The luminescent properties of Gd_(3)PO_(7):Eu were investigated in UV and VUV regions.This phosphor has so strong emissions around 618.5 nm under UV excitation,especially around 209\,nm,so that it has a better colour ...The luminescent properties of Gd_(3)PO_(7):Eu were investigated in UV and VUV regions.This phosphor has so strong emissions around 618.5 nm under UV excitation,especially around 209\,nm,so that it has a better colour saturation than that of Y_(2)O_(3):Eu.It would be a new potential red phosphor for lamp and other applications with UV-excitation source or even for displaying device.In the VUV excitation spectrum of Eu^(3+)emissions,energy absorptions by Gd^(3+),Gd-O and PO_(4)^(3-) were observed,on which it can be inferred that there are three kinds of energy transferring processes to Eu^(3+)ions.The energy absorptions of Gd^(3+),Gd-O and PO_(4)^(3-) are induced by 4f→4f transitions,band-gap transition of Gd_(3)PO_(7) and intramolecular(2t_(2)→2a,3t_(2))transition,respectively.The energy transfer efficiency of the PO_(4)^(3-) intramolecular transition is lower compared with that of the band-gap transition(Gd-O).展开更多
The Transantarctic Mountains are an important corridor between the East Antarctic Ice Sheet and the Western Ross Sea,where most current ice streams and outlet glaciers arise.We investigated Ricker Hills,the largest ex...The Transantarctic Mountains are an important corridor between the East Antarctic Ice Sheet and the Western Ross Sea,where most current ice streams and outlet glaciers arise.We investigated Ricker Hills,the largest exposed mountainous region between Southern Victoria Land and Terra Nova Bay,and dated the glacial landforms using in-situ cosmogenic-nuclide 10 Be surface exposure dating to reconstruct the paleo-glacial dynamics.The surface of the Hollingsworth glacier lowered since the middle of Marine Isotope Stage(MIS)2(22.1 ka);therefore,the Last Glacial Maximum(LGM)occurred before that period.Cosmogenic,geomorphic,and climatic records constrained the glacial surface slope to be between 5.4°and 6.8°.The ice was 270-320 m thicker at the LGM(MIS 2)than presently but did not override the top surface of the Benson Knob.Moreover,previous glacial periods such as the local LGM(MIS 4)or Penultimate Glacial Maximum(MIS 6)maintained thicker ice than the LGM(MIS 2).The Ross Ice Shelf opening during the mid-Holocene(~6 ka)caused the rapid collapse of the terminal outlet glaciers and supplied notable snow accumulation upstream,which stagnated lowering.The greatest lowering and retreat occurred during the late Holocene(2.3~0.8 ka),when elephant seal colonies thrived in the Ross Embayment.展开更多
基金Supported by the National Natural Science Foundation of China under Grant No.20071031.
文摘The luminescent properties of Gd_(3)PO_(7):Eu were investigated in UV and VUV regions.This phosphor has so strong emissions around 618.5 nm under UV excitation,especially around 209\,nm,so that it has a better colour saturation than that of Y_(2)O_(3):Eu.It would be a new potential red phosphor for lamp and other applications with UV-excitation source or even for displaying device.In the VUV excitation spectrum of Eu^(3+)emissions,energy absorptions by Gd^(3+),Gd-O and PO_(4)^(3-) were observed,on which it can be inferred that there are three kinds of energy transferring processes to Eu^(3+)ions.The energy absorptions of Gd^(3+),Gd-O and PO_(4)^(3-) are induced by 4f→4f transitions,band-gap transition of Gd_(3)PO_(7) and intramolecular(2t_(2)→2a,3t_(2))transition,respectively.The energy transfer efficiency of the PO_(4)^(3-) intramolecular transition is lower compared with that of the band-gap transition(Gd-O).
基金supported by Korea Polar Research Institute(PE22090)。
文摘The Transantarctic Mountains are an important corridor between the East Antarctic Ice Sheet and the Western Ross Sea,where most current ice streams and outlet glaciers arise.We investigated Ricker Hills,the largest exposed mountainous region between Southern Victoria Land and Terra Nova Bay,and dated the glacial landforms using in-situ cosmogenic-nuclide 10 Be surface exposure dating to reconstruct the paleo-glacial dynamics.The surface of the Hollingsworth glacier lowered since the middle of Marine Isotope Stage(MIS)2(22.1 ka);therefore,the Last Glacial Maximum(LGM)occurred before that period.Cosmogenic,geomorphic,and climatic records constrained the glacial surface slope to be between 5.4°and 6.8°.The ice was 270-320 m thicker at the LGM(MIS 2)than presently but did not override the top surface of the Benson Knob.Moreover,previous glacial periods such as the local LGM(MIS 4)or Penultimate Glacial Maximum(MIS 6)maintained thicker ice than the LGM(MIS 2).The Ross Ice Shelf opening during the mid-Holocene(~6 ka)caused the rapid collapse of the terminal outlet glaciers and supplied notable snow accumulation upstream,which stagnated lowering.The greatest lowering and retreat occurred during the late Holocene(2.3~0.8 ka),when elephant seal colonies thrived in the Ross Embayment.
