Furthermore,one main peak with a shoulder peak can be clearly distinguished at low illumination,while only one main peak without the shoulder peak can be seen at high illumination.The main peak undergoes a continuous blue shift and broadening with the increase of illuminated power density.The difference of PL emission energy at the same illumination density of DTG and STG samples may correlated with the degree of both the orientational disorder of C_(60) molecule and lattice perfectness.The Laue diffraction patterns show that the DTG sample has stronger strains and poorer crystalline quality than the STG sample.展开更多
C_(60) single crystals grown by a single-temperature-gradient technique were characterized by synchrotron radiation white beam x-ray topography and x-ray double crystal diffraction with Cu K_(α1) radiation on convent...C_(60) single crystals grown by a single-temperature-gradient technique were characterized by synchrotron radiation white beam x-ray topography and x-ray double crystal diffraction with Cu K_(α1) radiation on conventional x-ray source.The results show that the crystal is rather well crystallized.The x-ray topographies give an evidence of dendritic growth mechanism of C_(60) single crystal,and x-ray double crystal diffraction rocking curve shows that there are mosaic structural defects in the sample.A phase transition at 249±1.5K from a simple cubic to a face centered cubic structure is confirmed by in situ observation of synchrotron radiation white beam x-ray topography with the temperature varing from 230 to 295K.展开更多
This paper reviews the recent research progress in the hetero-nanostructure of silver nanoparticles on MOx (M=Mo, Ti and Si). It describes the general synthesis of hetero-nanostructure of silver nanoparticles on MOx, ...This paper reviews the recent research progress in the hetero-nanostructure of silver nanoparticles on MOx (M=Mo, Ti and Si). It describes the general synthesis of hetero-nanostructure of silver nanoparticles on MOx, and then outlines the interesting catalytic and sensing properties found in these hetero-nanostructures of silver nanoparticles on MOx.展开更多
In this paper we report on Longgudong,an Early Pleistocene cave site in south China which was systematically excavated in 1999 and 2000,and where human teeth and associated stone artifacts were discovered within the s...In this paper we report on Longgudong,an Early Pleistocene cave site in south China which was systematically excavated in 1999 and 2000,and where human teeth and associated stone artifacts were discovered within the same stratigraphic layer.The age of this site was estimated from faunal comparisons and palaeomagnetism and has been attributed to the Early Pleistocene,most probably the earlier Early Pleistocene.The human teeth from this site have been well studied.However,the stone artifacts are still unknown to most scholars.This paper thus presents an analysis of the lithics as the first firmly demonstrated stone tools associated with Early Pleistocene human fossils in south China.展开更多
文摘Different diffraction lattice planes were used to investigate the quality profiles of molecular beam epitaxy epi-layer GaAs films on Si substrate by X-ray double crystal diffraction method.As the X-ray incident angle increasing,the full width of half maximum(FWHM)also increases,that is,the quality getting worse in deeper layer.Therefore a clear figure of the degree of perfectness along the depth can be shown.The sample with strain surerlattice buffer layer has better quality than that without,especially in the surface lamella.
基金Supported by the National Natural Science Foundation of Chinathe Chinese National Committee of Science and Technology.
文摘The photoluminescence(PL)spectra of C_(60) single crystals grown under double temperature gradient(DTG)and single temperature gradient(STG)techniques were investigated at room temperature.The results show that the PL emission intensity increases first and then decreases with increasing illuminated power density for the C_(60) single crystals grown by both DTG and STG techniques.Furthermore,one main peak with a shoulder peak can be clearly distinguished at low illumination,while only one main peak without the shoulder peak can be seen at high illumination.The main peak undergoes a continuous blue shift and broadening with the increase of illuminated power density.The difference of PL emission energy at the same illumination density of DTG and STG samples may correlated with the degree of both the orientational disorder of C_(60) molecule and lattice perfectness.The Laue diffraction patterns show that the DTG sample has stronger strains and poorer crystalline quality than the STG sample.
基金Supported by BSRFBEPCthe Chinese National Committee of Science and Technology。
文摘C_(60) single crystals grown by a single-temperature-gradient technique were characterized by synchrotron radiation white beam x-ray topography and x-ray double crystal diffraction with Cu K_(α1) radiation on conventional x-ray source.The results show that the crystal is rather well crystallized.The x-ray topographies give an evidence of dendritic growth mechanism of C_(60) single crystal,and x-ray double crystal diffraction rocking curve shows that there are mosaic structural defects in the sample.A phase transition at 249±1.5K from a simple cubic to a face centered cubic structure is confirmed by in situ observation of synchrotron radiation white beam x-ray topography with the temperature varing from 230 to 295K.
基金supported by the National Natural Science Foundation of China (50972130, 20701033, 50772100 & 10874153)Qianjiang Talent Program of Zhejiang Province (QJD1002001)+1 种基金China Postdoctoral Science Foundation (201003048 & 20090450292)Open Project Program of State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, Jilin University
文摘This paper reviews the recent research progress in the hetero-nanostructure of silver nanoparticles on MOx (M=Mo, Ti and Si). It describes the general synthesis of hetero-nanostructure of silver nanoparticles on MOx, and then outlines the interesting catalytic and sensing properties found in these hetero-nanostructures of silver nanoparticles on MOx.
基金funded by the Chinese Academy of Sciences Pioneer Hundred Talents Programthe China-South Africa Bilateral Programme in Palaeolithic Archaeology to Gao Xing(Institute of Vertebrate Paleontology and Paleoanthropology, China-South Africa Joint Research Program-7)K.Kuman(National Research Foundation,Grant No.88480)
文摘In this paper we report on Longgudong,an Early Pleistocene cave site in south China which was systematically excavated in 1999 and 2000,and where human teeth and associated stone artifacts were discovered within the same stratigraphic layer.The age of this site was estimated from faunal comparisons and palaeomagnetism and has been attributed to the Early Pleistocene,most probably the earlier Early Pleistocene.The human teeth from this site have been well studied.However,the stone artifacts are still unknown to most scholars.This paper thus presents an analysis of the lithics as the first firmly demonstrated stone tools associated with Early Pleistocene human fossils in south China.
