By using surface effects(Auger electron spectroscopy,X-ray photoelectron spectroscopy,polar Kerr effect)and volume effects(magnetization,torque curve)the physical process of surface oxidation of rare earth-transition ...By using surface effects(Auger electron spectroscopy,X-ray photoelectron spectroscopy,polar Kerr effect)and volume effects(magnetization,torque curve)the physical process of surface oxidation of rare earth-transition metal amorphous magneto-optical thin films was studied in this paper.The rare earth elements oxidize preferentially and rich at the film surface,and the transition metals deplete in oxidation layer.Fe_2O_3 in the surface oxidation layer contributes to the planar magnetization,and thereby the anomalous peak appears near 180° on the torque curves and the amplitude of the peaks is related to the depth of surface oxidation layers.The iron bonds to oxygen easier than the cobolt.RE-Co magneto-optieal thin films have good properties of resistance to oxidation and humidity.展开更多
The total number of atmospheric particle (AP) is an important datum for planetary science and geoscience. Estimating entire AP number is also a familiar question in general physics. With standard atmosphere model, con...The total number of atmospheric particle (AP) is an important datum for planetary science and geoscience. Estimating entire AP number is also a familiar question in general physics. With standard atmosphere model, considering the number difference of AP caused by rough and uneven in the earth surface below, the sum of dry clean atmosphere particle is . So the whole number of AP including water vapor is . The rough estimation for the total number of AP on other planets (or satellites) in condensed state is also discussed on the base of it.展开更多
Selective hydrogenation of unsaturated aldehydes remains a grand challenge in controlling chemoselectivity up to now.We synthesized a series of PtFex/CeO_(2)catalysts,which were characterized by X-ray diffraction(XRD)...Selective hydrogenation of unsaturated aldehydes remains a grand challenge in controlling chemoselectivity up to now.We synthesized a series of PtFex/CeO_(2)catalysts,which were characterized by X-ray diffraction(XRD),transmission electron microscopy(TEM),X-ray photoelectron spectroscopy(XPS)as well as temperature-programmed-reduction by hydrogen(H2-TPR).The catalytic performance of PtFex/CeO_(2),including cinnamaldehyde(CAL)conversion and selectivity toward cinnamyl alcohol(COL),is improved remarkably by introduction of Fe species in the Pt particles in the selective CAL hydrogenation under mild conditions.XPS results indicate that the electron transfer from Fe to Pt promotes CAL adsorption,resulting in the enhanced CAL conversion.And the COL selectivity is improved by CAL adsorption via an interaction of C=O group with surface oxygen defect sites because of interaction between PtFe and CeO_(2)support.In all,this study may provide some hints to design efficient nano Pt particles for the selective hydrogenation.展开更多
文摘By using surface effects(Auger electron spectroscopy,X-ray photoelectron spectroscopy,polar Kerr effect)and volume effects(magnetization,torque curve)the physical process of surface oxidation of rare earth-transition metal amorphous magneto-optical thin films was studied in this paper.The rare earth elements oxidize preferentially and rich at the film surface,and the transition metals deplete in oxidation layer.Fe_2O_3 in the surface oxidation layer contributes to the planar magnetization,and thereby the anomalous peak appears near 180° on the torque curves and the amplitude of the peaks is related to the depth of surface oxidation layers.The iron bonds to oxygen easier than the cobolt.RE-Co magneto-optieal thin films have good properties of resistance to oxidation and humidity.
文摘The total number of atmospheric particle (AP) is an important datum for planetary science and geoscience. Estimating entire AP number is also a familiar question in general physics. With standard atmosphere model, considering the number difference of AP caused by rough and uneven in the earth surface below, the sum of dry clean atmosphere particle is . So the whole number of AP including water vapor is . The rough estimation for the total number of AP on other planets (or satellites) in condensed state is also discussed on the base of it.
基金This work was supported by the National Baltic Research Program of China （Grant No.2003CB415100） and Key Project of Yunnan Natural Science Foundation （Grant No.2003C0002Z）.
基金Project supported by the Natural Science Foundation of Inner Mongolia Autonomous Region(2020BS02016)the Program of Higher-level Talents of Inner Mongolia Agricultural University(NDYB2018-23)the Program of Scientific Research of Inner Mongolia Autonomous Region(NJZY19046)。
文摘Selective hydrogenation of unsaturated aldehydes remains a grand challenge in controlling chemoselectivity up to now.We synthesized a series of PtFex/CeO_(2)catalysts,which were characterized by X-ray diffraction(XRD),transmission electron microscopy(TEM),X-ray photoelectron spectroscopy(XPS)as well as temperature-programmed-reduction by hydrogen(H2-TPR).The catalytic performance of PtFex/CeO_(2),including cinnamaldehyde(CAL)conversion and selectivity toward cinnamyl alcohol(COL),is improved remarkably by introduction of Fe species in the Pt particles in the selective CAL hydrogenation under mild conditions.XPS results indicate that the electron transfer from Fe to Pt promotes CAL adsorption,resulting in the enhanced CAL conversion.And the COL selectivity is improved by CAL adsorption via an interaction of C=O group with surface oxygen defect sites because of interaction between PtFe and CeO_(2)support.In all,this study may provide some hints to design efficient nano Pt particles for the selective hydrogenation.
